Gas turbine operation

Abstract

The invention describes a gas turbine engine (10) for an aircraft. The gas turbine engine comprises: a combustor device (16), including a combustion chamber (120) and a plurality of fuel spray nozzles (124) designed to inject fuel into the combustion chamber (120), wherein the plurality of fuel spray nozzles (124) comprises a first subset (124A) of fuel spray nozzles (124) and a second subset (124B) of fuel spray nozzles (124), wherein the combustor device (16) can operate under a condition in which each of the fuel spray nozzles of the first subset (124A) of fuel spray nozzles (124) is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset (124B) of fuel spray nozzles (124), wherein a ratio of the number of nozzlesThe ratio of fuel spray nozzles (124) in the first subset (124A) of fuel spray nozzles (124) to the number of fuel spray nozzles (124) in the second subset (124B) of fuel spray nozzles (124) is in the range of 1:3 to 1:6. A thrust nvPM emission index ratio is defined as: where: EIralid is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine (10) if it is operating at approximately 7% of the available thrust under given operating conditions; EImaxTO is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine (10) if it is operating at approximately 100% of the available thrust under given operating conditions; is the thrust of the gas turbine engine (10) at approximately 100% of the available thrust in kN under the given operating conditions; and is the thrust of the gas turbine engine (10) at approximately 7% of theAvailable thrust in kN under given operating conditions. The thrust emission index ratio (nvPM) is greater than 0.02. The gas turbine engine (10) is designed to supply fuel comprising sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles (124). Operating methods for the gas turbine engine are also described. Figure for abstract: Figure 3

Description

Title of the invention: Operation of a gas turbine

[0001] SCOPE OF APPLICATION

[0002] This description relates to non-volatile particulate matter (nvPM) emissions from gas turbine engines, specifically aircraft gas turbine engines. This description provides various methods of operating a gas turbine engine and gas turbine engines. More specifically, this application relates to methods of operating gas turbine engines using a fuel that includes a sustainable aviation fuel (SAF) and gas turbine engines designed to operate using a fuel that includes an SAF.

[0003] CONTEXT

[0004] There is an expectation in the aeronautical industry regarding a trend towards the use of fuels other than the traditional kerosene-based jet fuels generally used at present.

[0005] The inventors have observed that the emissions of a gas turbine engine are sensitive to the fuel used; in particular, the amount of nvPM produced by the engine varies depending on the operating parameters and the type of fuel used. Therefore, there is a need to take into account the fuel properties of these different fuels and to adjust the operating processes of gas turbine engines accordingly.

[0006] SUMMARY

[0007] According to a first aspect, a gas turbine engine for an aircraft is provided, comprising any of the following characteristics:

[0008] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles in the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles in the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0009] in which:

[0010] A first nvPM emission index ratio at idle-PMD is defined as:

[0011] [Math.l] ^slow motion FI 1 nias TO

[0012] where:

[0013] Δ / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[0014] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the given operating conditions:

[0015] the first NVPM-PMD emission index ratio of the gas turbine engine at idle is less than 3; and

[0016] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0017] Advantageously, reducing nvPM in the exhaust of a gas turbine engine contributes to a reduction in undesirable engine emissions. For example, depending on operating conditions, reducing nvPM in this way can lead to a reduced degree of soot deposits within the engine, within and / or downstream of the combustor, and / or an improvement in local air quality. Furthermore, at certain stages of an aircraft's flight (where contrail formation is otherwise expected), reducing nvPM in the exhaust can lead to a reduction in contrail strength and / or the time required for them to disperse. Moreover, it has been recognized that certain parts of the flight cycle during which nvPM is reduced (or most reduced) can be targeted to achieve a desired outcome, for example, in terms of environmental impact.Strictly by way of example, a lower nvPM under cruise conditions can significantly reduce the impact of radiative forcing from contrails. Strictly by way of further example, a lower nvPM under idle conditions can significantly improve local ground air quality in the engine operating region. Strictly by way of further example, a lower nvPM under PMD conditions can significantly reduce the peak nvPM production rate during the flight cycle and / or improve ground air quality and / or air quality in the engine operating region. These considerations can be applied to all aspects of the description.

[0018] A number of parameters related to the operation of a gas turbine engine have been determined to influence, or to be an important factor in, the configuration and arrangement of the engine's combustor device when certain types of fuel, such as sustainable aviation fuel, are burned. Accordingly, any of the following parameters can be advantageously taken into account when determining, for example, the operational settings, combustor device arrangement, and / or combustor device configuration, in order to influence and / or optimize how the fuel is dispensed, ignited, and / or burned within the gas turbine engine. These considerations can be applied to all aspects of the description.

[0019] The first NvPM-PMD emission index ratio of the gas turbine engine at idle may be greater than zero.

[0020] The first nvPM-PMD emission index ratio at idle may be less than 2.54 and preferably may be less than 2.33 and more preferably may be less than 2.12.

[0021] The first nvPM-PMD emission index ratio at idle may be less than or equal to 1.5 and preferably may be less than or equal to 1 and more preferably may be less than or equal to 0.5.

[0022] The first nvPM-PMD emission index ratio may be less than or equal to 0.377 and preferably may be less than or equal to 0.346 and more preferably may be less than or equal to 0.314.

[0023] The first nvPM-PMD emission index ratio at idle may be less than or equal to 0.319 and preferably may be less than or equal to 0.293 and more preferably may be less than or equal to 0.266.

[0024] The first nvPM-PMD emission index ratio can be greater than or equal to 0.184 and preferably can be greater than or equal to 0.207 and more preferably can be greater than or equal to 0.23.

[0025] The first nvPM-PMD emission index ratio can be greater than or equal to 0.212 and preferably can be greater than or equal to 0.239 and more preferably can be greater than or equal to 0.265.

[0026] The first nvPM idle-PMD emission index ratio can be in the range of 0.184 to 0.377 and preferably can be in the range of 0.207 to 0.346 and more preferably can be in the range of 0.230 to 0.314.

[0027] The first nvPM idle-PMD emission index ratio can be in the range of 0.212 to 0.319 and preferably can be in the range of 0.239 to 0.293 and more preferably can be in the range of 0.265 to 0.266.

[0028] The first NVPM emission index ratio at idle-PMD may be less than 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.377, or in any range defined between any two of these values.

[0029] A second nvPM emission index ratio at idle-PMD can be defined as:

[0030] [Math.2] The slowed-down SAF / p I. / 1 maxTu, S AF

[0031] where:

[0032] Ê / raienti ,saf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 7% of the available thrust for the given operating conditions, or for different given operating conditions, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0033] £'7maxTo,sAF is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 100% of available thrust for the same given operating conditions at which EIialeaü jSaf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0034] Ê / raienti jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for the same given operating conditions to which EIalenü ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[0035] Æ'ZmaxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the same given operating conditions under which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel; and

[0036] the second nvPM-PMD emission index ratio of the gas turbine engine may be less than 1.

[0037] The second NvPM-PMD emission index ratio of the gas turbine engine at idle may be greater than zero.

[0038] The second nvPM-PMD emission index ratio at idle may be less than or equal to 0.8 and preferably may be less than or equal to 0.6 and more preferably may be less than or equal to 0.4.

[0039] The second nvPM-PMD emission index ratio may be less than or equal to 0.178 and preferably may be less than or equal to 0.164 and more preferably may be less than or equal to 0.149.

[0040] The second nvPM-PMD emission index ratio can be greater than or equal to 0.03 and preferably can be greater than or equal to 0.06 and more preferably can be greater than or equal to 0.09.

[0041] The second nvPM-PMD emission index ratio can be greater than or equal to 0.118 and preferably can be greater than or equal to 0.133 and more preferably can be greater than or equal to 0.148.

[0042] The second nvPM idle-PMD emission index ratio can be in the range of 0.118 to 0.178 and preferably can be in the range of 0.133 to 0.164 and more preferably can be in the range of 0.148 to 0.149.

[0043] The second NvPM-PMD emission index ratio may be less than 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1, or in any range defined between any two of these values.

[0044] The second emission index ratio of nvPM at idle-PMD of the gas turbine engine can be 0.118, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, 0.17, 0.175, 0.178, or within any defined range between any two of these values.

[0045] According to a second aspect, a gas turbine engine for an aircraft is provided, comprising any of the following characteristics:

[0046] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0047] in which:

[0048] A second nvPM emission index ratio at idle-PMD is defined as:

[0049] [Math.3] Elidle SAF / pr / 1 niaxTU. SAF EIrelent'-re / E^To.PF

[0050] where:

[0051] Ê / raienti ,saf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for given operating conditions and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0052] £'7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions under which EIialeaü jSaf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0053] Ê / raienti jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for the same given operating conditions to which EIalenü ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[0054] ^fmaxTojr is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 100% of the available thrust for the same given operating conditions under which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[0055] the second ratio of the nvPM emission index at idle to PMD of the gas turbine engine is less than 1; and

[0056] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0057] The second nvPM idle-PMD emission index ratio defined in the second aspect can be as defined above in relation to the first aspect.

[0058] According to a third aspect, a method of operating the gas turbine engine of the first aspect or of the second aspect is provided, the method comprising supplying fuel including a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0059] According to a fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0060] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0061] in which:

[0062] a first nvPM emission index ratio at idle-PMD can be defined as :

[0063] [Math.4] Slow motion ^^maxTO

[0064] where:

[0065] Æ' / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[0066] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the given operating conditions; and

[0067] the first NVPM-PMD emission index ratio of the gas turbine engine at idle is less than 3; and

[0068] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0069] The first nvPM emission index ratio at idle-PMD can be as defined above in relation to the first aspect.

[0070] A second nvPM emission index ratio at idle-PMD can be defined as:

[0071] [Math.5] felt it. SAF / P] / CimaxTC'. S AF

[0072] where:

[0073] Æ' / raienti ,saf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for the given operating conditions, or for different given operating conditions, and whether a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0074] ^7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at about 100% of available thrust for the same given operating conditions at which £7raiti ,saf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0075] Ê / raienti jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for the same given operating conditions under which EIràleaü jSaf is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[0076] £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 100% of available thrust under the same given operating conditions under which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel; and in which

[0077] the second nvPM-PMD emission index ratio of the gas turbine engine at idle may be less than 1.

[0078] The second nvPM emission index ratio at idle-PMD can be as defined above in relation to the first aspect.

[0079] According to a fifth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0080] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0081] in which:

[0082] A second nvPM emission index ratio at idle-PMD can be defined as:

[0083] [Math.6] Ehaieiai SAF / p[ - , „ / L'maxTO. SAF FF / Elmxsnl l,p

[0084] where:

[0085] Ê / raienti ,saf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for given operating conditions and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0086] £7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which EIialeaü jSaf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[0087] Ê / raienti jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for the same given operating conditions to which EIalenü ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[0088] ^fmaxTojr is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 100% of the available thrust for the same given operating conditions at which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[0089] the second ratio of the nvPM emission index at idle to PMD of the gas turbine engine is less than 1; and

[0090] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0091] The second nvPM idle-PMD emission index ratio can be as defined above in relation to the first aspect.

[0092] According to a sixth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0093] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles in the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles in the second subset of fuel spray nozzles, wherein the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0094] in which:

[0095] a fuel flow rate nvPM emission index ratio can be defined as :

[0096] [Math.7] El rgjenti*W f,ralenti El,- . , : X Wf, maxTO

[0097] where:

[0098] Æ' / raienti is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions;

[0099] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the given operating conditions;

[0100] Wf raienn is the fuel flow rate to the fuel spray nozzles in kg / s at approximately 7% of the thrust available for the given operating conditions; and

[0101] WffnaxTO is the fuel flow rate to the fuel spray nozzles in kg / s at approximately 100% of the thrust available for the given operating conditions;

[0102] the nvPM emission index ratio of the gas turbine engine fuel flow rate is less than 0.3; and

[0103] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0104] The nvPM emission index ratio of the fuel flow may be less than 0.241 and preferably may be less than 0.221 and more preferably may be less than 0.201.

[0105] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.15 and preferably less than or equal to 0.1 and more preferably less than or equal to 0.05.

[0106] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.0357 and preferably may be less than or equal to 0.0327 and more preferably may be less than or equal to 0.0297.

[0107] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.0285 and preferably may be less than or equal to 0.0261 and more preferably may be less than or equal to 0.0238.

[0108] The nvPM emission index ratio of the fuel flow may be greater than or equal to 0.0138 and preferably may be greater than or equal to 0.0156 and more preferably may be less than or equal to 0.0173.

[0109] The nvPM emission index ratio of the fuel flow may be greater than or equal to 0.0189 and preferably may be greater than or equal to 0.0213 and more preferably may be less than or equal to 0.0237.

[0110] The nvPM emission index ratio of the fuel flow can be in the range of 0.0138 to 0.0357 and preferably in the range of 0.0156 to 0.0327 and even more preferably in the range of 0.0173 to 0.0297.

[0111] The nvPM emission index ratio of the fuel flow can be in the range of 0.0189 to 0.0285 and preferably in the range of 0.0213 to 0.0261 and even more preferably in the range of 0.0237 to 0.0238.

[0112] The NvPM emission index ratio of the fuel flow rate may be less than 0.003, 0.004, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.245, 0.35, 0.357 or any defined range between any two of these values.

[0113] Wf, idling. May be in the range of 0.142 to 0.263 kg / s and preferably may be in the range of 0.160 to 0.241 kg / s and more preferably can be in the range of 0.178 to 0.219 kg / s.

[0114] Wf^axTO May be in the range of 1.50 to 3.36 kg / s and preferably may be in the range of 1.69 to 3.08 kg / s and more preferably can be in the range of 1.88 to 2.80 kg / s.

[0115] According to a seventh aspect, a method of operating the gas turbine engine of the sixth aspect is provided, the method comprising supplying fuel including a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0116] According to an eighth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0117] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate in a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0118] in which:

[0119] A fuel flow rate nvPM emission index ratio can be defined as:

[0120] [Math.8] slow motion^^f slow motion maxTC^ maxTO

[0121] where:

[0122] Æ' / raienti is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for given operating conditions;

[0123] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the given operating conditions;

[0124] Wft raiti is the fuel flow to the fuel spray nozzles in kg / s at approximately 7% of the thrust available for the given operating conditions; and

[0125] WfjnaxTO is the fuel flow rate to the fuel spray nozzles in kg / s at approximately 100% of the thrust available for the given operating conditions; and

[0126] the nvPM emission index ratio of the gas turbine engine fuel flow rate is less than 0.3; and

[0127] in which the method comprises supplying fuel including sustainable aviation fuel to the plurality of fuel spray nozzles.

[0128] Any ratio of nvPM emission index of fuel flow, Wf rajeatj and Wf maxTO May be as defined above in relation to the sixth aspect.

[0129] According to a ninth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0130] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate in a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0131] in which:

[0132] A thrust nvPM emission index ratio can be defined as:

[0133] [Math.9] ^^niaxTo / F / / p , y ralGàti

[0134] where:

[0135] Æ' / raienti is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at about 7% of the available thrust for given operating conditions;

[0136] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the given operating conditions;

[0137] FmaxTO is 'the thrust of the gas turbine engine at approximately 100% of the thrust available in kN under the given operating conditions; and

[0138] F idle is 'a Gas turbine engine thrust at about 7% of thrust available in kN under the given operating conditions;

[0139] the nvPM thrust emission index ratio is greater than 0.02; and

[0140] the gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0141] The nvPM thrust emission index ratio may be greater than 0.0264 and preferably may be greater than 0.0297 and more preferably may be greater than 0.033.

[0142] The nvPM thrust emission index ratio may be greater than 0.0312 and preferably may be greater than 0.0351 and more preferably may be greater than 0.039.

[0143] The nvPM thrust emission index ratio may be greater than or equal to 0.07 and preferably may be greater than or equal to 0.1 and more preferably may be greater than or equal to 0.13.

[0144] The nvPM thrust emission index ratio may be greater than or equal to 0.178 and preferably may be greater than or equal to 0.2 and more preferably may be greater than or equal to 0.223.

[0145] The nvPM thrust emission index ratio may be greater than or equal to 0.21 and preferably may be greater than or equal to 0.237 and more preferably may be greater than or equal to 0.263.

[0146] The nvPM thrust emission index ratio may be less than or equal to 0.365 and preferably may be less than or equal to 0.335 and more preferably may be less than or equal to 0.304.

[0147] The nvPM thrust emission index ratio may be less than or equal to 0.317 and preferably may be less than or equal to 0.29 and more preferably may be less than or equal to 0.264.

[0148] The nvPM thrust emission index ratio may be in the range of 0.178 to 0.365 and preferably in the range of 0.200 to 0.335 and even more preferably in the range of 0.223 to 0.304.

[0149] The nvPM thrust emission index ratio may be in the range of 0.210 to 0.317 and preferably in the range of 0.237 to 0.290 and even more preferably in the range of 0.263 to 0.264.

[0150] The nvPM thrust emission index ratio may be greater than 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4 or any defined range between any two of these values.

[0151] The nvPM thrust emission index ratio can be 0.178, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.365 or any range defined between any two of these values.

[0152] FmaxTO May be ^ans 'a P'a8c 204 to 420 kN and preferably may be in the range of 229 kN to 385 kN and more preferably in the range of 255 kN to 350 kN.

[0153] F idle Pcut be in the range of 14.2 kN to 29.4 kN and preferably can be in the range of 16.0 kN to 26.9 kN and more preferably can be in the range of 17.8 kN to 24.5 kN.

[0154] According to a tenth aspect, a method of operating the gas turbine engine of the ninth aspect is provided, the method comprising supplying fuel including a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0155] According to an eleventh aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0156] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0157] in which:

[0158] a thrust nvPM emission index ratio can be defined as:

[0159] [Math. 10] maxTO XF / 1 inaxTO El idle / F y L idle

[0160] where:

[0161] Æ' / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[0162] Ê / maxio is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 100% of the available thrust for the given operating conditions;

[0163] FmaxTO is 'a Thrust of the gas turbine engine at approximately 100% of the available thrust in kN under the given operating conditions,

[0164] F idle is 'a Gas turbine engine thrust at about 7% of thrust available in kN under the given operating conditions; and

[0165] the nvPM thrust emission index ratio is greater than 0.02; and

[0166] The process includes the supply of fuel comprising aviation fuel durable to the plurality of fuel spray nozzles.

[0167] Any nvPM thrust emission index ratio, FniaxfO ct F idled Can be tc' 9ue defined above in relation to the ninth aspect.

[0168] According to a twelfth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0169] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0170] in which:

[0171] A depleted cruise nvPM-PMD emission index ratio can be defined as:

[0172] [Math. 11] The cruise [Impaired: / ElIrj

[0173] where:

[0174] E / cruise (impoverished e) can be defined as:

[0175] [Math. 12] PT + F1 ^-11 max T 1 m on te e 2

[0176] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust for given operating conditions;

[0177] EImontée is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust for the given operating conditions; and

[0178] BPR is the gas turbine engine dilution ratio;

[0179] the ratio of the nvPM emissions index in depleted cruise-PMD is less than 0.2;

[0180] and

[0181] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0182] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.151 and preferably may be less than 0.138 and preferably further may be less than 0.126.

[0183] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.136 and preferably may be less than 0.125, and preferably further may be less than 0.114.

[0184] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.131, preferably may be less than or equal to 0.12, and preferably further may be less than or equal to 0.109.

[0185] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.118, preferably may be less than or equal to 0.108, and preferably further may be less than or equal to 0.098.

[0186] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.0751, preferably may be greater than or equal to 0.0845, and preferably furthermore may be greater than or equal to 0.0938.

[0187] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.0869, preferably may be greater than or equal to 0.0977, and preferably furthermore may be greater than or equal to 0.108.

[0188] The nvPM emission index ratio in depleted cruise-PMD may be in the range of 0.0751 to 0.131, preferably may be in the range of 0.0845 to 0.120 and preferably further may be in the range of 0.0938 to 0.109.

[0189] The nvPM emission index ratio in depleted cruise-PMD may be in the range of 0.0751 to 0.118, preferably may be in the range of 0.0845 to 0.108 and preferably further may be in the range of 0.0938 to 0.0980.

