Fuel system for an aircraft engine

Abstract

A turbine engine for an aircraft includes a gas turbine engine having a fuel system that provides fuel to a combustion section. The fuel system includes a variable displacement pump driven by an accessory gearbox powered by a shaft of a gas turbine engine. The variable displacement pump has an inlet side and an outlet side. The variable displacement pump includes an actuator configured to adjust a discharge flow rate of the variable displacement pump. The fuel system also includes a fuel metering valve configured to receive the pressurized fuel from the variable displacement pump and control a flow rate of the pressurized fuel to the combustion section. The fuel system further includes a bypass valve fluidly coupling the outlet side and the inlet side of the variable displacement pump to direct excess of the pressurized fuel at the outlet side back to the inlet side.

Description

Technical Field

[0001] The present disclosure relates generally to aircraft engines and, more particularly, to fuel systems for aircraft engines. Background Art

[0002] An aircraft engine (e.g., a turbofan engine, a turboprop engine, etc.) includes a gas turbine engine (sometimes referred to as an engine core) and a fuel system that provides a constant flow of fuel to the combustion section of the gas turbine engine. The fuel system includes one or more pumps driven by a drive shaft of the gas turbine engine. The pump increases the pressure of the fuel to ensure adequate fuel flow rate to the combustion section of the gas turbine engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] A full and enabling disclosure of the presently described technology, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0004] Figure 1 is a schematic cross-sectional view of an example turbine engine for an aircraft in which examples disclosed herein may be implemented.

[0005] Figure 2 Yes, you can Figure 1 Schematic diagram of an example first fuel system implemented on an example turbine engine.

[0006] Figure 3 Is Figure 1 Schematic diagram of an example accessory gearbox driven by an example turbine engine and used to power an example boost pump and an example variable displacement pump of a first fuel system.

[0007] Figure 4 Yes, you can Figure 1 Schematic diagram of an example secondary fuel system implemented on an example turbine engine.

[0008] Figure 5 Yes, you can Figure 1 Schematic diagram of an example third fuel system implemented on an example turbine engine of FIG.

[0009] Figure 6 Yes, you can Figure 1 Schematic diagram of an example fourth fuel system implemented on an example turbine engine of FIG.

[0010] Figure 7 Yes, you can Figure 1 Schematic diagram of an example fifth fuel system implemented on an example turbine engine of FIG.

[0011] Figure 8Yes, you can Figure 1 Schematic diagram of an example sixth fuel system implemented on an example turbine engine of FIG.

[0012] Fig. 9 is a flow diagram representative of example machine-readable instructions and / or example operations that may be executed, instantiated, and / or performed by example programmable circuitry to implement an example fuel system controller for operating any of the example fuel systems disclosed herein.

[0013] Fig.10 is a block diagram of an example processing platform including programmable circuitry structured to execute, instantiate, and / or perform Fig. 9 Example machine readable instructions and / or example operations to implement an example fuel system controller.

[0014] The drawings are not drawn to scale. Rather, the thickness of regions may be exaggerated in the drawings. Generally, the same reference numerals will be used throughout the drawings and accompanying written description to refer to the same or similar parts. DETAILED DESCRIPTION

[0015] Reference will now be made in detail to examples or embodiments of the presently described technology, one or more examples of which are shown in the accompanying drawings. Each example or embodiment is provided by explaining the presently described technology, rather than limiting the presently described technology. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the presently described technology without departing from the scope or spirit of the presently described technology. For example, a feature shown or described as part of an example or embodiment may be used together with another example or embodiment to produce yet another example or embodiment. Therefore, the presently described technology is intended to cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0016] The terms "upstream" and "downstream" refer to relative positions or directions of fluid flow between a fluid upstream position or source and a fluid downstream position or end position. For example, "upstream" refers to a position relatively closer to or in a direction toward a fluid upstream position or source, while "downstream" refers to a position relatively closer to or in a direction toward a fluid downstream position or end position. As used herein, the terms "axial" and "longitudinal" both refer to directions parallel to a centerline axis of a gas turbine engine (e.g., a turboprop engine, a core gas turbine engine, etc.), while "radial" refers to directions perpendicular to the axial direction, and "tangential" or "circumferential" refers to directions perpendicular to the axial direction and the radial direction. Thus, as used herein, "radially inward" refers to a relative position or direction along a radial line from the periphery of the gas turbine engine toward the centerline axis of the gas turbine engine, and "radially outward" refers to a relative position or direction along a radial line from the centerline axis of the gas turbine engine toward the periphery of the gas turbine engine.