[0190] The nvPM emission index ratio in depleted cruise-PMD may be in the range of 0.0869 to 0.131, preferably may be in the range of 0.0977 to 0.120 and preferably further may be in the range of 0.108 to 0.109.

[0191] The depleted cruise nvPM-PMD emission index ratio may be less than 0.098, 0.11, 0.115, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, 0.17, 0.175, 0.18, 0.185, 0.19, 0.195 or 0.2, or within any defined range between any two of these values.

[0192] The depleted cruise nvPM-PMD emission index ratio can be 0.0751, 0.08, 0.085, 0.09, 0.095, 0.1, 0.105, 0.11, 0.115, 0.12, 0.125, 0.13, 0.131, or within any defined range between any two of these values.

[0193] A rich cruise nvPM-PMD emission index ratio can be defined as:

[0194] [Math. 13] The cruise (rich) / pi __ BPR

[0195] where:

[0196] EIaoisiè[e (rich) can be defined as:

[0197] [Math. 14] pr, +FT, 1 approach 2

[0198] EImontée is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 85% of the available thrust for the given operating conditions, or for other different operating conditions;

[0199] Ί / approach is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EImontée is calculated; and

[0200] S / maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée is calculated; and in which

[0201] The rich cruise nvPM-PMD emission index ratio may be less than 0.3.

[0202] The rich cruise nvPM-PMD emission index ratio may be less than 0.29, preferably may be less than 0.266 and preferably furthermore may be less than 0.242.

[0203] The rich cruise nvPM-PMD emission index ratio may be less than 0.285, preferably may be less than 0.261 and preferably further may be less than 0.237.

[0204] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.2, preferably may be less than or equal to 0.16, and preferably further may be less than or equal to 0.12.

[0205] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.105, preferably may be less than or equal to 0.0963, and preferably further may be less than or equal to 0.0875.

[0206] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.102, preferably may be less than or equal to 0.0926, and preferably further may be less than or equal to 0.0842.

[0207] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.0509, preferably may be greater than or equal to 0.0573, and preferably further may be greater than or equal to 0.0637.

[0208] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.0699, preferably may be greater than or equal to 0.0787, and preferably further may be greater than or equal to 0.0874.

[0209] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0509 to 0.105, preferably may be in the range of 0.0573 to 0.0963 and preferably further may be in the range of 0.0637 to 0.0875.

[0210] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0509 to 0.102, preferably may be in the range of 0.0573 to 0.0926 and preferably further may be in the range of 0.0637 to 0.0842.

[0211] The rich-PMD nvPM emission index ratio may be in the range of 0.0699 to 0.105, preferably may be in the range of 0.0787 to 0.0963 and preferably further may be in the range of 0.0874 to 0.0875.

[0212] The rich cruise nvPM-PMD emission index ratio may be less than 0.3, 0.28, 0.26, 0.24, 0.22, 0.2, 0.18, 0.16, 0.14, 0.12, 0.1, 0.0842, or within any defined range between any two of these values.

[0213] The rich cruise nvPM-PMD emission index ratio may be 0.0509, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.105, or within any defined range between any two of these values.

[0214] The BPR may be in the range of 6.38 to 11.3 and preferably in the range of 7.18 to 10.4 and preferably further in the range of 7.98 to 9.40.

[0215] The BPR may be in the range of 6.38 to 9.59 and preferably may be in the range of 7.18 to 8.79 and preferably further in the range of 7.98 to 7.99.

[0216] The BPR may be in the range of 6.85 to 11.3 and preferably may be in the range of 7.70 to 10.4 and preferably further may be in the range of 8.56 to 9.40.

[0217] According to a thirteenth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0218] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the nozzles fuel spray nozzles of the first subset of fuel spray nozzles are supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0219] in which:

[0220] A rich cruise nvPM-PMD emission index ratio can be defined as:

[0221] [Math. 15] BPR

[0222] where:

[0223] ^^cruise (rich) can be defined as:

[0224] [Math. 16] El - +EI > ascent^^1 approach 2

[0225] £7mOntée is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions;

[0226] ^fapproach is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EImontée is calculated; and

[0227] Ê / maxio is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée is calculated; and

[0228] the ratio of the nvPM emissions index in rich cruise to PMD is less than 0.3; and

[0229] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0230] The rich cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the twelfth aspect.

[0231] According to a fourteenth aspect, a method of operating the gas turbine engine of the twelfth or thirteenth aspect is provided, the method comprising supplying fuel including a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0232] According to a fifteenth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0233] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0234] in which:

[0235] A depleted cruise nvPM-PMD emission index ratio can be defined as:

[0236] [Math. 17] The cruise (impoverished^ / PI — ' 7 '-^niaxTO BPR

[0237] where:

[0238] ^ / cruise (impoverished) can be defined as:

[0239] [Math. 18] 17T 4-FI ■ 1 mAX T O'-*-'1 fii on te e 2

[0240] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust for given operating conditions;

[0241] Ê / climb is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust for the given operating conditions; and

[0242] BPR is the gas turbine engine dilution ratio; and

[0243] the ratio of the nvPM emissions index in depleted cruise-PMD is less than 0.2; and

[0244] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0245] The depleted cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the twelfth aspect.

[0246] A rich cruise nvPM-PMD emission index ratio can be defined as:

[0247] [Math. 19] BPR

[0248] where:

[0249] ^' / cruise (rich) Pcut can be defined as:

[0250] [Math.20] El - +EI > ascent^^1 approach 2

[0251] £7mOntée is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of the available thrust for the given operating conditions, or for other different operating conditions;

[0252] ^fapproach is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions under which EImontée is calculated;

[0253] £7maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée is calculated; and in which

[0254] The rich cruise nvPM-PMD emission index ratio may be less than 0.3.

[0255] The rich cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the twelfth aspect.

[0256] According to a sixteenth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0257] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to The number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0258] in which:

[0259] A rich cruise nvPM-PMD emission index ratio can be defined as:

[0260] [Math.21] The cruise (rich) / Fl __ BPR

[0261] where:

[0262] £' / Cruise (rich) can be defined as:

[0263] [Math.22] pr - +FT , 1 approach 2

[0264] Æ' / climb is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for given operating conditions;

[0265] ^fapproach is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions under which EImontée is calculated;

[0266] £7maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée is calculated; and

[0267] the ratio of the nvPM emissions index in rich cruise to PMD is less than 0.3; and

[0268] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0269] The rich cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the twelfth aspect.

[0270] According to a seventeenth aspect, a gas turbine engine for an aircraft is supplied, including any of the following characteristics:

[0271] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of nozzles. fuel spraying, wherein the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0272] in which:

[0273] A PMD nvPM emission index ratio can be defined as:

[0274] [Math.23] ElmaxTO. SAF EIniaxTO.FF

[0275] where:

[0276] ^7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0277] £7maXTo,FF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[0278] the nvPM PMD emission index ratio of the gas turbine engine is less than 1; and

[0279] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0280] The nvPM PMD emission index ratio may be greater than zero.

[0281] The PMD nvPM emission index ratio may be less than or equal to 0.93, and preferably may be less than or equal to 0.86, and more preferably may be less than or equal to 0.79.

[0282] The nvPM PMD emission index ratio may be less than or equal to 0.776, and preferably may be less than or equal to 0.711, and more preferably may be less than or equal to 0.646.

[0283] The nvPM PMD emission index ratio may be greater than or equal to 0.15, and preferably may be greater than or equal to 0.3, and more preferably may be greater than or equal to 0.45.

[0284] The nvPM PMD emission index ratio may be greater than or equal to 0.516, and preferably may be greater than or equal to 0.581, and more preferably may be greater than or equal to 0.645.

[0285] The nvPM PMD emission index ratio may be in the range of 0.516 to 0.776, and preferably may be in the range of 0.581 to 0.711, and more preferably may be in the range of 0.645 to 0.646.

[0286] The nvPM PMD emission index ratio of the gas turbine engine may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any defined range between any two of these values.

[0287] The PMD nvPM emission index ratio may be 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, or within any range defined between any two of these values.

[0288] A rise nvPM emission index ratio can be defined as:

[0289] [Math.24] The climb, SAP pj *niontee,FF

[0290] where:

[0291] Ê / climb,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0292] Ί / rise jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same given operating conditions at which EIrise jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[0293] and in which the climb nvPM emission index ratio of the gas turbine engine may be less than 1.

[0294] The rise nvPM emission index ratio may be greater than zero.

[0295] The rise nvPM emission index ratio may be less than or equal to 0.9, and preferably may be less than or equal to 0.75, and more preferably may be less than or equal to 0.6.

[0296] The rise nvPM emission index ratio may be less than or equal to 0.57, and preferably may be less than or equal to 0.523, and more preferably may be less than or equal to 0.475.

[0297] The rise nvPM emission index ratio may be greater than or equal to 0.1, and preferably may be greater than or equal to 0.2, and more preferably may be greater than or equal to 0.3.

[0298] The rise nvPM emission index ratio may be greater than or equal to 0.379, and preferably may be greater than or equal to 0.427, and more preferably may be greater than or equal to 0.474.

[0299] The rise nvPM emission index ratio may be in the range of 0.379 to 0.570, and preferably may be in the range of 0.427 to 0.523, and more preferably may be in the range of 0.474 to 0.475.

[0300] The climb nvPM emission index ratio of the gas turbine engine may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any range defined between any two of these values.

[0301] The rise nvPM emission index ratio may be 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, or within any defined range between any two of these values.

[0302] An approach nvPM emission index ratio can be defined as:

[0303] [Math.25] PT it" i r1 1 approach, SAP EJ approçh e, FF

[0304] where:

[0305] £7 approach, SAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0306] Δ / approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which Δ7approach ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[0307] and in which the approach nvPM emission index ratio of the gas turbine engine may be less than 1.

[0308] The approach nvPM emission index ratio may be greater than zero.

[0309] The approach nvPM emission index ratio may be less than or equal to 0.8, and preferably may be less than or equal to 0.5, and more preferably may be less than or equal to 0.2.

[0310] The approach nvPM emission index ratio may be less than or equal to 0.185, and preferably may be less than or equal to 0.169, and more preferably may be less than or equal to 0.154.

[0311] The approach nvPM emission index ratio may be greater than or equal to 0.03, and preferably may be greater than or equal to 0.06, and more preferably may be greater than or equal to 0.09.

[0312] The approach nvPM emission index ratio may be greater than or equal to 0.122, and preferably may be greater than or equal to 0.138, and more preferably may be greater than or equal to 0.153.

[0313] The approach nvPM emission index ratio may be in the range of 0.122 to 0.185, and preferably may be in the range of 0.138 to 0.169, and more preferably may be in the range of 0.153 to 0.154.

[0314] The approach nvPM emission index ratio of the gas turbine engine may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any range defined between any two of these values.

[0315] The approach nvPM emission index ratio may be 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or within any defined range between any of these values.

[0316] An nvPM emission index ratio at idle can be defined as:

[0317] [Math.26] ralen ti. SAP Elfalenti.FP

[0318] where:

[0319] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust for given operating conditions, or for different given operating conditions, and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0320] Δ / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which ELaiemi ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[0321] and in which the nvPM emission index ratio at idle of the gas turbine engine may be less than 1.

[0322] The nvPM emission index ratio at idle may be greater than zero.

[0323] The nvPM emission index ratio at idle may be less than or equal to 0.8, and preferably may be less than or equal to 0.5, and more preferably may be less than or equal to 0.2.

[0324] The nvPM emission index ratio at idle may be less than or equal to 0.115, and preferably may be less than or equal to 0.106, and more preferably may be less than or equal to 0.0959.

[0325] The nvPM emission index ratio at idle may be greater than or equal to 0.02, and preferably may be greater than or equal to 0.04, and more preferably may be greater than or equal to 0.06.

[0326] The nvPM emission index ratio at idle may be greater than or equal to 0.0766, and preferably may be greater than or equal to 0.0862, and more preferably may be greater than or equal to 0.0958.

[0327] The nvPM emission index ratio at idle may be in the range of 0.0766 to 0.115, and preferably may be in the range of 0.0862 to 0.106, and more preferably may be in the range of 0.0958 to 0.0959.

[0328] The nvPM emission index ratio at idle may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any defined range between any two of these values.

[0329] The nvPM emission index ratio at idle of the gas turbine engine can be 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, or within a defined range between any two of these values.

[0330] According to an eighteenth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0331] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0332] in which:

[0333] A rise nvPM emission index ratio can be defined as:

[0334] [Math.27] SAF Elniontée.FF

[0335] where:

[0336] £7,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0337] £7montée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same given operating conditions at which EImontée jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[0338] and the climb nvPM emission index ratio of the gas turbine engine may be less than 1; and

[0339] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0340] The rise nvPM emission index ratio can be as defined in relation to the seventeenth aspect.

[0341] According to a nineteenth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0342] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0343] in which:

[0344] An approach nvPM emission index ratio can be defined as:

[0345] [Math.28] EI approach, SAP EIapproçh e.FF

[0346] where:

[0347] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0348] £7approx. jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which £7approx. ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0349] the approach nvPM emission index ratio of the gas turbine engine is less than 1; and

[0350] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0351] The approach nvPM emission index ratio may be as defined above in relation to the seventeenth aspect.

[0352] According to a twentieth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0353] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0354] in which:

[0355] An NVPM emission index ratio at idle can be defined as:

[0356] [Math.29] SAF EIralenti,FP

[0357] where:

[0358] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0359] Ê / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which EIialeaü jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0360] the nvPM emission index ratio at idle of the gas turbine engine is less than 1; and

[0361] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0362] The nvPM emission index ratio at idle can be as defined in relation to the seventeenth aspect.

[0363] According to a twenty-first aspect, a method of operating the gas turbine engine of any of the seventeenth, eighteenth, nineteenth or twentieth aspects is provided, the method comprising supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0364] According to a twenty-second aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0365] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to The number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and

[0366] A PMD nvPM emission index ratio can be defined as:

[0367] [Math.30] ElmaxTO, SAF EïmaxTQ.PF

[0368] where:

[0369] £7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0370] £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0371] the nvPM PMD emission index ratio of the gas turbine engine (10) is less than 1; and

[0372] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0373] The nvPM PMD emission index ratio can be as defined in relation to the seventeenth aspect.

[0374] A rise nvPM emission index ratio can be defined as:

[0375] [Math.31] UT 1 montéo, SAF ^2müntee,FF

[0376] where:

[0377] £7,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0378] £7montée ,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same given operating conditions at which EImontée >Saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[0379] The nvPM climb emission index ratio of the gas turbine engine may be less than 1.

[0380] The rise nvPM emission index ratio can be as defined in relation to the seventeenth aspect.

[0381] An approach nvPM emission index ratio can be defined as:

[0382] [Math.32] The approach, SAP The approach, FF

[0383] where:

[0384] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0385] £7approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which £7approach ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[0386] and in which the approach nvPM emission index ratio of the gas turbine engine may be less than 1.

[0387] The approach nvPM emission index ratio may be as defined in relation to the seventeenth aspect.

[0388] An nvPM emission index ratio at idle can be defined as:

[0389] [Math.33] The slowdown, SAP Elralenti.PF

[0390] where:

[0391] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust for given operating conditions, or for different given operating conditions, and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0392] Ê / raienti ,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which ELaiemi ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[0393] and in which the nvPM emission index ratio at idle of the gas turbine engine may be less than 1.

[0394] The nvPM emission index ratio at idle can be as defined in relation to the seventeenth aspect.

[0395] According to a twenty-third aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0396] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0397] a rise nvPM emission index ratio can be defined as:

[0398] [Math.34] The climb, SAP pj *niontee,FF

[0399] where:

[0400] Ê / climb,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0401] Ί / rise jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same given operating conditions at which EIrise jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[0402] the gas turbine engine's climb nvPM emission index ratio is less than 1; and

[0403] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0404] The rise nvPM emission index ratio can be as defined in relation to the seventeenth aspect.

[0405] According to a twenty-fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0406] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0407] an approach nvPM emission index ratio can be defined as:

[0408] [Math.35] EIapproche, SAP EI approche,FF

[0409] where:

[0410] £7approche,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0411] Δ / approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which Δ7approach ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0412] the approach nvPM emission index ratio of the gas turbine engine is less than 1; and

[0413] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0414] The approach nvPM emission index ratio may be as defined in relation to the seventeenth aspect.

[0415] According to a twenty-fifth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0416] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0417] an nvPM emission index ratio at idle can be defined as:

[0418] [Math.36] Elraienti, SAP E^ralenH, F'F

[0419] where:

[0420] Æ' / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[0421] Æ' / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0422] the nvPM emission index ratio at idle of the gas turbine engine is less than 1; and

[0423] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0424] The nvPM emission index ratio at idle can be as defined in relation to the seventeenth aspect.

[0425] According to a twenty-sixth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0426] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and,

[0427] in which:

[0428] A fuel flow rate modified by an nvPM PMD emission index ratio can be defined as:

[0429] [Math.37] ElmaxTO, SAF ta r EI^TO.FF

[0430] where:

[0431] ^7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF);

[0432] £7maXTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0433] IVf^axTO is the mass flow rate of fuel supplied to the plurality of fuel spray nozzles in kg / s when the gas turbine engine is operating at about 100% of the thrust available for the given operating conditions;

[0434] the fuel flow rate modified by a gas turbine engine's nvPM PMD emission index ratio in kg / s is less than 4; and

[0435] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0436] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than zero.

[0437] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than 3.36, more preferably may be less than 3.08 and even more preferably may be less than 2.8.

[0438] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 0.974, preferably may be greater than or equal to 1.09 and preferably further may be greater than or equal to 1.21.

[0439] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 2.17, more preferably may be less than or equal to 1.99 and preferably further may be less than or equal to 1.81.

[0440] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s can be in the range of 0.974 to 2.17, preferably can be in the range of 1.09 to 1.99 and preferably further can be in the range of 1.21 to 1.81.

[0441] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than 2.95, more preferably may be less than 2.7 and even more preferably may be less than 2.46.

[0442] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 1.26, preferably may be greater than or equal to 1.42 and preferably further may be greater than or equal to 1.58.

[0443] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 1.91, more preferably may be less than or equal to 1.75 and preferably further may be less than or equal to 1.59.

[0444] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s can be in the range of 1.26 to 1.91, preferably can be in the range of 1.42 to 1.75 and preferably further can be in the range of 1.58 to 1.59.

[0445] The fuel flow rate modified by an emission index ratio of nvPM PMD of the gas turbine engine in kg / s can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.974, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.17, or within any defined range between any two of these values.

[0446] PVfjnaxTO May be in the range of 1.50 to 3.36 kg / s and preferably may be in the range of 1.69 to 3.08 kg / s and more preferably can be in the range of 1.88 to 2.80 kg / s.

[0447] PVf^naxTO May be in the range of 1.96 to 2.95 kg / s and preferably may be in the range of 2.20 to 2.70 kg / s and more preferably can be in the range of 2.45 to 2.46 kg / s.

[0448] A fuel flow rate modified by a climb nvPM emission index ratio can be defined as:

[0449] [Math.38] inontSe, SAF T 4 Z EImantée,FF XW fJUOIltée

[0450] where:

[0451] Ê / climb,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0452] Δ / rise jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which ΔE / rise jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0453] Wf bridged is 'c mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at approximately 85% of available thrust under the same operating conditions under which EImontée, Sai and EImontée >FF are calculated; and in which

[0454] the fuel flow modified by a ratio of the nvPM of climb of the gas turbine engine in kg / s may be less than 3.

[0455] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than zero.

[0456] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 2.73, more preferably may be less than 2.5 and even more preferably may be less than 2.27.

[0457] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 0.589, preferably may be greater than or equal to 0.663 and preferably further may be greater than or equal to 0.737.

[0458] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.3, more preferably may be less than or equal to 1.19 and preferably further may be less than or equal to 1.08.

[0459] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s can be in the range of 0.589 to 1.30, preferably can be in the range of 0.663 to 1.19 and preferably further can be in the range of 0.737 to 1.08.

[0460] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 2.42, more preferably may be less than 2.21 and even more preferably may be less than 2.01.

[0461] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 0.763, preferably may be greater than or equal to 0.858 and preferably further may be greater than or equal to 0.953.

[0462] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.15, more preferably may be less than or equal to 1.05 and preferably further may be less than or equal to 0.954.

[0463] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s can be in the range of 0.763 to 1.15, preferably can be in the range of 0.858 to 1.05 and preferably further can be in the range of 0.953 to 0.954.

[0464] The fuel flow modified by an emission index ratio of nvPM of climb of the gas turbine engine in kg / s may be less than or equal to 0.589, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, or any range defined between any two of these values.

[0465] Wfpontée May be in the range of 1.24 to 2.73 kg / s and preferably may be in the range of 1.39 to 2.50 kg / s and more preferably can be in the range of 1.55 to 2.27 kg / s.

[0466] Wf bridged can be in the range of 1.60 to 2.42 kg / s and preferably can be in the range of 1.80 to 2.21 kg / s and more preferably can be in the range of 2.00 to 2.01 kg / s.

[0467] A fuel flow rate modified by an approach nvPM emission index ratio can be defined as:

[0468] [Math.39] The approach, SAF T4Z The approach,FF f,appiOChe

[0469] where:

[0470] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of the available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0471] £7approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which £7aPProche ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0472] Wf approaches constant 'c mass flow rate of fuel supplied to the plurality of nozzles fuel spray in kg / s when the gas turbine engine is operating at approximately 30% of available thrust under the same operating conditions under which £7approach, saf and £7approach jf are calculated; and in which

[0473] the fuel flow modified by an approach nvPM emission index ratio of the gas turbine engine in kg / s is less than 0.9.

[0474] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be greater than zero.

[0475] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 0.841, more preferably may be less than 0.771 and even more preferably may be less than 0.701.

[0476] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be greater than or equal to 0.0636, preferably may be greater than or equal to 0.0716 and preferably further may be greater than or equal to 0.0795.

[0477] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.13, more preferably may be less than or equal to 0.119 and preferably further may be less than or equal to 0.108.

[0478] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be in the range of 0.0636 to 0.130, preferably may be in the range of 0.0716 to 0.119 and preferably further may be in the range of 0.0795 to 0.108.

[0479] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 0.771, more preferably may be less than 0.707 and even more preferably may be less than 0.642.

[0480] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be greater than or equal to 0.0788, preferably may be greater than or equal to 0.0887 and preferably further may be greater than or equal to 0.0986.

[0481] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.119, more preferably may be less than or equal to 0.109 and preferably further may be less than or equal to 0.0987.

[0482] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be in the range of 0.0788 to 0.119, preferably may be in the range of 0.0887 to 0.109 and preferably also can be in the range of 0.0986 to 0.0987.

[0483] The fuel flow modified by an approach nvPM emission index ratio of the gas turbine engine in kg / s may be less than or equal to 0.0636, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.105, 0.12, 0.125, 0.13, or any range defined between any two of these values.

[0484] TVf approach may be in the range of 0.414 to 0.841 kg / s and preferably may be in the range of 0.466 to 0.771 kg / s and more preferably can be in the range of 0.517 to 0.701 kg / s.

[0485] Wf approach May be in the range of 0.513 to 0.771 kg / s and preferably may be in the range of 0.577 to 0.707 kg / s and more preferably can be in the range of 0.641 to 0.642 kg / s.

[0486] A fuel flow rate modified by an nvPM emission index ratio at idle can be defined as:

[0487] [Math.40] The slowdown, SAF Ta r Slowing down X Wfralenti

[0488] where:

[0489] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of the available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0490] Δ / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which Δ7raienti ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0491] IVf idle is 'c mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at approximately 7% of the available thrust under the same operating conditions at which idle, saf and ELaienti, ff are calculated; and in which

[0492] the fuel flow modified by an emission index ratio of nvPM at idle of the gas turbine engine in kg / s may be less than 0.3.

[0493] The fuel flow rate modified by an emission index ratio of nvPM at idle in kg / s may be greater than zero.

[0494] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be less than 0.263, more preferably may be less than 0.241 and even more preferably may be less than 0.219.

[0495] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be greater than or equal to 0.0136, preferably may be greater than or equal to 0.0153 and preferably further may be greater than or equal to 0.017.

[0496] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be less than or equal to 0.0252, more preferably may be less than or equal to 0.0231 and preferably further may be less than or equal to 0.021.

[0497] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be in the range of 0.0136 to 0.0252, preferably may be in the range of 0.0153 to 0.0231 and preferably further may be in the range of 0.0170 to 0.0210.

[0498] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be less than 0.263, more preferably may be less than 0.241 and even more preferably may be less than 0.219.

[0499] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be greater than or equal to 0.0167, preferably may be greater than or equal to 0.0188 and preferably further may be greater than or equal to 0.0209.

[0500] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be less than or equal to 0.0252, more preferably may be less than or equal to 0.0231 and preferably further may be less than or equal to 0.021.

[0501] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be in the range of 0.0167 to 0.0252, preferably may be in the range of 0.0188 to 0.0231 and preferably further may be in the range of 0.0209 to 0.0210.

[0502] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be less than 0.253, more preferably may be less than 0.232 and even more preferably may be less than 0.211.

[0503] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be greater than or equal to 0.0136, preferably may be greater than or equal to 0.0153 and preferably further may be greater than or equal to 0.017.

[0504] The fuel flow modified by an emission index ratio of nvPM at idle in kg / s may be less than or equal to 0.0243, more preferably may be less than or equal to 0.0223 and preferably further may be less than or equal to 0.0202.

[0505] The fuel flow rate modified by an emission index ratio of nvPM at idle in kg / s may be in the range of 0.0136 to 0.0243, preferably may be in the range of 0.0153 to 0.0223 and preferably also can be in the range of 0.0170 to 0.0202.

[0506] The fuel flow rate modified by an emission index ratio of nvPM at idle of the gas turbine engine in kg / s may be less than or equal to 0.0136, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.02, 0.021, 0.022, 0.023, 0.024, 0.025, 0.0252, or any range defined between any two of these values.

[0507] IVfiaient! may be in the range of 0.142 to 0.263 kg / s, and preferably may be in the range of 0.160 to 0.241 kg / s and more preferably can be in the range of 0.178 to 0.219 kg / s.

[0508] IVfj-aienti can be in the range of 0.142 to 0.253 kg / s and preferably can be in the range of 0.160 to 0.232 kg / s and more preferably can be in the range of 0.178 to 0.211 kg / s.

[0509] IV f idle speed can be in the range of 0.175 to 0.263 kg / s and preferably can be in the range of 0.196 to 0.241 kg / s and more preferably can be in the range of 0.218 to 0.219 kg / s.

[0510] According to a twenty-seventh aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0511] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0512] A fuel flow rate modified by a climb nvPM emission index ratio can be defined as:

[0513] [Math.41] xf^nontee

[0514] where:

[0515] £7 rise, saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel; and

[0516] Elmontée FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EImontée jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0517] Wf bridged is 'c mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at about 85% of the available thrust for the same operating conditions under which EImontée Sai and EImontée >FF are calculated;

[0518] the fuel flow rate modified by a ratio of the nvPM of climb of the gas turbine engine in kg / s is less than 3; and

[0519] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0520] The fuel flow modified by a climb nvPM emission index ratio and / or IL may be as defined above in relation to the twenty- sixth aspect.

[0521] According to a twenty-eighth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0522] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0523] A fuel flow rate modified by an approach nvPM emission index ratio can be defined as:

[0524] [Math.42] EI approach, SAF X Wfrapproche

[0525] where:

[0526] ^ / approach,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for the given operating conditions, or for different operating conditions, and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0527] £7approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which £7approach ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0528] TVf approach is the mass flow rate of fuel supplied to the plurality of nozzles fuel spray in kg / s when the gas turbine engine is operating at approximately 30% of available thrust under the same operating conditions under which £7approach, saf and £7approach jf are calculated; and in which

[0529] the fuel flow rate modified by an approach nvPM emission index ratio of the gas turbine engine in kg / s is less than 0.9; and

[0530] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0531] The fuel flow modified by an approach nvPM and / or approach IVf emission index ratio may be as defined above in relation to the twenty-sixth aspect.

[0532] According to a twenty-ninth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0533] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0534] A fuel flow rate modified by an NVPM emission index ratio at idle can be defined as:

[0535] [Math.43] £Iraienti, SAP rir ElralentiFF XW f Slow Motion

[0536] where:

[0537] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0538] Δ / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which ΔIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0539] W is the mass flow rate of fuel supplied to the plurality of fuel spray nozzles in kg / s when the gas turbine engine is operating at about 7% of the available thrust for the same operating conditions at which idle, SAF and idle JF are calculated;

[0540] the fuel flow rate modified by an emission index ratio of nvPM at idle of the gas turbine engine in kg / s is less than 0.3; and

[0541] The gas turbine engine is designed to supply fuel including a SAF to the plurality of fuel spray nozzles.

[0542] The fuel flow modified by an emission index ratio of nvPM at idle and / or Wfiaient! May be as defined above in relation to the twenty-sixth aspect.

[0543] According to a thirtieth aspect, a method of operating the gas turbine engine of any one or more of the twenty-sixth, twenty-seventh, twenty-eighth or twenty-ninth aspects is provided, the method comprising supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[0544] According to a thirty-first aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0545] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the device

[0546]

[0547]

[0548]

[0549]

[0550]

[0551]

[0552]

[0553]

[0554]

[0555]

[0556] combustor can operate under a condition in which each of the fuel spray nozzles in the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles in the second subset of fuel spray nozzles, in which a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: A fuel flow rate modified by a PMD (nvPM) emission index ratio can be defined as: [Math.44] ElmaxTO, SAF EïmaxTQ.PF ^ÿfjnaxTO Or : EI^to.saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel (SAF); £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and Wf^axTO is the mass flow rate of fuel supplied to the plurality of fuel spray nozzles in kg / s when the gas turbine engine is operating at approximately 100% of the thrust available for the given operating conditions; the fuel flow rate modified by a ratio of nvPM PMD emissions index in kg / s is less than 4; and The process includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles. The fuel flow modified by an emission index ratio of nvPM PMD and / or ïVfjnaxTO May be as defined above in relation to the twenty-sixth aspect. A fuel flow rate modified by a climb nvPM emission index ratio can be defined as:

[0557] [Math.45] SAF Elniontée.FF x Wf < ' *vf,montée

[0558] where:

[0559] Elmontée >Saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0560] £7montée jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust under the same operating conditions at which EImontée jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0561] Wfjiiontée is the mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at approximately 85% of the available thrust under the same operating conditions for which EImontée >Saf and EImontée >FF are calculated; and in which

[0562] the fuel flow modified by a ratio of the nvPM of climb of the gas turbine engine (10) in kg / s may be less than 3.

[0563] The fuel flow modified by a rise and / or IVfjnotée nvPM emission index ratio may be as defined above in relation to the twenty- sixth aspect.

[0564] A fuel flow rate modified by an nvPM emission index ratio

[0565] The approach can be defined as: [Math.46] ^approach, SAF y. - Approach.FF * VV f, approach

[0566] where:

[0567] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of the available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0568] ^ / approach ,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions to which £7aPProche ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0569] VUf approach cst 'c mass flow rate of fuel supplied to the plurality of nozzles fuel spray in kg / s when the gas turbine engine is operating at approximately 30% of available thrust under the same operating conditions under which £7approach, saf and £7approach jf are calculated; and in which

[0570] the fuel flow modified by an approach nvPM emission index ratio of the gas turbine engine (10) in kg / s may be less than 0.9.

[0571] The fuel flow modified by an approach nvPM emission index ratio and / or approach Wf Pcut be as defined above in relation to the twenty-sixth aspect.

[0572] A fuel flow rate modified by an nvPM emission index ratio at idle can be defined as:

[0573] [Math.47] The slowdown, SAF w ElralentàFF VV frRalenti

[0574] where:

[0575] £'Zraiti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of the available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0576] Æ' / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0577] W f idled 'c mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at approximately 7% of the available thrust for the same operating conditions under which ^ / idle, saf and EIaienSi jf are calculated; and in which

[0578] the fuel flow modified by an emission index ratio of nvPM at idle of the gas turbine engine in kg / s may be less than 0.3.

[0579] The fuel flow modified by an emission index ratio of nvPM at idle and / or Wf at idle may be as defined above in relation to the twenty-sixth aspect.

[0580] According to a thirty-second aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0581] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0582] A fuel flow rate modified by a climb nvPM emission index ratio can be defined as:

[0583] [Math.48] EI mounted, SAP M r EImounted,FF

[0584] where:

[0585] Ê / montée ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0586] Ί / rise jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which Ί / rise jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0587] Wfjnotée is 'c mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at about 85% of the available thrust for the same operating conditions under which EImontée Sai and EImontée >FF are calculated;

[0588] the fuel flow rate modified by a ratio of the nvPM of climb emission index of the gas turbine engine in kg / s is less than 3; and

[0589] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0590] The fuel flow modified by a climb nvPM emission index ratio and / or IVf,climbing can be as defined above in relation to the twenty-sixth aspect.

[0591] According to a thirty-third aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0592] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: ,

[0593] A fuel flow rate modified by an approach nvPM emission index ratio can be defined as:

[0594] [Math.49] The approach, SAP T4Z EIapprocheiPr X Wf,approche

[0595] where:

[0596] ^ / approach,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under given operating conditions, or under different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0597] £7approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions to which £7aPProche ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0598] Wf.approach is the mass flow rate of fuel supplied to the plurality of nozzles fuel spray in kg / s when the gas turbine engine is operating at approximately 30% of the available thrust for the same operating conditions under which ^ / approach,saf and £7approach,ff are calculated,

[0599] the fuel flow rate modified by an approach nvPM emission index ratio of the gas turbine engine in kg / s is less than 0.9; and

[0600] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0601] The fuel flow rate modified by an approach nvPM and / or IVf approach emission index ratio may be as defined above in relation to the

[0602]

[0603]

[0604]

[0605] twenty-sixth aspect. According to a thirty-fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising: a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; and in which: , A fuel flow rate modified by an NvPM emission index ratio at idle can be defined as: [Math.50] Elralenti, SAF, EIra]enpFF X VVfralenti

[0606] where:

[0607] Æ' / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0608] Æ' / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0609] IVfralenti is the mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is running at about 7% of the available thrust for the same operating conditions to which ^idle ,SAF Ct ÊLidle JF SOUt Calculated;

[0610] the fuel flow rate modified by an emission index ratio of nvPM at idle of the gas turbine engine in kg / s is less than 0.3; and

[0611] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0612] The fuel flow modified by an nvPM emission index ratio at idle and / or idle can be as defined above in relation to the twenty-sixth aspect.

[0613] According to a thirty-fifth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[0614] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6;

[0615] in which:

[0616] A depleted cruise nvPM emission index ratio can be defined as:

[0617] [Math.51] Elcroisièrdappmivi'ie), SAF fi; ' ■ ~ cruiserekimpaurri&l FP

[0618] where:

[0619] ^ / cruise (impoverished),saf can be defined as:

[0620] [Math.52] Elmax TO. SAF^ E-Bridged, SAF 2

[0621] E / cruise (impoverished e),ff can be defined as:

[0622] [Math.53] ^maxTO, FF"*" -^montée, FF 2

[0623] £' / maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0624] Ê / montée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0625] Æ / maxTOFF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0626] Ê / montée ,ff is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0627] the nvPM emission index ratio in lean cruise of the gas turbine engine is less than 1; and

[0628] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0629] The nvPM emission index ratio in depleted cruise can be greater than zero.

[0630] The nvPM emission index ratio in depleted cruise may be less than or equal to 0.9 and preferably may be less than or equal to 0.8 and preferably further may be less than or equal to 0.7.

[0631] The nvPM emission index ratio in depleted cruise may be less than or equal to 0.677, preferably may be less than or equal to 0.621 and preferably further may be less than or equal to 0.564.

[0632] The nvPM emission index ratio in depleted cruise may be greater than or equal to 0.446, preferably may be greater than or equal to 0.501 and preferably further may be greater than or equal to 0.557.

[0633] The nvPM emission index ratio in depleted cruise may be in the range of 0.446 to 0.677, preferably may be in the range of 0.501 to 0.621 and preferably further may be in the range of 0.557 to 0.564.

[0634] The nvPM emission index ratio in depleted cruise may be less than or equal to 0.673, preferably may be less than or equal to 0.617 and preferably further may be less than or equal to 0.561.

[0635] The nvPM emission index ratio in depleted cruise may be greater than or equal to 0.448, preferably may be greater than or equal to 0.504 and preferably further may be greater than or equal to 0.56.

[0636] The nvPM emission index ratio in depleted cruise may be in the range of 0.448 to 0.673, preferably may be in the range of 0.504 to 0.617 and preferably further may be in the range of 0.560 to 0.561.

[0637] The nvPM emission index ratio in depleted cruise may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or in any range defined between any two of these values.

[0638] The depleted cruise nvPM emission index ratio of the gas turbine engine may be 0.446, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.677, or within any defined range between any two of these values.

[0639] A ratio of nvPM emissions index at idle-PMD can be defined as:

[0640] [Math.54] E^Imilsaf / EI jnaxTO SAp EI^mu-f / EI max TaFP

[0641] where:

[0642] Ê / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0643] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIaienti jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0644] Ê / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0645] Æ / maxTorT is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EIaienti Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0646] The NVPM-PMD emission index ratio of the gas turbine engine at idle may be less than 1.

[0647] The nvPM idle-PMD emission index ratio of the gas turbine engine may be greater than zero.

[0648] The nvPM-PMD emission index ratio may be less than or equal to 0.8 and preferably may be less than or equal to 0.6, again preferably may be less than or equal to 0.4 and again preferably may be less than or equal to 0.2.

[0649] The nvPM-PMD emission index ratio may be less than or equal to 0.178, preferably may be less than or equal to 0.164 and preferably further may be less than or equal to 0.149.

[0650] The nvPM-PMD emission index ratio may be greater than or equal to 0.118, preferably may be greater than or equal to 0.133 and preferably furthermore may be greater than or equal to 0.148.

[0651] The nvPM-PMD emission index ratio may be in the range of 0.118 to 0.178, preferably may be in the range of 0.133 to 0.164 and preferably further may be in the range of 0.148 to 0.149.

[0652] The nvPM idle-PMD emission index ratio may be less than 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1, or within any defined range between any two of these values.

[0653] The emission index ratio of nvPM at idle-PMD of the gas turbine engine may be 0.118, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, 0.17, 0.175, 0.178, or within any defined range between any two of these values.

[0654] A depleted cruise nvPM / PMD emission index ratio can be defined as:

[0655] [Math.55] croisièt ^aiipàtivriel. SAf / FI , -7-.--) Cd c * .t.UCtX L VyÙ / ll I niQX. TO FF

[0656] where:

[0657] E / cruise (impoverished e),saf can be defined as:

[0658] [Math.56] ^inaxTO, SV + montage, SAF 2

[0659] ^ / cruise (impoverished),ff can be defined as:

[0660] [Math.57] ^^inatTO, FFEl montée, FF 2

[0661] £ / maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0662] £7 rise, saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions to which it is calculated if fuel supplied to the plurality of fuel spray nozzles includes sustainable aviation fuel;

[0663] Ί / maxTOFF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which Σ7maxTo,sAF is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0664] £7mOntée ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which £7maxTo,sAF is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0665] The NVPM / PMD emission index ratio of the gas turbine engine in lean cruise may be less than 1.

[0666] The ratio of nvPM emissions index in depleted cruise / PMD may be greater than zero.

[0667] The ratio of the nvPM emissions index in depleted cruise / PMD may be less than or equal to 0.99 and preferably may be less than or equal to 0.98.

[0668] The ratio of the nvPM emissions index in depleted cruise / PMD may be less than or equal to 0.97, preferably may be less than or equal to 0.961, and preferably further may be less than or equal to 0.873.