[0017] "Include" and "comprising" (and all their forms and tenses) are used as open-ended terms herein. Thus, whenever a claim adopts any form of "include" or "comprising" (e.g., includes, comprises, has, etc.) as a preamble or in any type of claim statement, it should be understood that additional elements, terms, etc. may be present without exceeding the scope of the corresponding claim or statement.

[0018] As used herein, the phrase "at least" when used as a transitional term, such as in the preamble of a claim, is open ended in the same manner as the terms "comprising" and "including" are open ended. The term "and / or," when used, for example, in a form such as A, B, and / or C, refers to any combination or subset of A, B, C, such as (1) A alone, (2) B alone, (3) C alone, (4) A and B, (5) A and C, (6) B and C, or (7) A and B and C. As used herein in the context of describing structures, components, items, objects, and / or things, the phrase "at least one of A and B" is intended to refer to embodiments that include any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing structures, components, items, objects, and / or things, the phrase "at least one of A or B" is intended to refer to embodiments that include any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. As used herein in the context of describing the performance or execution of processes, instructions, actions, activities, and / or steps, the phrase "at least one of A and B" is intended to refer to embodiments that include any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing the performance or execution of processes, instructions, actions, activities, and / or steps, the phrase "at least one of A or B" is intended to refer to embodiments that include any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B.

[0019] As used herein, singular references (e.g., "a", "a", "first", "second", etc.) do not exclude the plural. As used herein, the term "a" or "an" object refers to one or more of the object. The terms "a" (or "a"), "one or more", and "at least one" are used interchangeably herein. In addition, although listed separately, multiple devices, elements, or actions can be implemented by, for example, the same entity or object. In addition, although individual features may be included in different examples or claims, these may be combined, and the inclusion in different examples or claims does not mean that the combination of features is not feasible and / or disadvantageous.

[0020] As used herein, unless otherwise indicated, connection references (e.g., attached, coupled, connected, and joined) may include intermediate members between the elements referred to by the connection reference and / or relative movement between those elements. Thus, connection references do not necessarily infer that two elements are directly connected and / or are in fixed relation to each other.

[0021] Unless otherwise specifically stated, descriptors such as "first," "second," "third," etc., used herein do not confer or otherwise indicate any meaning of priority, physical order, arrangement in a list, and / or ordering in any manner, but are merely used as labels and / or arbitrary names to distinguish elements to facilitate understanding of the disclosed examples. In some examples, the descriptor "first" may be used to refer to an element in the detailed description, while a different descriptor (such as "second" or "third") may be used in the claims to refer to the same element. In such cases, it should be understood that such descriptors are only used to clearly identify those elements that may, for example, otherwise share the same name.

[0022] Turbine engines (e.g., turbofan engines, turboprop engines, etc.), such as those used on aircraft, include a fuel system that supplies a constant pressurized fuel flow to the combustion section of the engine. The fuel system generally includes a boost pump and a main pump arranged in series. The boost pump receives fuel from a fuel tank and increases the pressure of the fuel to a first pressure. The main pump receives fuel from the boost pump and further increases the pressure to a higher second pressure, and then supplies the fuel to the combustion chamber of the engine through a metering valve. This high-pressure fuel is also used as a hydraulic source for various valves and actuators on the engine and / or aircraft. The boost pump and the main pump are driven by an accessory gearbox, which is powered by the high-pressure shaft of the turbine engine. Therefore, the boost pump and the main pump are at a fixed speed ratio with the turbine engine. In other words, the speed of the boost pump and the main pump is directly related to the speed of the turbine engine.

[0023] Known fuel systems utilize fixed displacement as the main pump. Therefore, the output of the main pump is directly related to the speed of the turbine engine. The size and power of the main pump are usually designed to produce a fuel flow rate that is much higher than the pressure and flow requirements of the turbine engine to ensure that there is enough fuel supply during operation. In other words, the main pump is usually oversized for most operating conditions. Therefore, under some operating conditions, the main pump will overproduce pressurized fuel. Therefore, a portion of the pressurized fuel is circulated back to the inlet side of the main pump through the bypass valve. As a result, the bypass portion of the discharge flow from the main pump is pressurized and decompressed, but there is no useful work, so the power extracted from the engine has a negative impact on the overall engine efficiency. This also produces waste heat that increases the temperature of the fuel.