[0669] The ratio of the nvPM emissions index in depleted cruise / PMD may be greater than or equal to 0.69, preferably may be greater than or equal to 0.776, and preferably furthermore may be greater than or equal to 0.863.

[0670] The nvPM emission index ratio in depleted cruise / PMD may be in the range of 0.690 to 0.970, preferably may be in the range of 0.776 to 0.961 and preferably further may be in the range of 0.863 to 0.873.

[0671] The ratio of the nvPM emissions index in depleted cruise / PMD may be less than or equal to 0.97, preferably may be less than or equal to 0.955, and preferably further may be less than or equal to 0.868.

[0672] The ratio of the nvPM emissions index in depleted cruise / PMD may be greater than or equal to 0.693, preferably may be greater than or equal to 0.78, and preferably furthermore may be greater than or equal to 0.867.

[0673] The nvPM emission index ratio in depleted cruise / PMD may be in the range of 0.693 to 0.970, preferably may be in the range of 0.780 to 0.955 and preferably further may be in the range of 0.867 to 0.868.

[0674] The ratio of the nvPM emissions index in depleted cruise / PMD may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or within any defined range between any two of these values.

[0675] The depleted cruise nvPM / PMD emission index ratio of the gas turbine engine 10 can be 0.69, 0.7, 0.725, 0.75, 0.775, 0.8, 0.825, 0.85, 0.875, 0.9, 0.925, 0.95, 0.97, 0.99, or within any defined range between any two of these values.

[0676] A low-speed nvPM emission index ratio can be defined as:

[0677] [Math.58] HraiauH SAf / EI Gnjjsj£rg(appa;n,r jg^^ El,cruise(appaiJvrie),FF

[0678] where:

[0679] Ê / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0680] ^ / cruise (impoverished) ,saf can be defined as:

[0681] [Math.59] ^^inàsTO, SAf+ EJ montée, SAP 2

[0682] £' / maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIaienti jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0683] Ê / montée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0684] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0685] E / cruise (impoverished) jF can be defined as:

[0686] [Math.60] O. ff+ ascent. FF 2

[0687] ÆZmaxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EIialenti ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0688] EImontée ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EIalenü ,Sai is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0689] The NVPM emission index ratio at idle / lean cruise of the gas turbine engine may be less than 1.

[0690] The nvPM emission index ratio at idle / lean cruise can be greater than zero.

[0691] The nvPM emission index ratio at idle / lean cruise may be less than or equal to 0.8, preferably may be less than or equal to 0.6, more preferably may be less than or equal to 0.4 and more preferably further may be less than or equal to 0.3.

[0692] The nvPM emission index ratio at idle / lean cruise may be less than or equal to 0.207, preferably may be less than or equal to 0.189 and preferably further may be less than or equal to 0.172.

[0693] The nvPM emission index ratio at idle / lean cruise may be greater than or equal to 0.135, preferably may be greater than or equal to 0.152 and preferably further may be greater than or equal to 0.169.

[0694] The nvPM emission index ratio at idle / lean cruise may be in the range of 0.135 to 0.207, preferably may be in the range of 0.152 to 0.189 and preferably further may be in the range of 0.169 to 0.172.

[0695] The nvPM emission index ratio at idle / lean cruise may be less than or equal to 0.206, preferably may be less than or equal to 0.189 and preferably further may be less than or equal to 0.171.

[0696] The nvPM emission index ratio at idle / lean cruise may be greater than or equal to 0.136, preferably may be greater than or equal to 0.153 and preferably further may be greater than or equal to 0.17.

[0697] The nvPM emission index ratio at idle / lean cruise may be in the range of 0.136 to 0.206, preferably may be in the range of 0.153 to 0.189 and preferably further may be in the range of 0.170 to 0.171.

[0698] The nvPM emission index ratio at idle / lean cruise may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any defined range between any two of these values.

[0699] The nvPM emission index ratio at idle / lean cruise can be 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, 0.17, 0.175, 0.18, 0.185, 0.19, 0.195, 0.2, 0.205, 0.207, or within any defined range between any two of these values.

[0700] A rich cruise nvPM emission index ratio can be defined as:

[0701] [Math.61] Z7 T 1 rich cruiser), SAF pi 1 cruise&iriche), FF

[0702] where:

[0703] E / cruise (rich), saf can be defined as:

[0704] [Math.62] The climb, SAF^~ The approach,. SAF 2

[0705] ^' / cruise (rich)^f can be defined as:

[0706] [Math.63] EJ ascent, Fp+ approach, FF 2

[0707] Elmontée >Saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0708] Ê / approach ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which EImontée ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0709] -EImontée jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EImontée ,Sai is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0710] E' / approach,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0711] The rich cruise nvPM emission index ratio of the gas turbine engine may be less than 1.

[0712] The nvPM emission index ratio in rich cruise can be greater than zero.

[0713] The rich cruise nvPM emission index ratio may be less than or equal to 0.8, preferably may be less than or equal to 0.6, again preferably may be less than or equal to 0.4.

[0714] The rich cruise nvPM emission index ratio may be less than or equal to 0.325, preferably may be less than or equal to 0.298 and preferably further may be less than or equal to 0.271.

[0715] The rich cruise nvPM emission index ratio may be greater than or equal to 0.18, preferably may be greater than or equal to 0.202 and preferably further may be greater than or equal to 0.225.

[0716] The rich cruise nvPM emission index ratio may be in the range of 0.180 to 0.325, preferably may be in the range of 0.202 to 0.298 and preferably further may be in the range of 0.225 to 0.271.

[0717] The rich cruise nvPM emission index ratio may be less than or equal to 0.287, preferably may be less than or equal to 0.263 and preferably further may be less than or equal to 0.239.

[0718] The rich cruise nvPM emission index ratio may be greater than or equal to 0.19, preferably may be greater than or equal to 0.214 and preferably further may be greater than or equal to 0.238.

[0719] The rich cruise nvPM emission index ratio may be in the range of 0.190 to 0.287, preferably may be in the range of 0.214 to 0.263 and preferably further may be in the range of 0.238 to 0.239.

[0720] The rich cruise nvPM emission index ratio of the gas turbine engine may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any defined range between any two of these values.

[0721] The rich cruise nvPM emission index ratio of the gas turbine engine may be 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.325 or within any defined range between any two of these values.

[0722] A rich cruise nvPM / PMD emission index ratio can be defined as:

[0723] [Math.64] EIçroisier&içItàiSAF / EI maxTO S AF E' croisar^SMlPF / El maxTO FF

[0724] where:

[0725] ^ / cruise (rich), saf can be defined as:

[0726] [Math.65] Elinontée, SAp+ ^Rapproche S AF 2

[0727] and ^ / cruise (rich)^f can be defined as:

[0728] [Math.66] ^R ascends,FF^" ^Brings closer,FF 2

[0729] and where:

[0730] EImontée saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0731] ^fapproche ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for the same operating conditions to which >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0732] £7montée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EImontée ,Sai is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0733] ​​Ê / approach ,ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which EImontée ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0734] £'7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0735] ÆZmaxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0736] The rich cruise nvPM / PMD emission index ratio of the gas turbine engine may be less than 1.

[0737] The rich cruise nvPM / PMD emission index ratio may be greater than zero.

[0738] The rich cruise nvPM / PMD emission index ratio may be less than or equal to 0.8, preferably may be less than or equal to 0.7, and even more preferably may be less than or equal to 0.6.

[0739] The rich cruise nvPM / PMD emission index ratio may be less than or equal to 0.503, preferably may be less than or equal to 0.461, and preferably further may be less than or equal to 0.419.

[0740] The rich cruise nvPM / PMD emission index ratio may be greater than or equal to 0.279, preferably may be greater than or equal to 0.313, and preferably further may be greater than or equal to 0.348.

[0741] The rich cruise nvPM / PMD emission index ratio may be in the range of 0.279 to 0.503, preferably may be in the range of 0.313 to 0.461 and preferably further may be in the range of 0.348 to 0.419.

[0742] The rich cruise nvPM / PMD emission index ratio may be less than or equal to 0.444, preferably may be less than or equal to 0.407, and preferably further may be less than or equal to 0.37.

[0743] The rich cruise nvPM / PMD emission index ratio may be greater than or equal to 0.295, preferably may be greater than or equal to 0.332, and preferably furthermore may be greater than or equal to 0.369.

[0744] The rich cruise nvPM / PMD emission index ratio may be in the range of 0.295 to 0.444, preferably may be in the range of 0.332 to 0.407 and preferably furthermore may be in the range of 0.369 to 0.370.

[0745] The rich cruise nvPM / PMD emission index ratio of the gas turbine engine may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any defined range between any two of these values.

[0746] The rich cruise nvPM / PMD emission index ratio of the gas turbine engine may be 0.279, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.503, or within any defined range between any two of these values.

[0747] A rich idle / cruise nvPM emission index ratio can be defined as:

[0748] [Math.67] croisièrelj-Kh^SAF Elcalent^Ff / EI crojsjèr^rjc^

[0749] where:

[0750] Ê / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel (SAF);

[0751] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0752] EIaoisièie (rich)>Saf can be defined as:

[0753] [Math.68] EJ ascending, SAf^ EI approaching. SAF 2

[0754] E / cruise (rich),ff can be defined as:

[0755] [Math.69] EJ ascending, FF*" EJ approaching, FF -

[0756] f / climb,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIaienü Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0757] f / ascent ,ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIaienü Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0758] The approach, ,saf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which £7raiti ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0759] E / approach,ff is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 30% of the available thrust under the same operating conditions at which £7raienti ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0760] The NvPM emission index ratio at idle / rich cruise of the gas turbine engine may be less than 1.

[0761] The nvPM emission index ratio at idle / rich cruise can be greater than zero.

[0762] The nvPM emission index ratio at idle / lean cruise may be less than or equal to 0.9 and preferably may be less than or equal to 0.8 and preferably further may be less than or equal to 0.7.

[0763] The nvPM emission index ratio at idle / rich cruise may be less than or equal to 0.511, preferably may be less than or equal to 0.468 and preferably further may be less than or equal to 0.426.

[0764] The nvPM emission index ratio at idle / rich cruise may be greater than or equal to 0.283, preferably may be greater than or equal to 0.319 and preferably further may be greater than or equal to 0.354.

[0765] The nvPM emission index ratio at idle / rich cruise may be in the range of 0.283 to 0.511, preferably may be in the range of 0.319 to 0.468 and preferably further may be in the range of 0.354 to 0.426.

[0766] The nvPM emission index ratio at idle / rich cruise may be less than or equal to 0.482, preferably may be less than or equal to 0.442 and preferably further may be less than or equal to 0.402.

[0767] The nvPM emission index ratio at idle / rich cruise may be greater than or equal to 0.321, preferably may be greater than or equal to 0.361 and preferably further may be greater than or equal to 0.401.

[0768] The nvPM emission index ratio at idle / rich cruise can be in the range of 0.321 to 0.482, preferably can be in the range of 0.361 to 0.442 and preferably further can be in the range of 0.401 to 0.402.

[0769] The nvPM emission index ratio at idle / rich cruise of the gas turbine engine may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any defined range between any two of these values.

[0770] The nvPM emission index ratio at idle / rich cruise of the gas turbine engine may be 0.283, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.511, or within any defined range between any two of these values.

[0771] According to a thirty-sixth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0772] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0773] A ratio of nvPM emissions index at idle-PMD can be defined as:

[0774] [Math.70] rI slow AAf / El j^q^TO.SAF BlF^Mi,FF / EI mHxTOpF

[0775] where:

[0776] Ê / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0777] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIaienti jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0778] Δ / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which ΔIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0779] £7maxTojF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for the same operating conditions at which EIialenti ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0780] the ratio of the nvPM at idle to PMD emission index of the gas turbine engine is less than 1; and

[0781] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0782] The nvPM idle-PMD emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[0783] According to a thirty-seventh aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0784] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the device combustor can operate under a condition in which each of the fuel spray nozzles in the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles in the second subset of fuel spray nozzles, in which a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6;

[0785] in which:

[0786] A depleted cruise nvPM / PMD emission index ratio can be defined as:

[0787] [Math.71] £?ci:c>isièEe(âppw PJ^'TOFF

[0788] where:

[0789] E / cruise (impoverished), SAF can be defined as:

[0790] [Math.72] ^maxTO, SAF+ Elmontée, SAP 2

[0791] £ZcroiSière (impoverished) can be defined as:

[0792] [Math.73] ElmaxTO, / 7 + El montée, FF

[0793] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0794] EImontée saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which £7maXTo,sAF is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0795] £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which £7maxTo,sAF is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0796] Elmontée jj is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which £7maXTo,sAF is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0797] the ratio of the nvPM emissions index in lean cruise / PMD of the gas turbine engine is less than 1; and

[0798] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0799] The ratio of nvPM emissions index in depleted cruise / PMD can be as defined above in relation to the thirty-fifth aspect.

[0800] According to a thirty-eighth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0801] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0802] A ratio of the nvPM emission index at idle / lean cruise can be defined as:

[0803] [Math.74] iAp / ai cro:sèr^appaiivp^ BlffimuFr / EI crosjère(appa wrieXTE

[0804] where:

[0805] Æ' / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0806] ^ / cruise (impoverished),saf can be defined as:

[0807] [Math.75] ^inaxTO, SV + montage, SAF 2

[0808] ^7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIaienti jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0809] £7montée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions to which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0810] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0811] E / cruise (impoverished) jF can be defined as:

[0812] [Math.76] ElmaxTO, Elmontée, FF 2

[0813] Ί / maxTOFF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EIialenti ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0814] Ê / montée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIràleaü Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0815] the nvPM emission index ratio at idle / lean cruise of the gas turbine engine is less than 1; and

[0816] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0817] The nvPM emission index ratio at idle / lean cruise can be as defined above in relation to the thirty-fifth aspect.

[0818] According to a thirty-ninth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0819] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0820] A rich cruise nvPM emission index ratio can be defined as:

[0821] [Math.77] E Froisière (rich), SAP PJ cruiseririche), FF

[0822] where:

[0823] E / cruise (rich), saf can be defined as:

[0824] [Math.78] The climb, EI approaches, SAP 2

[0825] ^' / cruise (rich)^f can be defined as:

[0826] [Math.79] EImontée, PP^ EI&ppræhe, FF 2

[0827] EImontée saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0828] £7appropOche ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which EImontée jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0829] Elmontée jj is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EImontée jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0830] ^ / approach jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which EImontée jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0831] the rich cruise nvPM emission index ratio of the gas turbine engine is less than 1; and

[0832] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0833] The rich cruise nvPM emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[0834] According to a fortieth aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0835] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0836] A rich cruise nvPM / PMD emission index ratio can be defined as:

[0837] [Math. 80]

[0838] where:

[0839] ^ / cruise (rich), saf can be defined as:

[0840] [Math.81] The climb, ^^approach, SAP 2

[0841] and E / cruise (rich),ff can be defined as:

[0842] [Math. 82] The climb. FF^ ^approach. FF 2

[0843] and where:

[0844] f / climb,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0845] E / approach, saf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0846] f / climb,ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIclimb >Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0847] E / approach,ff is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 30% of the available thrust for the same operating conditions to which EImontée >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0848] f / maxTo.sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0849] f / maxiorF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0850] the rich cruise nvPM / PMD emission index ratio of the gas turbine engine is less than 1; and

[0851] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0852] The rich cruise nvPM / PMD emission index ratio may be as defined above in relation to the thirty-fifth aspect.

[0853] According to a forty-first aspect, a gas turbine engine for an aircraft is provided, comprising any of the following features:

[0854] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0855] A rich idle / cruise nvPM emission index ratio can be defined as:

[0856] [Math.83] cro^

[0857] where:

[0858] Æ' / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel (SAF);

[0859] Æ' / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0860] ^ / cruise (rich), saf can be defined as:

[0861] [Math. 84] The climb, SAF^^approach, SAP 2

[0862] E / cruise (rich),ff can be defined as:

[0863] [Math.85] El climb,PP^ EIapprOahe. PP 2

[0864] E / climb,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions to which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0865] E / ascent ,ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIràleaü Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0866] EZapproche saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EIràleaü Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0867] E / FF approach is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which E / raiti ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0868] the nvPM emission index ratio at idle / rich cruise of the gas turbine engine is less than 1; and

[0869] The gas turbine engine is designed to supply fuel including sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0870] The nvPM emission index ratio at idle / rich cruise can be as defined above in relation to the thirty-fifth aspect.

[0871] According to a forty-second aspect, a method of operating the gas turbine engine of any one or more of the thirty-fifth, thirty-sixth, thirty-seventh, thirty-eighth, thirty-ninth, fortieth or forty-and- The first aspect is provided, the process including supplying fuel including sustainable aviation fuel to the plurality of fuel spray nozzles.

[0872] According to a forty-third aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0873] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6;

[0874] in which:

[0875] A depleted cruise nvPM emission index ratio can be defined as:

[0876] [Math. 86] FI ( \ * cruise^impoverished), SAF Tpr " impoverished cruise FF

[0877] where:

[0878] E / cruise (impoverished), SAF can be defined as:

[0879] [Math. 87] ElmaxTO. Elmontée; SAF 2

[0880] ^ / cruise (impoverished) can be defined as:

[0881] [Math.88] ElmaxTO. Fp+ Elmontée, FF

[0882] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0883] EImontée saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for the given operating conditions if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0884] £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[0885] S / ascent jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0886] the nvPM emission index ratio in depleted cruise is less than 1; and

[0887] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0888] The nvPM emission index ratio in depleted cruise can be as defined above in relation to the thirty-fifth aspect.

[0889] A ratio of nvPM emissions index at idle-PMD can be defined as:

[0890] [Math. 89] slow motion saf / EI-jQ^p EI™i<»w / EI msxTO,FF

[0891] where:

[0892] ÊLaienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0893] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIaienti Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0894] EIialenti FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0895] £ / maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EIaienti Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0896] The NVPM-PMD emission index ratio of the gas turbine engine may be less than 1.

[0897] The nvPM idle-PMD emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[0898] A depleted cruise nvPM / PMD emission index ratio can be defined as:

[0899] [Math.90] SAf / EI BlaxTO.SAF ^pfaim iétFF / EI Q pp

[0900] where:

[0901] E / cruise (impoverished), SAF can be defined as:

[0902] [Math.91] EEuc^TO, SAf+ EEnoity, SAF 2

[0903] E / cruise (impoverished),ff can be defined as:

[0904] [Math.92] EEnaxTO. FF^ ■E'Lnoj.itée, FF 2

[0905] Æ' / maxTo.sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0906] EImontée saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which £7maXTo,sAF is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0907] £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which £7maxTo,sAF is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0908] Elmontée jj is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which £7maXTo,sAF is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0909] The NVPM / PMD emission index ratio of the gas turbine engine in lean cruise may be less than 1.

[0910] The ratio of nvPM emissions index in depleted cruise / PMD can be as defined above in relation to the thirty-fifth aspect.

[0911] A low-speed nvPM emission index ratio can be defined as:

[0912] [Math.93] Eirthnu, SAf / EJ crojsfêre(appail¥rie),SAF EJrsientj.Fp / EI cropigre[appauvr jejpp

[0913] where:

[0914] ^ / idle,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0915] ^ / cruise (impoverished) ,saf can be defined as:

[0916] [Math.94] ElniaxTO, SzlfL SAF 2

[0917] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIaienti jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0918] EImontée saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0919] Æ' / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0920] ^ / cruise (impoverished) jf can be defined as:

[0921] [Math.95] ElmàxTO, FF^ Elmontée, FF 2

[0922] Æ'ZmaxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EIialenti ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0923] EImontée jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EIaienü Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0924] The NVPM emission index ratio at idle / lean cruise of the gas turbine engine may be less than 1.

[0925] The nvPM emission index ratio at idle / lean cruise can be as defined above in relation to the thirty-fifth aspect.

[0926] A rich cruise nvPM emission index ratio can be defined as:

[0927] [Math.96] cruise^rich), SAF 2 cruise(riFh^^ FF

[0928] where:

[0929] E / cruise (rich), saf can be defined as:

[0930] [Math.97] The climb, SAF^~ The approach, SAF 2

[0931] EIaoisiiie (rich)>FF can be defined as:

[0932] [Math.98] El climb, FF-*- EIapppochprpp 2

[0933] EImontée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0934] Ê / approach ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which EImontée jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0935] £7montée jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EImontée jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0936] E' / approach,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EImontée,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and in which

[0937] The rich cruise nvPM emission index ratio of the gas turbine engine may be less than 1.

[0938] The rich cruise nvPM emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[0939] A rich cruise nvPM / PMD emission index ratio can be defined as:

[0940] [Math.99] EhromèrdrickalSAF / Ei n}axT i:roisiè.£Ef cg ' IiiaX J '-',rr

[0941] where:

[0942] E / cruise (rich), saf can be defined as:

[0943] [Math. 100] EJ rise, SAF^~ EJ approach, SAP 2

[0944] and E' / cruise (rich) jf can be defined as:

[0945] [Math. 101] EJmontée, Fp+ EJapproche, PF

[0946] and where:

[0947] EImontée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or under other different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel;

[0948] £7 approach,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust under the same operating conditions to which EImontée jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0949] £7montée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EImontée jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0950] E' / approach ,ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions at which EImontée ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0951] E7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0952] E / maxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0953] The rich cruise nvPM / PMD emission index ratio of the gas turbine engine may be less than 1.

[0954] The rich cruise nvPM / PMD emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[0955] A rich idle / cruise nvPM emission index ratio can be defined as:

[0956] [Math. 102] Hmw / E! craisjér^riche}SAP Ei^^».FF / EI crosFèr^Fii:bejpp

[0957] where:

[0958] E' / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of the available thrust for the given operating conditions, or under other conditions different operating modes, if a fuel supplied to the plurality of fuel spray nozzles includes a sustainable aviation fuel (SAF);

[0959] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0960] ^ / cruise (rich), saf can be defined as:

[0961] [Math. 103] Elnlaotée, SAF^ P ^approach,. SAF 2

[0962] EIaoisièie (rich)>FF can be defined as:

[0963] [Math. 104] Elmontée, FF^~ El approche, FF 2

[0964] Ê / montée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which EIràleaü jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0965] Ê / montée ,ff is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which EIràleaü Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0966] ^ / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EIràleaü Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[0967] ^ / approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EIalenü ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0968] The NvPM emission index ratio at idle / rich cruise of the gas turbine engine may be less than 1.

[0969] The nvPM emission index ratio at idle / rich cruise can be as defined above in relation to the thirty-fifth aspect.

[0970] According to a forty-fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0971] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0972] an nvPM-PMD emission index ratio can be defined as:

[0973] [Math. 105] EIralé„il SAF / EI inax TO &^ Eh^uFF / EI Uax TO pp

[0974] where:

[0975] Æ' / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0976] £7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0977] Ê / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same operating conditions at which ELaiemi ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0978] £7maxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of thrust available for the same operating conditions under which EIalenti >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0979] the ratio of the nvPM at idle to PMD emission index of the gas turbine engine is less than 1; and

[0980] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0981] The nvPM idle-PMD emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[0982] According to a forty-fifth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0983] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[0984] A depleted cruise nvPM / PMD emission index ratio can be defined as:

[0985] [Math. 106] ^1oroisïérdafipauYrïd SAF axT0 FF

[0986] where:

[0987] EZcroisière (impoverished),saf can be defined as:

[0988] [Math. 107] ElmaxTO, EIinClntée, SAF 2

[0989] ^ / cruise (impoverished) can be defined as:

[0990] [Math. 108] ElInaxTO, FF^ Elmontée, FF 2

[0991] £ / maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[0992] £7 rise, saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions to which is calculated if fuel supplied to the plurality of fuel spray nozzles includes sustainable aviation fuel;

[0993] £7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which £7maxTo,sAF is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[0994] Ê / montée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which £7maxTo,sAF is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[0995] the ratio of the nvPM emissions index in lean cruise / PMD of the gas turbine engine is less than 1; and

[0996] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[0997] The ratio of the nvPM emissions index in depleted cruise / PMD can be as defined above in relation to the thirty-fifth aspect.

[0998] According to a forty-sixth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[0999] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of nozzles. fuel spraying, wherein the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; where:

[1000] A ratio of the nvPM emission index at idle / lean cruise can be defined as:

[1001] [Math. 109] SAF / EI Cruise{impoverished\SAF EI'«FntlFF / EI çroisièftJ^ppà Uvrie],FF

[1002] where:

[1003] Æ' / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1004] Elcroisière (impoverished), saf can be defined as:

[1005] [Math. 110] ElmaxTO, SAf+ El}nc,ntpe gAF 2

[1006] £7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EIialenti jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1007] EImontée saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which EIràleaü Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1008] Æ' / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIalenü >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1009] E / cruise (impoverished) jf can be defined as:

[1010] [Math. 111] ElmaxTO, FEE El montée, FF 2

[1011] ÆZmaxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of thrust available under the same operating conditions under which EIialeDÜ >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[1012] £7montée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIalenü >Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1013] the nvPM emission index ratio at idle / lean cruise of the gas turbine engine is less than 1; and

[1014] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1015] The nvPM emission index ratio at idle / lean cruise can be as defined above in relation to the thirty-fifth aspect.

[1016] According to a forty-seventh aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1017] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[1018] A rich cruise nvPM emission index ratio can be defined as:

[1019] [Math. 112] FT . .. , . , . 1 cruise ship (ricrie), SAF FJ 1 cruise (rich\ FF)

[1020] where:

[1021] EIaoisièie (rich) > Saf can be defined as:

[1022] [Math. 113] EEnonteé, EIapproche, SAF 2

[1023] ^ / cruise (rich),ff can be defined as:

[1024] [Math. 114] The climb, FF-*" ^7 approach, FF

[1025] Ê / climb ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1026] ^ / approach ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions to which EImontée >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1027] Ί / climb,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which Ί / climb >Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[1028] ^ / approach ,ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust under the same operating conditions to which EImontée >Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1029] the rich cruise nvPM emission index ratio of the gas turbine engine is less than 1; and

[1030] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1031] The rich cruise nvPM emission index ratio can be as defined above in relation to the thirty-fifth aspect.

[1032] According to a forty-eighth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1033] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of spray nozzles fuel is supplied with fuel at a higher fuel flow rate to each of the fuel spray nozzles in the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; where:

[1034] A rich cruise nvPM / PMD emission index ratio can be defined as:

[1035] [Math. 115] El mount AwkélSAr / FI maxT O.SAF Elcroteièreÿich&Fp / EI m^xTO FF

[1036] where:

[1037] EZcroisière (rich), saf can be defined as:

[1038] [Math. 116] Ascent, SAP^approach, SAP 2

[1039] and E / cruise (rich jjf can be defined as:

[1040] [Math. 117] The climb, Fp+ The approach, FF 2

[1041] and where:

[1042] EImontée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1043] ^fapproach ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same operating conditions to which EImontée ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1044] £7mOntée jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EImontée Saf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1045] ^ / approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1046] £' / maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée jSaf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[1047] £7maxTo,FF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EImontée Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1048] the rich cruise nvPM / PMD emission index ratio of the gas turbine engine is less than 1; and

[1049] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1050] The rich cruise nvPM / PMD emission index ratio may be as defined above in relation to the thirty-fifth aspect.

[1051] According to a forty-ninth aspect, a method of operating a gas turbine engine is provided, the gas turbine engine comprising:

[1052] a combustor device, comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber, in which the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, in which the combustor device can operate under a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles,in which the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6; in which: ,

[1053] A ratio of the nvPM emission index at idle / rich cruise can be defined as:

[1054] [Math. 118] BIra,™tiSA^EE;rots^^^ BInlm Wf / E! cruise^rich)>pp

[1055] where:

[1056] Ê / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for given operating conditions and if a fuel supplied to the plurality of fuel spray nozzles includes sustainable aviation fuel (SAF);

[1057] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same operating conditions at which EIalenü ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1058] ^ / cruise (rich), saf can be defined as:

[1059] [Math. 119] Flapproche, SAP 2

[1060] E / cruise (rich)jf can be defined as:

[1061] [Math. 120] The climb, FF^~ approaches, FF' 2

[1062] Ê / montée ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same operating conditions at which EIalenü ,Sai is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel;

[1063] EImontée ff is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same operating conditions at which EIalenü ,Sai is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1064] ^ / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EIràleaü Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[1065] ^ / approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EIràleaü Saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1066] the nvPM emission index ratio at idle / rich cruise of the gas turbine engine is less than 1; and

[1067] The method includes supplying fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1068] The ratio of the nvPM emission index at idle / rich cruise can be as defined above in relation to the thirty-fifth aspect.

[1069] The following statements may apply to any one of the first through the forty-ninth aspects:

[1070] The ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles may be in the range of 1:4 to 1:5.

[1071] The ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles may be in the range of 1:4.25 to 1:4.75.

[1072] The first subset of fuel spray nozzles may include between 1 and 10 fuel spray nozzles.

[1073] The first subset of fuel spray nozzles may include between 3 and 5 fuel spray nozzles.

[1074] The second subset of fuel spray nozzles may include between 10 and 25 fuel spray nozzles.

[1075] The second subset of fuel spray nozzles may include between 14 and 22 fuel spray nozzles.

[1076] The second subset of fuel spray nozzles may include between 16 and 20 fuel spray nozzles.

[1077] The combustor device may include the igniter(s).

[1078] Each of the first subset of fuel spray nozzles can be located closer to the respective igniter(s) than the second subset.

[1079] One or more of the igniters may be arranged diametrically opposite another one or more of the igniters.

[1080] The fuel supplied to the plurality of fuel spray nozzles may include a % of SAF in the range of 50% and 100%.

[1081] The fuel supplied to the plurality of fuel spray nozzles may include a % of SAF in the range of 70% and 100%.

[1082] The fuel supplied to the plurality of fuel spray nozzles may include a % of S AF in the range of 90% and 100%.

[1083] According to one fiftieth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1084] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber;

[1085] in which:

[1086] A first nvPM emission index ratio at idle-PMD can be defined as:

[1087] [Math. 121] slowed down FI May 1st TO

[1088] where:

[1089] Δ / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[1090] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 100% of the available thrust for the given operating conditions;

[1091] the first ratio of the nvPM emission index at idle to PMD of the gas turbine engine is less than 2; and

[1092] The gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1093] The first NvPM-PMD emission index ratio of the gas turbine engine may be greater than zero.

[1094] The first nvPM-PMD emission index ratio may be less than 1.26 and preferably may be less than 1.16 and more preferably may be less than 1.05.

[1095] The first nvPM-PMD emission index ratio at idle may be less than 1.15 and preferably may be less than 1.05 and more preferably may be less than 0.951.

[1096] The first nvPM-PMD emission index ratio at idle may be less than 0.96 and preferably may be less than 0.88 and more preferably may be less than 0.8.

[1097] The first nvPM-PMD emission index ratio may be less than 0.791 and preferably may be less than 0.725 and more preferably may be less than 0.659.

[1098] The first nvPM-PMD emission index ratio may be less than 0.415 and preferably may be less than 0.381 and more preferably may be less than 0.346.

[1099] The first nvPM-PMD emission index ratio at idle may be less than 1.5 and preferably may be less than 1 and more preferably may be less than 0.5.

[1100] The first nvPM-PMD emission index ratio may be less than or equal to 0.187 and preferably may be less than or equal to 0.171 and more preferably may be less than or equal to 0.156.

[1101] The first nvPM-PMD emission index ratio may be less than or equal to 0.143 and preferably may be less than or equal to 0.131 and more preferably may be less than or equal to 0.119.

[1102] The first nvPM-PMD emission index ratio may be less than or equal to 0.170 and preferably may be less than or equal to 0.156 and more preferably may be less than or equal to 0.142.

[1103] The first nvPM-PMD emission index ratio may be less than or equal to 0.0615 and preferably may be less than or equal to 0.0564 and more preferably may be less than or equal to 0.0513.

[1104] The first nvPM-PMD emission index ratio may be less than or equal to 0.118 and preferably may be less than or equal to 0.108 and more preferably may be less than or equal to 0.0978.

[1105] The first nvPM-PMD emission index ratio may be greater than or equal to 0.0409 and preferably may be greater than or equal to 0.0461 and more preferably may be greater than or equal to 0.0512.

[1106] The first nvPM-PMD emission index ratio may be greater than or equal to 0.0956 and preferably may be greater than or equal to 0.107 and more preferably may be greater than or equal to 0.119.

[1107] The first nvPM-PMD emission index ratio may be greater than or equal to 0.0509 and preferably may be greater than or equal to 0.0573 and more preferably may be greater than or equal to 0.0636.

[1108] The first nvPM-PMD emission index ratio may be greater than or equal to 0.124 and preferably may be greater than or equal to 0.139 and more preferably may be greater than or equal to 0.155.

[1109] The first nvPM-PMD emission index ratio may be greater than or equal to 0.0524 and preferably may be greater than or equal to 0.059 and more preferably may be greater than or equal to 0.0656.

[1110] The first nvPM-PMD emission index ratio may be in the range of 0.0409 to 0.187 and preferably may be in the range of 0.0461 to 0.171 and, more preferably, may be in the range of 0.0512 to 0.156.

[1111] The first nvPM-PMD emission index ratio may be in the range of 0.0956 to 0.187 and preferably may be in the range of 0.107 to 0.171 and, more preferably, may be in the range of 0.119 to 0.156.

[1112] The first nvPM-PMD emission index ratio may be in the range of 0.0509 to 0.143 and preferably may be in the range of 0.0573 to 0.131 and, more preferably, may be in the range of 0.0636 to 0.119.

[1113] The first nvPM-PMD emission index ratio may be in the range of 0.0956 to 0.17 and preferably may be in the range of 0.107 to 0.156 and, more preferably, may be in the range of 0.119 to 0.142.

[1114] The first nvPM-PMD emission index ratio may be in the range of 0.124 to 0.187 and preferably may be in the range of 0.139 to 0.171 and, more preferably, may be in the range of 0.155 to 0.156.

[1115] The first nvPM-PMD emission index ratio may be in the range of 0.0409 to 0.0615 and preferably may be in the range of 0.0461 to 0.0564 and, more preferably, may be in the range of 0.0512 to 0.0513.

[1116] The first nvPM-PMD emission index ratio may be in the range of 0.0524 to 0.118 and preferably may be in the range of 0.059 to 0.108 and, more preferably, may be in the range of 0.0656 to 0.0978.

[1117] The first nvPM idling-PMD emission index ratio may be less than 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or within any defined range between any two of these values.

[1118] A second nvPM-PMD emission index ratio can be defined as:

[1119] [Math. 122]

[1120] where:

[1121] ÊLaienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for the given operating conditions, or for operating conditions different data, and whether a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1122] £' / maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which £7raiti ,saf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1123] Ê / raienti jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for the same given operating conditions at which EIràleaü jSaf is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1124] £7maxTo,FF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1125] and in which the second ratio of the nvPM idle-PMD emission index of the gas turbine engine may be less than 1.

[1126] The second ratio of the nvPM idle-PMD emission index of the gas turbine engine may be greater than zero.

[1127] The second nvPM-PMD emission index ratio may be less than or equal to 0.8 and preferably may be less than or equal to 0.6 and more preferably may be less than or equal to 0.4.

[1128] The second nvPM-PMD emission index ratio may be less than or equal to 0.178 and preferably may be less than or equal to 0.164 and more preferably may be less than or equal to 0.149.

[1129] The second nvPM-PMD emission index ratio may be greater than or equal to 0.03 and preferably may be greater than or equal to 0.06 and more preferably may be greater than or equal to 0.09.

[1130] The second nvPM-PMD emission index ratio may be greater than or equal to 0.118 and preferably may be greater than or equal to 0.133 and more preferably may be greater than or equal to 0.148.

[1131] The second nvPM-PMD emission index ratio may be in the range of 0.118 to 0.178 and preferably may be in the range of 0.133 to 0.164 and more preferably may be in the range of 0.148 to 0.149.

[1132] The second nvPM-PMD emission index ratio may be less than 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1, or within any defined range between any two of these values.

[1133] According to a fifty-first aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1134] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1135] A second nvPM-PMD emission index ratio can be defined as:

[1136] [Math. 123] FF / Elmxsnl l,p

[1137] where:

[1138] Ê / raienti ,saf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for given operating conditions and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1139] £'7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which EIialeaü jSaf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1140] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for the same given operating conditions at which EIalenü ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1141] ^fmaxTojr is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1142] the second ratio of the nvPM idle-PMD emission index of the gas turbine engine is less than 1; and

[1143] The gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1144] The second nvPM idling-PMD emission index ratio defined in the fifty-first aspect may be as defined above in relation to the fiftieth aspect.

[1145] According to a fifty-second aspect, a method of operating the gas turbine engine of the fiftieth aspect or of the fifty-first aspect is provided, the method comprising supplying fuel comprising a durable aviation fuel to the plurality of fuel spray nozzles.

[1146] According to a fifty-third aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1147] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1148] A first nvPM emission index ratio at idle-PMD can be defined as:

[1149] [Math. 124] slow motion ^maxTO

[1150] where:

[1151] Δ / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[1152] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 100% of the available thrust for the given operating conditions;

[1153] the first ratio of the nvPM emission index at idle to PMD of the gas turbine engine is less than 2; and

[1154] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1155] The first nvPM idling-PMD emission index ratio can be as defined above in relation to the fiftieth aspect.

[1156] A second nvPM-PMD emission index ratio can be defined as:

[1157] [Math. 125]

[1158] where:

[1159] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for given operating conditions, or for different given operating conditions, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1160] £' / maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1161] Ê / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for the same given operating conditions at which EIalenü ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1162] £7maxTojF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 100% of available thrust under the same given operating conditions at which EIialeaü jSaf is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel; and

[1163] in which the second ratio of the nvPM idle-PMD emission index of the gas turbine engine may be less than 1.

[1164] The second nvPM idling-PMD emission index ratio can be as defined above in relation to the fiftieth aspect.

[1165] According to a fifty-fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1166] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1167] A second nvPM-PMD emission index ratio can be defined as:

[1168] [Math. 126] Ehalent,, SAf / Elma!cfo, SAF EI™1^ FF / EIm^TQ e!,

[1169] where:

[1170] Æ' / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for given operating conditions and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1171] ^7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which £7raiti ,saf is calculated, and if a fuel supplied to the combustor device includes a sustainable aviation fuel;

[1172] Ê / raienti jf is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for the same given operating conditions at which EIràleaü jSaf is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1173] £7maxTo,FF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 100% of available thrust for the same given operating conditions at which EIiaienti ,Sai is calculated, and if a fuel supplied to the combustor device is a fossil-based hydrocarbon fuel;

[1174] the second ratio of the nvPM idle-PMD emission index of the gas turbine engine is less than 1; and

[1175] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1176] The second nvPM idling-PMD emission index ratio can be as defined above in relation to the fiftieth aspect.

[1177] According to a fifty-fifth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1178] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1179] A fuel flow rate nvPM emission index ratio can be defined as:

[1180] [Math. 127] El raiti^^f.slow down ElmaxTO* f. maxTO

[1181] where:

[1182] Ί / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for given operating conditions;

[1183] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 100% of the available thrust for the given operating conditions;

[1184] Wf idle is the fuel flow to the fuel spray nozzles in kg / s at approximately 7% of the thrust available for the given operating conditions; and

[1185] IVfjnaxTO is the fuel flow rate to the fuel spray nozzles in kg / s at approximately 100% of the thrust available for the given operating conditions;

[1186] the nvPM emission index ratio of the gas turbine engine fuel flow rate is less than 0.2; and

[1187] The gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1188] The nvPM emission index ratio of the fuel flow may be less than 0.13 and preferably may be less than 0.119 and more preferably may be less than 0.108.

[1189] The nvPM emission index ratio of the fuel flow may be less than 0.091 and preferably may be less than 0.0834 and more preferably may be less than 0.0758.

[1190] The nvPM emission index ratio of the fuel flow may be less than 0.123 and preferably may be less than 0.113 and more preferably may be less than 0.103.

[1191] The nvPM emission index ratio of the fuel flow may be less than 0.0819 and preferably may be less than 0.075 and more preferably may be less than 0.0682.

[1192] The nvPM emission index ratio of the fuel flow may be less than 0.0357 and preferably may be less than 0.0327 and more preferably may be less than 0.0298.

[1193] The nvPM emission index ratio of the fuel flow may be less than 0.17 and preferably may be less than 0.15 and more preferably may be less than 0.12.

[1194] The ratio of the nvPM emission index of the fuel flow rate may be less than or equal to 0.0193 and preferably less than or equal to 0.0177 and more preferably less than or equal to 0.0161.

[1195] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.0135 and preferably may be less than or equal to 0.0124 and more preferably may be less than or equal to 0.0113.

[1196] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.0182 and preferably may be less than or equal to 0.0167 and more preferably may be less than or equal to 0.0152.

[1197] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.00529 and preferably may be less than or equal to 0.00485 and more preferably may be less than or equal to 0.00441.

[1198] The nvPM emission index ratio of the fuel flow may be less than or equal to 0.0122 and preferably may be less than or equal to 0.0112 and more preferably may be less than or equal to 0.0102.

[1199] The ratio of the nvPM emission index of the fuel flow rate may be greater than or equal to 0.00352 and preferably may be greater than or equal to 0.00396 and more preferably may be less than or equal to 0.0044.

[1200] The ratio of the nvPM emission index of the fuel flow rate may be greater than or equal to 0.0107 and preferably may be greater than or equal to 0.012 and more preferably may be less than or equal to 0.0133.

[1201] The ratio of the nvPM emission index of the fuel flow rate may be greater than or equal to 0.00561 and preferably may be greater than or equal to 0.00631 and more preferably may be less than or equal to 0.00701.

[1202] The ratio of the nvPM emission index of the fuel flow rate may be greater than or equal to 0.0128 and preferably may be greater than or equal to 0.0144 and more preferably may be less than or equal to 0.016.

[1203] The ratio of the nvPM emission index of the fuel flow rate may be greater than or equal to 0.00564 and preferably may be greater than or equal to 0.00635 and more preferably may be less than or equal to 0.00705.

[1204] The ratio of the nvPM emission index of the fuel flow may be in the range of 0.00352 to 0.0193 and preferably in the range of 0.00396 to 0.0177 and more preferably in the range of 0.00440 to 0.0161.

[1205] The ratio of the nvPM emission index of the fuel flow rate may be in the range of 0.0107 to 0.0193 and preferably in the range of 0.0120 to 0.0177 and more preferably in the range of 0.0133 to 0.0161.

[1206] The ratio of the nvPM emission index of the fuel flow rate may be in the range of 0.00561 to 0.0135 and preferably in the range of 0.00631 to 0.0124 and more preferably in the range of 0.00701 to 0.0113.

[1207] The ratio of the nvPM emission index of the fuel flow rate may be in the range of 0.0107 to 0.0182 and preferably in the range of 0.0120 to 0.0167 and more preferably in the range of 0.0133 to 0.0152.

[1208] The ratio of the nvPM emission index of the fuel flow rate may be in the range of 0.0128 to 0.0193 and preferably in the range of 0.0144 to 0.0177 and more preferably in the range of 0.0160 to 0.0161.

[1209] The ratio of the nvPM emission index of the fuel flow may be in the range of 0.00352 to 0.00529 and preferably in the range of 0.00396 to 0.00485 and more preferably in the range of 0.00440 to 0.00441.

[1210] The ratio of the nvPM emission index of the fuel flow rate may be in the range of 0.00564 to 0.0122 and preferably in the range of 0.00635 to 0.0112 and more preferably in the range of 0.00705 to 0.0102.

[1211] The nvPM emission index ratio of the fuel flow may be less than 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or in any range defined between any two of these values.

[1212] IVfralient in kg / s can be in the range of 0.185 to 0.362 and preferably can be in the range of 0.209 to 0.331 and more preferably in the range of 0.232 to 0.301.

[1213] Wfiaient! in ^g / s can be in the range of 0.215 to 0.362, preferably can be in the range of 0.242 to 0.331 and more preferably can be in the range of 0.269 to 0.301.

[1214] IVf idle in kg / s can be in the range of 0.215 to 0.349, preferably can be in the range of 0.242 to 0.320 and more preferably can be in the range of 0.269 to 0.291.

[1215] IVfrentien kg / s can be in the range of 0.185 to 0.324 and preferably can be in the range of 0.209 to 0.297 and more preferably in the range of 0.232 to 0.270.

[1216] IVfralient in ^g / s can be in the range of 0.215 to 0.336, preferably can be in the range of 0.242 to 0.308 and more preferably can be in the range of 0.269 to 0.280.

[1217] IVfralenti in ^g / s can be in the range of 0.232 to 0.349, preferably can be in the range of 0.261 to 0.320 and more preferably can be in the range of 0.290 to 0.291.

[1218] IVf idle in kg / s can be in the range of 0.24 to 0.362, preferably can be in the range of 0.27 to 0.331 and more preferably can be in the range of 0.300 to 0.301.

[1219] IVfralient in kg / s may be in the range of 0.196 to 0.311, preferably may be in the range of 0.220 to 0.285 and more preferably can be in the range of 0.245 to 0.259.

[1220] WfjnaxTO in ^g / s can be in the range of 1.68 to 4.20, preferably can be in the range of 1.89 to 3.85 and preferably in the range of 2.10 to 3.50.

[1221] IVfjnaxTO in ^g / s can be in the range of 1.92 to 4.20, preferably can be in the range of 2.16 to 3.85 and more preferably can be in the range of 2.41 to 3.50.

[1222] IVen ^g / s may be in the range of 1.92 to 3.39, preferably may be in the range of 2.16 to 3.11 and more preferably may be in the range of 2.41 to 2.82.

[1223] IVf ^axTO in kg / s can be in the range of 1.68 to 3.45, preferably can be in the range of 1.89 to 3.16 and preferably in the range of 2.10 to 2.88.

[1224] IVf^axTO in kg / s can be in the range of 1.92 to 3.13, preferably can be in the range of 2.16 to 2.87 and more preferably can be in the range of 2.41 to 2.61.

[1225] IVfjnaxTO in kg / s can be in the range of 2.25 to 3.39, preferably can be in the range of 2.53 to 3.11 and more preferably can be in the range of 2.81 to 2.82.

[1226] IVfjaaxTO in kg / s can be in the range of 2.79 to 4.20, preferably can be in the range of 3.14 to 3.85 and more preferably can be in the range of 3.49 to 3.50.

[1227] IVfjjiaxTO in kg / s May be in the range of 1.83 to 3.01, preferably may be in the range of 2.05 to 2.76 and preferably in the range of 2.28 to 2.51.

[1228] According to a fifty-sixth aspect, a method of operating the gas turbine engine of the fifty-fifth aspect is provided, the method comprising supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1229] According to a fifty-seventh aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1230] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1231] A fuel flow rate nvPM emission index ratio can be defined as:

[1232] [Math. 128] slow motion^^f slow motion maxTC^ f, maxTO

[1233] where:

[1234] Δ / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[1235] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 100% of the available thrust for the given operating conditions;

[1236] Wft raiti is the fuel flow to the fuel spray nozzles in kg / s at approximately 7% of the thrust available for the given operating conditions; and

[1237] IV fjnaxTO is the fuel flow rate to the fuel spray nozzles in kg / s at approximately 100% of the available thrust for the given operating conditions;

[1238] the nvPM emission index ratio of the gas turbine engine fuel flow rate is less than 0.2; and

[1239] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1240] Any ratio of the nvPM emission index of the fuel flow, Wf idle ct ^f^naxTO May be as defined above in relation to the fifty-fifth aspect.

[1241] According to a fifty-eighth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1242] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1243] A thrust nvPM emission index ratio can be defined as:

[1244] [Math. 129]

[1245] where:

[1246] Ê / raienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine if it is operating at about 7% of available thrust for given operating conditions;

[1247] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 100% of the available thrust for the given operating conditions;

[1248] FmaxTO is 'a Thrust of the gas turbine engine at approximately 100% of the available thrust in kN under the given operating conditions; and

[1249] Fraient! is 'a Thrust of the gas turbine engine at about 7% of the available thrust in kN under the given operating conditions;

[1250] the nvPM thrust emission index ratio is greater than 0.05; and

[1251] The gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1252] The nvPM thrust emission index ratio may be greater than 0.0535 and preferably may be greater than 0.0602 and more preferably may be greater than 0.0669.

[1253] The nvPM thrust emission index ratio may be greater than 0.07 and preferably may be greater than 0.0788 and more preferably may be greater than 0.0875.

[1254] The nvPM thrust emission index ratio may be greater than 0.0588 and preferably may be greater than 0.0662 and more preferably may be greater than 0.0736.

[1255] The nvPM thrust emission index ratio may be greater than 0.162 and preferably may be greater than 0.182 and more preferably may be greater than 0.202.

[1256] The nvPM thrust emission index ratio may be greater than 0.0849 and preferably may be greater than 0.0956 and more preferably may be greater than 0.106.

[1257] The nvPM thrust emission index ratio may be greater than or equal to 0.1 and preferably may be greater than or equal to 0.2 and more preferably may be greater than or equal to 0.3.

[1258] The nvPM thrust emission index ratio may be greater than or equal to 0.36 and preferably may be greater than or equal to 0.405 and more preferably may be greater than or equal to 0.451.

[1259] The nvPM thrust emission index ratio may be greater than or equal to 0.472 and preferably may be greater than or equal to 0.531 and more preferably may be greater than or equal to 0.59.

[1260] The nvPM thrust emission index ratio may be greater than or equal to 0.397 and preferably may be greater than or equal to 0.446 and more preferably may be greater than or equal to 0.496.

[1261] The nvPM thrust emission index ratio may be greater than or equal to 1.09 and preferably may be greater than or equal to 1.22 and more preferably may be greater than or equal to 1.36.

[1262] The nvPM thrust emission index ratio may be greater than or equal to 0.572 and preferably may be greater than or equal to 0.644 and more preferably may be greater than or equal to 0.716.

[1263] The nvPM thrust emission index ratio may be less than or equal to 1.64 and preferably may be less than or equal to 1.51 and more preferably may be less than or equal to 1.37.

[1264] The nvPM thrust emission index ratio may be less than or equal to 0.703 and preferably may be less than or equal to 0.645 and more preferably may be less than or equal to 0.586.

[1265] The nvPM thrust emission index ratio may be less than or equal to 1.32 and preferably may be less than or equal to 1.21 and more preferably may be less than or equal to 1.1.

[1266] The nvPM thrust emission index ratio may be less than or equal to 0.542 and preferably may be less than or equal to 0.497 and more preferably may be less than or equal to 0.452.

[1267] The nvPM thrust emission index ratio may be less than or equal to 1.64 and preferably may be less than or equal to 1.51 and more preferably may be less than or equal to 1.37.

[1268] The nvPM thrust emission index ratio may be less than or equal to 1.29 and preferably may be less than or equal to 1.18 and more preferably may be less than or equal to 1.07.

[1269] The nvPM thrust emission index ratio may be greater than 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2 or any range defined between any two of these values.

[1270] The ratio of the nvPM thrust emission index may be in the range of 0.36 to 1.64 and preferably in the range of 0.405 to 1.51 and more preferably in the range of 0.451 to 1.37.

[1271] The ratio of the nvPM thrust emission index may be in the range of 0.36 to 0.703 and preferably in the range of 0.405 to 0.645 and more preferably in the range of 0.451 to 0.586.

[1272] The ratio of the nvPM thrust emission index may be in the range of 0.472 to 1.32 and preferably in the range of 0.531 to 1.21 and more preferably in the range of 0.59 to 1.1.

[1273] The ratio of the nvPM thrust emission index may be in the range of 0.397 to 0.703 and preferably in the range of 0.446 to 0.645 and more preferably in the range of 0.496 to 0.586.

[1274] The ratio of the nvPM thrust emission index may be in the range of 0.360 to 0.542 and preferably in the range of 0.405 to 0.497 and more preferably in the range of 0.451 to 0.452.

[1275] The ratio of the nvPM thrust emission index may be in the range of 1.09 to 1.64 and preferably in the range of 1.22 to 1.51 and more preferably in the range of 1.36 to 1.37.

[1276] The ratio of the nvPM thrust emission index may be in the range of 0.572 to 1.29 and preferably in the range of 0.644 to 1.18 and more preferably in the range of 0.716 to 1.07.

[1277] ^niaxTO in May be in 'a P'a8c from 229 to 525, preferably may be in the range from 258 to 481 and more preferably may be in the range from 287 to 437.

[1278] FmaxTO may be in the range of 267 to 525, preferably may be in the range of 300 to 481 and more preferably may be in the range of 334 to 437.

[1279] FmaxTO can be in 'a P'a8c from 267 to 455, preferably can be in the range from 300 to 417 and more preferably can be in the range from 334 to 380.

[1280] FmaxTO may be in 'a P'a8c from 229 to 437, preferably may be in the range from 258 to 401 and more preferably may be in the range from 287 to 364.

[1281] FmaxTO may be in 'a P'a8c from 267 to 427, preferably may be in the range of 300 to 391 and more preferably can be in the range of 334 to 356.

[1282] FBiaxTO in kN may be in the range of 303 to 455, preferably may be in the range of 341 to 417 and more preferably may be in the range of 379 to 380.

[1283] FlnaxTO in kN may be in the range of 349 to 525, preferably may be in the range of 393 to 481 and more preferably may be in the range of 436 to 437.

[1284] FniaxTO in kN may be in the range of 246 to 394, preferably may be in the range of 277 to 361 and more preferably may be in the range of 308 to 328.

[1285] -Fraitsi en may be in the range of 16.0 to 36.7, preferably may be in the range of 18.0 to 33.7 and more preferably may be in the range of 20.0 to 30.6.

[1286] F slowed down in May be in the range of 18.7 to 36.7, preferably may be in the range of 21.0 to 33.7 and more preferably can be in the range of 23.3 to 30.6.

[1287] ^slowed down Can be in the range of 18.7 to 31.9, preferably can be in the range of 21.0 to 29.2 and more preferably can be in the range of 23.3 to 26.6.

[1288] F slowed down in May be in the range of 16.0 to 30.6, preferably may be in the range of 18.0 to 28.1 and more preferably can be in the range of 20.0 to 25.5.

[1289] P slowed down in May be in the range of 18.7 to 29.9, preferably may be in the range of 21.0 to 27.4 and more preferably can be in the range of 23.3 to 24.9.

[1290] Fralient en Can be in the range of 21.2 to 31.9, preferably can be in the range of 23.8 to 29.2 and more preferably can be in the range of 26.5 to 26.6.

[1291] F slowed down in May be in the range of 24.4 to 36.7, preferably may be in the range of 27.5 to 33.7 and more preferably can be in the range of 30.5 to 30.6.

[1292] Frequent in kN may be in the range of 17.2 to 27.6, preferably may be in the range of 19.4 to 25.3 and more preferably may be in the range of 21.6 to 23.0.

[1293] According to a fifty-ninth aspect, a method of operating the gas turbine engine of the fifty-eighth aspect is provided, the method comprising supplying fuel comprising a durable aviation fuel to the plurality of fuel spray nozzles.

[1294] According to a sixtieth aspect, a method of operating a gas turbine engine is provided, the gas turbine engine comprising:

[1295] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1296] A thrust nvPM emission index ratio can be defined as:

[1297] [Math. 130] Eiinrs / p ________ / 1 maxTO Fraîenti / -R, / slow motion

[1298] where:

[1299] ^fraîenti is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it operates at approximately 7% of the available thrust for given operating conditions; and

[1300] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine if it is operating at about 100% of the available thrust for the given operating conditions;

[1301] FniaxTO is the thrust of the gas turbine engine at approximately 100% of the thrust available in kN under given operating conditions,

[1302] F idle is 'a Gas turbine engine thrust at about 7% of the thrust available in kN under the given operating conditions; and

[1303] the nvPM thrust emission index ratio is greater than 0.05; and

[1304] The process includes the supply of fuel comprising aviation fuel durable to the plurality of fuel spray nozzles.

[1305] Any ratio of the nvPM thrust emission index, Finax and F idle can be tc' 9ue defined above in relation to the fifty-eighth aspect.

[1306] According to a sixty-first aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1307] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1308] A depleted cruise nvPM-PMD emission index ratio can be defined as:

[1309] [Math. 131] cTolsière [impoverished^ni

[1310] where:

[1311] E / cruise (impoverished) can be defined as:

[1312] [Math.132] pr _ ±pT max i OJ ascent 2

[1313] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust for given operating conditions;

[1314] EImontée is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust for the given operating conditions; and

[1315] BPR is the gas turbine engine dilution ratio;

[1316] the ratio of the nvPM emissions index in depleted cruise to PMD is less than 0.2; and

[1317] The gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1318] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.194 and preferably may be less than 0.178 and more preferably may be less than 0.162.

[1319] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.19 and preferably may be less than 0.174 and more preferably may be less than 0.158.

[1320] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.181 and preferably may be less than 0.166 and more preferably may be less than 0.151.

[1321] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.172 and preferably may be less than 0.158 and more preferably may be less than 0.144.

[1322] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.14 and preferably may be less than 0.128 and more preferably may be less than 0.117.

[1323] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.18 and preferably may be less than or equal to 0.16 and more preferably may be less than or equal to 0.14.

[1324] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.16 and preferably may be less than or equal to 0.147 and more preferably may be less than or equal to 0.134.

[1325] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.151 and preferably may be less than or equal to 0.138 and more preferably may be less than or equal to 0.126.

[1326] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.145 and preferably may be less than or equal to 0.133 and more preferably may be less than or equal to 0.121.

[1327] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.123 and preferably may be less than or equal to 0.112 and more preferably may be less than or equal to 0.102.

[1328] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than or equal to 0.157 and preferably may be less than or equal to 0.144 and more preferably may be less than or equal to 0.131.

[1329] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.0814 and preferably may be greater than or equal to 0.0915 and more preferably may be greater than or equal to 0.101.

[1330] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.096 and preferably may be greater than or equal to 0.108 and more preferably may be greater than or equal to 0.12.

[1331] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.0958 and preferably may be greater than or equal to 0.107 and more preferably may be greater than or equal to 0.119.

[1332] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.0979 and preferably may be greater than or equal to 0.11 and more preferably may be greater than or equal to 0.122.

[1333] The ratio of the nvPM emissions index in depleted cruise-PMD may be greater than or equal to 0.0961 and preferably may be greater than or equal to 0.108 and more preferably may be greater than or equal to 0.12.

[1334] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0814 to 0.160 and preferably may be in the range of 0.0915 to 0.147 and, more preferably, may be in the range of 0.101 to 0.134.

[1335] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0814 to 0.151 and preferably may be in the range of 0.0915 to 0.138 and, more preferably, may be in the range of 0.101 to 0.126.

[1336] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0960 to 0.151 and preferably may be in the range of 0.108 to 0.138 and, more preferably, may be in the range of 0.120 to 0.126.

[1337] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0958 to 0.160 and preferably may be in the range of 0.107 to 0.147 and, more preferably, may be in the range of 0.119 to 0.134.

[1338] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0979 to 0.151 and preferably may be in the range of 0.110 to 0.138 and, more preferably, may be in the range of 0.122 to 0.126.

[1339] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0960 to 0.145 and preferably may be in the range of 0.108 to 0.133 and, more preferably, may be in the range of 0.120 to 0.121.

[1340] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0814 to 0.123 and preferably may be in the range of 0.0915 to 0.112 and, more preferably, may be in the range of 0.101 to 0.102.

[1341] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0961 to 0.160 and preferably may be in the range of 0.108 to 0.147 and, more preferably, may be in the range of 0.120 to 0.134.

[1342] The ratio of the nvPM emissions index in depleted cruise-PMD may be in the range of 0.0958 to 0.157 and preferably may be in the range of 0.107 to 0.144 and, more preferably, may be in the range of 0.119 to 0.131.

[1343] The ratio of the nvPM emissions index in depleted cruise-PMD may be less than 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.2, or within any defined range between any two of these values.

[1344] The BPR may be in the range of 6.44 to 11.2 and preferably may be in the range of 7.25 to 10.3 and more preferably may be in the range of 8.05 to 9.29.

[1345] The BPR may be in the range of 7.20 to 11.2 and preferably may be in the range of 8.10 to 10.3 and more preferably may be in the range of 9.01 to 9.28.

[1346] The BPR may be in the range of 7.10 to 11.2 and preferably may be in the range of 7.99 to 10.3 and more preferably may be in the range of 8.88 to 9.29.

[1347] The BPR may be in the range of 7.32 to 11.2 and preferably may be in the range of 8.23 ​​to 10.3 and more preferably may be in the range of 9.15 to 9.28.

[1348] The BPR may be in the range of 7.20 to 10.9 and preferably may be in the range of 8.10 to 9.92 and more preferably may be in the range of 9.00 to 9.02.

[1349] The BPR may be in the range of 6.44 to 9.68 and preferably may be in the range of 7.25 to 8.87 and more preferably may be in the range of 8.05 to 8.06.

[1350] The BPR may be in the range of 7.15 to 11.1 and preferably may be in the range of 8.04 to 10.2 and more preferably may be in the range of 8.93 to 9.19.

[1351] A rich cruise nvPM-PMD emission index ratio can be defined as:

[1352] [Math. 133] BPR

[1353] where:

[1354] £' / cruise (rich) can be defined as:

[1355] [Math. 134] El - +EI > climb^^1 approach 2

[1356] EImontée is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or for different given operating conditions;

[1357] ^fapproach is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same operating conditions at which EImontée is calculated; and

[1358] £7maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée is calculated; and

[1359] in which the rich cruise nvPM-PMD emission index ratio is less than 0.4.

[1360] The rich cruise nvPM-PMD emission index ratio may be less than 0.38 and preferably may be less than 0.36, and more preferably may be less than 0.34.

[1361] The rich cruise nvPM-PMD emission index ratio may be less than 0.323 and preferably may be less than 0.296 and more preferably may be less than 0.269.

[1362] The rich cruise nvPM-PMD emission index ratio may be less than 0.307 and preferably may be less than 0.282 and more preferably may be less than 0.256.

[1363] The rich cruise nvPM-PMD emission index ratio may be less than 0.298 and preferably may be less than 0.273, and more preferably may be less than 0.248.

[1364] The rich cruise nvPM-PMD emission index ratio may be less than 0.277 and preferably may be less than 0.254 and more preferably may be less than 0.231.

[1365] The rich cruise nvPM-PMD emission index ratio may be less than 0.211 and preferably may be less than 0.193 and more preferably may be less than 0.176.

[1366] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.13 and preferably may be less than or equal to 0.119 and more preferably may be less than or equal to 0.108.

[1367] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.129 and preferably may be less than or equal to 0.119 and more preferably may be less than or equal to 0.108.

[1368] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.128 and preferably may be less than or equal to 0.118 and more preferably may be less than or equal to 0.107.

[1369] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.0823 and preferably may be less than or equal to 0.0754 and more preferably may be less than or equal to 0.0686.

[1370] The rich cruise nvPM-PMD emission index ratio may be less than or equal to 0.129 and preferably may be less than or equal to 0.118 and more preferably may be less than or equal to 0.108.

[1371] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.0548 and preferably may be greater than or equal to 0.0616 and more preferably may be greater than or equal to 0.0685.

[1372] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.0773 and preferably may be greater than or equal to 0.087 and more preferably may be greater than or equal to 0.0966.

[1373] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.0633 and preferably may be greater than or equal to 0.0712 and more preferably may be greater than or equal to 0.0791.

[1374] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.086 and preferably may be greater than or equal to 0.0968 and more preferably may be greater than or equal to 0.107.

[1375] The rich cruise nvPM-PMD emission index ratio may be greater than or equal to 0.0676 and preferably may be greater than or equal to 0.0761 and more preferably may be greater than or equal to 0.0845.

[1376] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0548 to 0.130 and preferably may be in the range of 0.0616 to 0.119 and, more preferably, may be in the range of 0.0685 to 0.108.

[1377] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0773 to 0.130 and preferably may be in the range of 0.0870 to 0.119 and, more preferably, may be in the range of 0.0966 to 0.108.

[1378] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0633 to 0.129 and preferably may be in the range of 0.0712 to 0.119 and, more preferably, may be in the range of 0.0791 to 0.108.

[1379] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0773 to 0.128 and preferably may be in the range of 0.0870 to 0.118 and, more preferably, may be in the range of 0.0966 to 0.107.

[1380] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0860 to 0.130 and preferably may be in the range of 0.0968 to 0.119 and, more preferably, may be in the range of 0.107 to 0.108.

[1381] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0548 to 0.0823 and preferably may be in the range of 0.0616 to 0.0754 and, more preferably, may be in the range of 0.0685 to 0.0686.

[1382] The rich cruise nvPM-PMD emission index ratio may be in the range of 0.0676 to 0.129 and preferably may be in the range of 0.0761 to 0.119 and, more preferably, may be in the range of 0.0845 to 0.108.

[1383] The rich cruise nvPM-PMD emission index ratio may be less than 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, or within any defined range between any two of these values.

[1384] According to a sixty-second aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1385] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1386] A rich-cruising nvPM-PMD emission index ratio can be defined as:

[1387] [Math. 135] BPR

[1388] where:

[1389] ^' / cruise (rich) Pcul to be defined as:

[1390] [Math. 136] pi, +pj, ^oatee^^1 approach 2

[1391] £7mOntée is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions;

[1392] ^fapproach is the nvPM emissions index corrected for system losses in mg / kg of the gas turbine engine when operating at about 30% of available thrust under the same operating conditions at which EImontée is calculated;

[1393] £7maxTo is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EImontée is calculated;

[1394] BPR is the gas turbine engine dilution ratio;

[1395] the ratio of the nvPM emissions index in rich cruise to PMD is less than 0.4; and

[1396] The gas turbine engine is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles.

[1397] The rich cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the sixty-first aspect.

[1398] According to a sixty-third aspect, a method of operating the gas turbine engine of the sixty-first or sixty-second aspect is provided, the method comprising supplying fuel comprising a durable aviation fuel to the plurality of fuel spray nozzles.

[1399] According to a sixty-fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1400] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1401] A depleted cruise nvPM-PMD emission index ratio can be defined as:

[1402] [Math. 137] Elcroisière [impoverished] / p / — kmy '-^si&xTQ BPR

[1403] where:

[1404] Elcroisière (impoverished) can be defined as:

[1405] [Math. 138] PI ±PI 2 max TO'^1 ascent 2

[1406] S / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust for given operating conditions;

[1407] Ê / rise is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of the available thrust for the given operating conditions; and

[1408] BPR is the gas turbine engine dilution ratio;

[1409] the ratio of the nvPM emissions index in depleted cruise to PMD is less than 0.2; and

[1410] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1411] The depleted cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the sixty-first aspect.

[1412] A rich-cruising nvPM-PMD emission index ratio can be defined as:

[1413] [Math. 139] Elcroisièrse {richeiE Fl — ____________ / —'■'maxiO BPR

[1414] where:

[1415] ^ / cruise (rich) can be defined as:

[1416] [Math. 140] FI, +FI! JJ is approaching 2

[1417] EImontée is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 85% of the available thrust for given operating conditions, or for different given operating conditions;

[1418] ^' / approach is the nvPM emissions index corrected for system losses in mg / kg of the gas turbine engine when operating at about 30% of available thrust under the same operating conditions at which EImontée is calculated;

[1419] S / maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under the same operating conditions at which EImontée is calculated; and

[1420] in which the rich cruise nvPM-PMD emission index ratio may be less than 0.4.

[1421] The rich cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the sixty-first aspect.

[1422] According to a sixty-fifth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1423] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1424] A rich-cruising nvPM-PMD emission index ratio can be defined as:

[1425] [Math. 141] BPR

[1426] where:

[1427] E / cruise (rich) can be defined as:

[1428] [Math. 142] FJ, +FÏ 1 mountain, 1 approach 2

[1429] EImontée is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions;

[1430] ^ / approach is the nvPM emissions index corrected for system losses in mg / kg of the gas turbine engine when operating at about 30% of available thrust under the same operating conditions at which EImontée is calculated;

[1431] Ê / maxTo is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine when operating at about 100% of available thrust under the same operating conditions at which EImontée is calculated;

[1432] BPR is the gas turbine engine dilution ratio;

[1433] the ratio of the rich-PMD nvPM emission index is less than 0.4; and

[1434] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1435] The rich cruise nvPM-PMD emission index ratio and / or the BPR may be as defined above in relation to the sixty-first aspect.

[1436] According to a sixty-sixth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1437] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1438] A PMD nvPM emission index ratio can be defined as:

[1439] [Math. 143] EIïnaxTQ, SAP TO,PF

[1440] where:

[1441] ^7maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1442] ^7maxTo,FF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[1443] the nvPM PMD emission index ratio of the gas turbine engine is less than 1; and

[1444] The gas turbine engine is designed to supply fuel comprising a SAF to the plurality of fuel spray nozzles.

[1445] The nvPM PMD emission index ratio may be greater than zero.

[1446] The PMD nvPM emission index ratio may be less than or equal to 0.93 and preferably may be less than or equal to 0.86 and more preferably may be less than or equal to 0.79.

[1447] The nvPM PMD emission index ratio may be less than or equal to 0.776, and preferably may be less than or equal to 0.711, and more preferably may be less than or equal to 0.646.

[1448] The nvPM PMD emission index ratio may be greater than or equal to 0.15, and preferably may be greater than or equal to 0.3, and more preferably may be greater than or equal to 0.45.

[1449] The nvPM PMD emission index ratio may be greater than or equal to 0.516, and preferably may be greater than or equal to 0.581, and more preferably may be greater than or equal to 0.645.

[1450] The nvPM PMD emission index ratio may be in the range of 0.516 to 0.776, and preferably may be in the range of 0.581 to 0.711, and more preferably may be in the range of 0.645 to 0.646.

[1451] The PMD nvPM emission index ratio may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any range defined between any two of these values.

[1452] The PMD nvPM emission index ratio may be 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, or within any range defined between any two of these values.

[1453] A rise nvPM emission index ratio can be defined as:

[1454] [Math. 144] SAP FI J inontee^F

[1455] where:

[1456] £7,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1457] £7 rise jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same given operating conditions at which EI rise jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[1458] and in which the rise-up nvPM emission index ratio of the gas turbine engine may be less than 1.

[1459] The rise nvPM emission index ratio may be greater than zero.

[1460] The rise nvPM emission index ratio may be less than or equal to 0.9, and preferably may be less than or equal to 0.75, and more preferably may be less than or equal to 0.6.

[1461] The rise nvPM emission index ratio may be less than or equal to 0.57, and preferably may be less than or equal to 0.523, and more preferably may be less than or equal to 0.475.

[1462] The rise nvPM emission index ratio may be greater than or equal to 0.1, and preferably may be greater than or equal to 0.2, and more preferably may be greater than or equal to 0.3.

[1463] The rise nvPM emission index ratio may be greater than or equal to 0.379, and preferably may be greater than or equal to 0.427, and more preferably may be greater than or equal to 0.474.

[1464] The rise nvPM emission index ratio may be in the range of 0.379 to 0.570, and preferably may be in the range of 0.427 to 0.523, and more preferably may be in the range of 0.474 to 0.475.

[1465] The rise nvPM emission index ratio may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any range defined between any two of these values.

[1466] The rise nvPM emission index ratio may be 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, or within any defined range between any two of these values.

[1467] An approach nvPM emission index ratio can be defined as:

[1468] [Math. 145] The approach, SAF The approach, FF

[1469] where:

[1470] £7 approach, SAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1471] Δ / approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which Δ7approach ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[1472] in which the approach nvPM emission index ratio of the gas turbine engine may be less than 1.

[1473] The approach nvPM emission index ratio may be greater than zero.

[1474] The approach nvPM emission index ratio may be less than or equal to 0.8, and preferably may be less than or equal to 0.5, and more preferably may be less than or equal to 0.2.

[1475] The approach nvPM emission index ratio may be less than or equal to 0.185, and preferably may be less than or equal to 0.169, and more preferably may be less than or equal to 0.154.

[1476] The approach nvPM emission index ratio may be greater than or equal to 0.03, and preferably may be greater than or equal to 0.06, and more preferably may be greater than or equal to 0.09.

[1477] The approach nvPM emission index ratio may be greater than or equal to 0.122, and preferably may be greater than or equal to 0.138, and more preferably may be greater than or equal to 0.153.

[1478] The approach nvPM emission index ratio may be in the range of 0.122 to 0.185, and preferably may be in the range of 0.138 to 0.169, and more preferably may be in the range of 0.153 to 0.154.

[1479] The approach nvPM emission index ratio may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any range defined between any two of these values.

[1480] The approach nvPM emission index ratio may be 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or within any defined range between any of these values.

[1481] An nvPM emission index ratio at idle can be defined as:

[1482] [Math. 146] SAF ^^inontée.FF

[1483] where:

[1484] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust for given operating conditions, or for different given operating conditions, and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1485] Ê / raienti jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which ELaiemi ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[1486] in which the nvPM emission index ratio at idle of the gas turbine engine may be less than 1.

[1487] The nvPM emission index ratio at idle may be greater than zero.

[1488] The nvPM emission index ratio at idle may be less than or equal to 0.8, and preferably may be less than or equal to 0.5, and more preferably may be less than or equal to 0.2.

[1489] The nvPM emission index ratio at idle may be less than or equal to 0.115, and preferably may be less than or equal to 0.106, and more preferably may be less than or equal to 0.0959.

[1490] The nvPM emission index ratio at idle may be greater than or equal to 0.02, and preferably may be greater than or equal to 0.04, and more preferably may be greater than or equal to 0.06.

[1491] The nvPM emission index ratio at idle may be greater than or equal to 0.0766, and preferably may be greater than or equal to 0.0862, and more preferably may be greater than or equal to 0.0958.

[1492] The nvPM emission index ratio at idle may be in the range of 0.0766 to 0.115 and preferably may be in the range of 0.0862 to 0.106 and more preferably may be in the range of 0.0958 to 0.0959.

[1493] The nvPM emission index ratio at idle may be less than 1, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or 0.05, or any range defined between any two of these values.

[1494] The nvPM emission index ratio at idle may be 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or within any defined range between any two of these values.

[1495] According to a sixty-seventh aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1496] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1497] A rise nvPM emission index ratio can be defined as:

[1498] [Math. 147] SAF ^^inontée.FF

[1499] where:

[1500] £7,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1501] £7 rise jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for the same given operating conditions at which EI^^ >Saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[1502] the gas turbine engine's climb nvPM emission index ratio is less than 1; and

[1503] The gas turbine engine is designed to supply fuel comprising an S AF to the plurality of fuel spray nozzles.

[1504] The rise nvPM emission index ratio may be as defined in relation to the sixty-sixth aspect.

[1505] According to a sixty-eighth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1506] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1507] An approach nvPM emission index ratio can be defined as:

[1508] [Math. 148] The approach, SAF TT 2 approach,FF

[1509] where:

[1510] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1511] ^' / approach jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust for the same given operating conditions at which £7approach ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[1512] the approach nvPM emission index ratio of the gas turbine engine is less than 1; and

[1513] The gas turbine engine is designed to supply fuel comprising a SAF to the plurality of fuel spray nozzles.

[1514] The approach nvPM emission index ratio may be as defined above in relation to the sixty-sixth aspect.

[1515] According to a sixty-ninth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1516] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1517] An NVPM emission index ratio at idle can be defined as:

[1518] [Math. 149] The slowdown, SAP Elralenti.PP

[1519] where:

[1520] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1521] Ê / raienti jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 7% of available thrust for the same given operating conditions at which EIialeaü jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[1522] the nvPM emission index ratio at idle of the gas turbine engine is less than 1; and

[1523] The gas turbine engine is designed to supply fuel comprising a SAF to the plurality of fuel spray nozzles.

[1524] The nvPM emission index ratio at idle can be as defined in relation to the sixty-sixth aspect.

[1525] According to a seventieth aspect, a method of operating the gas turbine engine of any of the sixty-sixth, sixty-seventh, sixty-eighth or sixty-ninth aspects is provided, the method comprising supplying fuel comprising a durable aviation fuel to the plurality of fuel spray nozzles.

[1526] According to a seventy-first aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1527] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1528] A PMD nvPM emission index ratio can be defined as:

[1529] [Math. 150] ElmaxTO, SAF E EnsxT O, PP

[1530] where:

[1531] £' / maxTo,sAF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1532] £7maxTo,FF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel;

[1533] the nvPM PMD emission index ratio of the gas turbine engine is less than 1; and

[1534] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1535] The nvPM PMD emission index ratio can be as defined in relation to the sixty-sixth aspect.

[1536] A rise nvPM emission index ratio can be defined as:

[1537] [Math. 151] 17 T 1 climb, SAF —y Ascent? F

[1538] where:

[1539] £7,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1540] £7montée ,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust under the same given operating conditions at which EImontée Saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[1541] The nvPM climb emission index ratio of the gas turbine engine may be less than 1.

[1542] The rise nvPM emission index ratio may be as defined in relation to the sixty-sixth aspect.

[1543] An approach nvPM emission index ratio can be defined as:

[1544] [Math. 152] EIapproche, SAF The approach, FF

[1545] where:

[1546] ^ / approach,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1547] £7approx. jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which £7approx. ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and in which

[1548] and in which the approach nvPM emission index ratio of the gas turbine engine may be less than 1.

[1549] The approach nvPM emission index ratio may be as defined in relation to the sixty-sixth aspect.

[1550] An nvPM emission index ratio at idle can be defined as:

[1551] [Math. 153] The slowdown, SAP pi raiti^ F

[1552] where:

[1553] Ê / raienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust for given operating conditions, or for different given operating conditions, and if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1554] EZraienü ,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which EIiaienti ,Sai is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[1555] in which the nvPM emission index ratio at idle of the gas turbine engine may be less than 1.

[1556] The nvPM emission index ratio at idle can be as defined in relation to the sixty-sixth aspect.

[1557] According to a seventy-second aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1558] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1559] A rise nvPM emission index ratio can be defined as:

[1560] [Math. 154] El montée, SAP pj *niontee,FF

[1561] where:

[1562] Ê / climb,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1563] Ί / rise jf is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 85% of available thrust for the same given operating conditions at which EIrise jSaf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;

[1564] the nvPM climb emission index ratio of the gas turbine engine is less than 1; and

[1565] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1566] The rise nvPM emission index ratio can be as defined in relation to the sixty-sixth aspect.

[1567] According to a seventy-third aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1568] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1569] An approach nvPM emission index ratio can be defined as:

[1570] [Math. 155] EIapproche, SAP The approach, FF

[1571] where:

[1572] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles include sustainable aviation fuel (SAF); and

[1573] £7approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust under the same given operating conditions at which £7approach ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[1574] the approach nvPM emission index ratio of the gas turbine engine is less than 1; and

[1575] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1576] The approach nvPM emission index ratio may be as defined in relation to the sixty-sixth aspect.

[1577] According to a seventy-fourth aspect, a method for operating a gas turbine engine is provided, the gas turbine engine comprising:

[1578] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1579] An NVPM emission index ratio at idle can be defined as:

[1580] [Math. 156] they would say!, SAP El slowed down,FF

[1581] where:

[1582] ÊLaienti ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and

[1583] Ê / raienti ,ff is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 7% of available thrust under the same given operating conditions at which ELaiemi ,saf is calculated and if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[1584] the nvPM emission index ratio at idle of the gas turbine engine is less than 1; and

[1585] The method includes supplying fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.

[1586] The nvPM emission index ratio at idle can be as defined in relation to the sixty-sixth aspect.

[1587] According to a seventy-fifth aspect, a gas turbine engine for an aircraft is supplied, comprising any of the following features:

[1588] a combustor device comprising a combustion chamber and a plurality of fuel spray nozzles designed to inject fuel into the combustion chamber; and wherein:

[1589] A fuel flow rate modified by an nvPM PMD emission index ratio can be defined as:

[1590] [Math. 157] ElmaxTO, SAF t EImaxTo,FF X Wf,maxTO

[1591] where:

[1592] ^7maxTo,sAF is the system loss corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 100% of available thrust for given operating conditions if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF);

[1593] ^7maxTo,FF is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 100% of available thrust under given operating conditions if a fuel supplied to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and

[1594] IVf^axTO is the mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at approximately 100% of the available thrust for the given operating conditions;

[1595] the fuel flow rate modified by a ratio of the nvPM PMD emission index of the gas turbine engine in kg / s is less than 5; and

[1596] The gas turbine engine is designed to supply fuel comprising a SAF to the plurality of fuel spray nozzles.

[1597] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than zero.

[1598] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than 4.2, and preferably may be less than 3.85 and more preferably may be less than 3.5.

[1599] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than 3.39 and preferably may be less than 3.11 and more preferably may be less than 2.82.

[1600] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than 3.45 and preferably may be less than 3.16 and more preferably may be less than 2.88.

[1601] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than 3.13, and preferably may be less than 2.87 and more preferably may be less than 2.61.

[1602] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than 3.01 and preferably may be less than 2.76 and more preferably may be less than 2.51.

[1603] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 2.72 and preferably may be less than or equal to 2.49 and more preferably may be less than or equal to 2.26.

[1604] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 2.19 and preferably may be less than or equal to 2.01 and more preferably may be less than or equal to 1.83.

[1605] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 2.23 and preferably may be less than or equal to 2.05 and more preferably may be less than or equal to 1.86.

[1606] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 2.02 and preferably may be less than or equal to 1.85 and more preferably may be less than or equal to 1.69.

[1607] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be less than or equal to 1.94 and preferably may be less than or equal to 1.78 and more preferably may be less than or equal to 1.62.

[1608] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 1.45 and preferably may be greater than or equal to 1.63 and more preferably may be greater than or equal to 1.82.

[1609] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 1.08 and preferably may be greater than or equal to 1.22 and more preferably may be greater than or equal to 1.36.

[1610] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 1.24 and preferably may be greater than or equal to 1.4 and more preferably may be greater than or equal to 1.55.

[1611] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 1.8 and preferably may be greater than or equal to 2.03 and more preferably may be greater than or equal to 2.25.

[1612] The fuel flow rate modified by an emission index ratio of nvPM PMD in kg / s may be greater than or equal to 1.18 and preferably may be greater than or equal to 1.33 and more preferably may be greater than or equal to 1.47.

[1613] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.08 to 2.72 and preferably may be in the range of 1.22 to 2.49 and more preferably may be in the range of 1.36 to 2.26.

[1614] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.24 to 2.72 and preferably may be in the range of 1.40 to 2.49 and more preferably may be in the range of 1.55 to 2.26.

[1615] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.24 to 2.19 and preferably may be in the range of 1.40 to 2.01 and more preferably may be in the range of 1.55 to 1.83.

[1616] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.08 to 2.23 and preferably may be in the range of 1.22 to 2.05 and more preferably may be in the range of 1.36 to 1.86.

[1617] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.24 to 2.02 and preferably may be in the range of 1.40 to 1.85 and more preferably may be in the range of 1.55 to 1.69.

[1618] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.45 to 2.19 and preferably may be in the range of 1.63 to 2.01 and more preferably may be in the range of 1.82 to 1.83.

[1619] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.80 to 2.72 and preferably may be in the range of 2.03 to 2.49 and more preferably may be in the range of 2.25 to 2.26.

[1620] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be in the range of 1.18 to 1.94 and preferably may be in the range of 1.33 to 1.78 and more preferably may be in the range of 1.47 to 1.62.

[1621] The fuel flow modified by an emission index ratio of nvPM PMD in kg / s may be 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.25, 4.5, 4.75, 5 or within any range defined between any two of these values.

[1622] IVfjnaxTO in kg / s can be in the range of 1.68 to 4.20, preferably can be in the range of 1.89 to 3.85 and preferably in the range of 2.10 to 3.50.

[1623] Wf^axTO in kg / s can be in the range of 1.92 to 4.20, preferably can be in the range of 2.16 to 3.85 and more preferably can be in the range of 2.41 to 3.50.

[1624]

[1625]

[1626]

[1627]

[1628]

[1629]

[1630]

[1631]

[1632]

[1633]

[1634]

[1635] IVfjjiaxTo in kg / s Can be in the range of 1.92 to 3.39, preferably can be in the range of 2.16 to 3.11 and more preferably can be in the range of 2.41 to 2.82. IVf^axTO in kg / s May be in the range of 1.68 to 3.45, preferably may be in the range of 1.89 to 3.16 and more preferably may be in the range of 2.10 to 2.88. IVfjnaxTO in ^g / s can be in the range of 1.92 to 3.13, preferably can be in the range of 2.16 to 2.87 and more preferably can be in the range of 2.41 to 2.61. IVfjnaxTO in ^g / s can be in the range of 2.25 to 3.39, preferably can be in the range of 2.53 to 3.11 and more preferably can be in the range of 2.81 to 2.82. IV f^axTO in kg / s can be in the range of 2.79 to 4.20, preferably can be in the range of 3.14 to 3.85 and more preferably can be in the range of 3.49 to 3.50. IVf^axTO in kg / s can be in the range of 1.83 to 3.01, preferably can be in the range of 2.05 to 2.76 and more preferably can be in the range of 2.28 to 2.51. IVfjnaxTO in kg / s can be in the range of 1.68 to 3.45, preferably can be in the range of 1.89 to 3.16 and more preferably can be in the range of 2.10 to 2.88. A fuel flow rate modified by an nvPM emissions index ratio of Ascent can be defined as: [Math. 158] E1 T 1 climb, S AF FI ^■monte^FF vv f.montée Or : £7,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust for given operating conditions, or for different given operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and E / rise jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 85% of available thrust under the same operating conditions at which EIrise jSaf is calculated, if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[1636] IVfjnotée is the mass flow rate of fuel supplied to the plurality of nozzles of fuel spray in kg / s when the gas turbine engine is operating at approximately 85% of the available thrust under the same operating conditions for which EImontée jSaf and EImontée >FF are calculated; and in which

[1637] the fuel flow modified by a ratio of the nvPM of climb emission index of the gas turbine engine in kg / s may be less than 4.

[1638] The fuel flow rate modified by a ratio of the nvPM of climb emission index in kg / s may be greater than zero.

[1639] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 3.36 and preferably may be less than 3.08 and more preferably may be less than 2.8.

[1640] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 2.77 and preferably may be less than 2.54 and more preferably may be less than 2.31.

[1641] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 2.79 and preferably may be less than 2.56 and more preferably may be less than 2.33.

[1642] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 2.56 and preferably may be less than 2.35 and more preferably may be less than 2.13.

[1643] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than 2.45 and preferably may be less than 2.25 and more preferably may be less than 2.04.

[1644] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.6 and preferably may be less than or equal to 1.47 and more preferably may be less than or equal to 1.33.

[1645] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.32 and preferably may be less than or equal to 1.21 and more preferably may be less than or equal to 1.1.

[1646] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.33 and preferably may be less than or equal to 1.22 and more preferably may be less than or equal to 1.11.

[1647] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.22 and preferably may be less than or equal to 1.12 and more preferably may be less than or equal to 1.02.

[1648] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be less than or equal to 1.17 and preferably may be less than or equal to 1.07 and more preferably may be less than or equal to 0.969.

[1649] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 0.658 and preferably may be greater than or equal to 0.74 and more preferably may be greater than or equal to 0.822.

[1650] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 0.751 and preferably may be greater than or equal to 0.845 and more preferably may be greater than or equal to 0.939.

[1651] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 0.876 and preferably may be greater than or equal to 0.985 and more preferably may be greater than or equal to 1.09.

[1652] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 1.06 and preferably may be greater than or equal to 1.19 and more preferably may be greater than or equal to 1.32.

[1653] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be greater than or equal to 0.712 and preferably may be greater than or equal to 0.801 and more preferably may be greater than or equal to 0.89.

[1654] The fuel flow modified by a ratio of the nvPM emissions index of climb in kg / s may be in the range of 0.658 to 1.60 and preferably may be in the range of 0.740 to 1.47 and more preferably may be in the range of 0.822 to 1.33.

[1655] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be in the range of 0.751 to 1.60 and preferably may be in the range of 0.845 to 1.47 and more preferably may be in the range of 0.939 to 1.33.

[1656] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be in the range of 0.751 to 1.32 and preferably may be in the range of 0.845 to 1.21 and more preferably may be in the range of 0.939 to 1.10.

[1657] The fuel flow modified by a climb nvPM emission index ratio in kg / s may be in the range of 0.658 to 1.33 and preferably may be in the range of 0.740 to 1.22 and more preferably may be in the range of 0.822 to 1.11.

[1658] The fuel flow modified by a climb nvPM emission index ratio in kg / s may be in the range of 0.751 to 1.22 and preferably may be in the range of 0.845 to 1.12 and more preferably may be in the range of 0.939 to 1.02.

[1659] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be in the range of 0.876 to 1.32 and preferably may be in the range of 0.985 to 1.21 and more preferably may be in the range of 1.09 to 1.10.

[1660] The fuel flow rate modified by a ratio of the nvPM emissions index of climb in kg / s may be in the range of 1.06 to 1.60 and preferably may be in the range of 1.19 to 1.47 and more preferably may be in the range of 1.32 to 1.33.

[1661] The fuel flow rate modified by a climb nvPM emission index ratio in kg / s may be in the range of 0.712 to 1.17 and preferably may be in the range of 0.801 to 1.07 and more preferably may be in the range of 0.890 to 0.969.

[1662] The fuel flow modified by a climb nvPM emission index ratio may be 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4 or within any defined range between any two of these values.

[1663] IVf bridged in kg / s can be in the range of 1.38 to 3.36, preferably can be in the range of 1.55 to 3.08 and preferably in the range of 1.73 to 2.80.

[1664] IV in kg / s may be in the range of 1.58 to 3.36, preferably may be in the range of 1.78 to 3.08 and more preferably may be in the range of 1.97 to 2.80.

[1665] IVfpontée in kg / s can be in the range of 1.58 to 2.77, preferably can be in the range of 1.78 to 2.54 and preferably in the range of 1.97 to 2.31.

[1666] IVfpontée in kg / s can be in the range of 1.38 to 2.79, preferably can be in the range of 1.55 to 2.56 and more preferably can be in the range of 1.73 to 2.33.

[1667] Wfjnoiltée in kg / s can be in the range of 1.58 to 2.56, preferably can be in the range of 1.78 to 2.35 and preferably in the range of 1.97 to 2.13.

[1668] IVfpontée in kg / s can be in the range of 1.84 to 2.77, preferably can be in the range of 2.07 to 2.54 and preferably in the range of 2.30 to 2.31.

[1669] IVfjnoted in kg / s can be in the range of 2.23 to 3.36, preferably can be in the range of 2.51 to 3.08 and preferably in the range of 2.79 to 2.80.

[1670] IVfjnoted in kg / s can be in the range of 1.50 to 2.45, preferably can be in the range of 1.68 to 2.25 and more preferably can be in the range of 1.87 to 2.04.

[1671] A fuel flow rate modified by an approach nvPM emission index ratio can be defined as:

[1672] [Math. 159] approach, SAP ïap pr ach e, FF f, approach

[1673] where:

[1674] Ê / approach ,saf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at approximately 30% of available thrust for the given operating conditions, or for different operating conditions, if a fuel supplied to the plurality of fuel spray nozzles comprises a sustainable aviation fuel; and

[1675] £7approach jf is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine when operating at about 30% of available thrust under the same operating conditions at which £7approach ,saf is calculated if a fuel supplied to the plurality of fuel spray nozzles comprises a fossil-based hydrocarbon fuel; and

[1676] WRapproach is the mass flow rate of fuel supplied to the plurality of nozzles fuel spray in kg / s when the gas turbine engine is operating at approximately 30% of available thrust under the same operating conditions under which £7approach, saf and £7approach jf are calculated; and in which

[1677] the fuel flow modified by an approach nvPM emission index ratio of the gas turbine engine in kg / s may be less than 2.

[1678] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be greater than zero.

[1679] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 1.11 and preferably may be less than 1.01 and more preferably may be less than 0.919.

[1680] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 0.962 and preferably may be less than 0.882 and more preferably may be less than 0.802.

[1681] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 0.893 and preferably may be less than 0.818 and more preferably may be less than 0.744.

[1682] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 0.907 and preferably may be less than 0.832 and more preferably may be less than 0.756.

[1683] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than 0.805 and preferably may be less than 0.738 and more preferably may be less than 0.671.

[1684] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.17 and preferably may be less than or equal to 0.156 and more preferably may be less than or equal to 0.142.

[1685] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.148 and preferably may be less than or equal to 0.136 and more preferably may be less than or equal to 0.124.

[1686] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.138 and preferably may be less than or equal to 0.126 and more preferably may be less than or equal to 0.115.

[1687] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.14 and preferably may be less than or equal to 0.128 and more preferably may be less than or equal to 0.117.

[1688] The fuel flow rate modified by an approach nvPM emission index ratio in kg / s may be less than or equal to 0.124 and preferably may be less than or equal to 0.114 and more preferably may be less than or equal to 0.104. [...

Claims

1. Demands 1 Gas turbine engine (10) for an aircraft, comprising: a combustor device (16), including a combustion chamber (120) and a plurality of fuel spray nozzles (124) designed to inject fuel into the combustion chamber (120), wherein the plurality of fuel spray nozzles (124) comprises a first subset (124A) of fuel spray nozzles (124) and a second subset (124B) of fuel spray nozzles (124), wherein the combustor device (16) can operate under a condition in which each of the fuel spray nozzles of the first subset (124A) of fuel spray nozzles (124) is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset (124B) of fuel spray nozzles (124),wherein a ratio of the number of fuel spray nozzles (124) in the first subset (124A) of fuel spray nozzles (124) to the number of fuel spray nozzles (124) in the second subset (124B) of fuel spray nozzles (124) is in the range of 1:3 to 1:6; and wherein:, A thrust nvPM emission index ratio is defined as: [Math 279] El^«T0 / F:itaxTO pjj • The slow motion / F, / 1 slow motion Idle is the nvPM emission index corrected for system losses in mg / kg of the gas turbine engine (10) if it is operating at about 7% of available thrust under given operating conditions; £7maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine (10) if it is operating at about 100% of available thrust under given operating conditions; ^maxTO is 'a Thrust of the gas turbine engine (10) at about 100% of the available thrust in kN under the given operating conditions; and F idle is 'a Thrust of the gas turbine engine (10) at about 7% of the available thrust in kN under the given operating conditions; the nvPM thrust emission index ratio is greater than 0.02; and the gas turbine engine (10) is designed to supply fuel comprising a sustainable aviation fuel (SAF) to the plurality of fuel spray nozzles (124).

2. 2 Gas turbine engine (10) according to claim 1, wherein the thrust nvPM emission index ratio is greater than 0.0264 and preferably greater than 0.0297 and more preferably greater than 0.

033.

3. 3 Gas turbine engine (10) according to claim 1 or claim 2, wherein the thrust nvPM emission index ratio is greater than 0.0312 and preferably greater than 0.0351 and more preferably greater than 0.

039.

4. 4 Gas turbine engine (10) according to any one of the preceding claims, wherein the thrust nvPM emission index ratio is greater than or equal to 0.07 and preferably greater than or equal to 0.1 and more preferably greater than or equal to 0.

13.

5. 5 Gas turbine engine (10) according to any one of the preceding claims, wherein the thrust nvPM emission index ratio is greater than or equal to 0.178 and preferably greater than or equal to 0.2 and more preferably greater than or equal to 0.

223.

6. 6 Gas turbine engine (10) according to any one of the preceding claims, wherein the thrust nvPM emission index ratio is greater than or equal to 0.21 and preferably greater than or equal to 0.237 and more preferably greater than or equal to 0.

263.

7. 7 Gas turbine engine (10) according to any one of the preceding claims, wherein the thrust nvPM emission index ratio is less than or equal to 0.365 and preferably less than or equal to 0.335 and more preferably less than or equal to 0.

304.

8. 8 Gas turbine engine (10) according to any one of the preceding claims, wherein the nvPM emission index ratio of thrust is less than or equal to 0.317 and preferably less than or equal to 0.29 and more preferably less than or equal to 0.

264.

9. 9 Gas turbine engine (10) according to any one of the preceding claims, wherein: a) Fq is in the range of 204 kN to 420 kN and preferably is in the range of 229 kN to 385 kN and more preferably in the range of 255 kN to 350 kN; and / or b) Fra}enti is in the range of 14.2 kN to 29.4 kN and preferably is in the range of 16.0 kN to 26.9 kN and more preferably in the range of 17.8 kN to 24.5 kN.

10. 10 Gas turbine engine (10) according to any one of the preceding claims, wherein the ratio of the number of fuel spray nozzles (124) in the first subset (124A) of fuel spray nozzles (124) to the number of fuel spray nozzles (124) in the second subset (124B) of fuel spray nozzles (124) is in the range of 1:4 to 1:5, or preferably in the range of 1:4.25 to 1:4.

75.

11. 11 Gas turbine engine (10) according to any one of the preceding claims, wherein the combustor device (16) comprises one or more igniters (126).

12. 12 Gas turbine engine (10) according to claim 11, wherein each of the first subset (124A) of fuel spray nozzles (124) is located closer to one or more of the respective igniters (126) than the second subset (124B), and / or wherein one or more of the igniters (126) are arranged diametrically opposite another or more of the igniters (126).

13. 13 Gas turbine engine (10) according to any one of the preceding claims, wherein the fuel supplied to the combustor device (16) comprises a % of SAF in the range of 50% to 100%, preferably in the range of 70% to 100%, and more preferably in the range of 90% to 100%.

14. 14 Method (1000) of operating the gas turbine engine (10) according to any one of the preceding claims, the method comprising supplying (1002) fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles (124).

15. 15 Method (1000) of operating a gas turbine engine (10), the gas turbine engine (10) comprising: a combustor device (16), comprising a combustion chamber (120) and a plurality of fuel spray nozzles (124) designed to inject fuel into the combustion chamber (120), wherein the plurality of fuel spray nozzles (124) comprises a first subset (124A) of fuel spray nozzles (124) and a second subset (124B) of fuel spray nozzles (124), wherein the combustor device (16) can operate under a condition in which each of the fuel spray nozzles of the first subset (124A) of fuel spray nozzles (124) is supplied with fuel at a higher fuel flow rate than each of the fuel spray nozzles of the second subset (124B) of fuel spray nozzles (124),wherein a ratio of the number of fuel spray nozzles (124) in the first subset (124A) of fuel spray nozzles (124) to the number of fuel spray nozzles (124) in the second subset (124B) of fuel spray nozzles (124) is in the range of 1:3 to 1:6; and wherein: a thrust nvPM emission index ratio is defined as: [Math 280] niaxTo / pf^l'l • ________ / rntaxTO <J U . ralenti / P ,. / x idled £4aienti is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine (10) if it operates at approximately 7% of the available thrust under given operating conditions; and ^maxTo is the system loss-corrected nvPM emission index in mg / kg of the gas turbine engine (10) if it operates at approximately 100% of the available thrust under given operating conditions; F maxT O is the thrust of the gas turbine engine (10) at approximately 100% of the available thrust in kN under given operating conditions, F idle is Gas turbine engine thrust (10) at approximately 7% of the available thrust in kN under the given operating conditions; and the nvPM thrust emission index ratio is greater than 0.02; and the process includes supplying (1002) fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles (124).

Images