[0024] Fuel systems are designed to withstand certain temperatures. Higher temperature fuels can lacquer and form coke along fuel lines and devices, which can have a negative impact on various fuel lines and devices (e.g., plugging devices). In addition, as described above, some known systems include a recirculation flow back to the fuel tank. Therefore, the heated fuel returns to the fuel tank, which results in a high fuel tank startup temperature. This can reduce the performance of the fuel-oil thermal management system (FOTMS) and the vehicle thermal management (VTMS). Therefore, this increased heat is undesirable during certain power modes. Some known systems attempt to solve this problem by adding additional coolers or coolers to reduce the temperature of the fuel. These systems are expensive, complex, and add considerable weight to the entire engine.

[0025] An example fuel system for an aircraft turbine engine is disclosed herein, and the example fuel system includes a variable displacement pump as the main pump of the fuel system. A variable displacement pump is a pump whose stroke of a pumping member can be changed. For example, a variable displacement pump can be implemented as a variable displacement vane pump or a variable displacement piston pump. This enables the discharge flow rate and / or pressure output to be changed independently of the input shaft speed. Therefore, the discharge flow rate and / or pressure output of the variable displacement pump can be changed independently of the speed of the turbine engine. Therefore, the stroke of the variable displacement pump can be changed (e.g., reduced) to reduce (e.g., minimize) the excess flow under various operating conditions. For example, the variable displacement pump can be controlled to produce pressurized fuel under or closer to the needs of the combustion section and the actuator device. This reduces the power consumption or extraction of the engine. Therefore, the example fuel system disclosed herein improves the overall efficiency of the engine. In addition, by reducing the excess flow, the example fuel system reduces (e.g., minimizes) waste heat, thereby reducing or preventing varnishing and coke formation, and eliminating or reducing the need for a chiller or cooler.

[0026] Now referring to the accompanying drawings, Figure 1 1 is a schematic cross-sectional view of an example turbine engine 100 that may be combined with various examples disclosed herein. Example turbine engine 100 may be implemented on an aircraft and is therefore referred to as an aircraft engine. In this example, turbine engine 100 is a turbofan-type engine. However, the principles of the present disclosure are also applicable to other types of engines, such as turboprop engines and engines without a nacelle, such as unducted fan (UDF) engines (sometimes referred to as propfan engines). In addition, the example principles disclosed herein may be implemented on other types of engines, such as non-aircraft engines.

[0027] like Figure 1As shown, the turbine engine 100 includes an outer bypass duct 102 (which may also be referred to as a nacelle, a fan duct, or a casing), a gas turbine engine 104 (which may also be referred to as a core turbine engine), and a fan section 106. The gas turbine engine 104 and the fan section 106 are at least partially disposed in the outer bypass duct 102. The gas turbine engine 104 is disposed downstream of the fan section 106 and drives the fan section 106 to generate forward thrust.

[0028] like Figure 1 As shown, turbine engine 100 and / or gas turbine engine 104 defines a longitudinal or axial centerline axis 108 extending therethrough for reference. Figure 1 Also included are annotated directional diagrams that reference axial direction A, radial direction R, and circumferential direction C. Generally, as used herein, axial direction A is a direction extending generally parallel to centerline axis 108, radial direction R is a direction extending orthogonally outward from centerline axis 108 or orthogonally inward toward centerline axis 108, and circumferential direction C is a direction extending concentrically around centerline axis 108. Additionally, as used herein, the term “forward” refers to a direction along centerline axis 108 in the direction of movement of turbine engine 100, such as Figure 1 , and the term "rearward" refers to a direction along the centerline axis 108 in a relative direction, such as Figure 1 on the right side of the screen.

[0029] The gas turbine engine 104 includes a substantially tubular outer casing 110 (which may also be referred to as a mid-casing) defining an annular inlet 112. The outer casing 110 of the gas turbine engine 104 may be formed by a single casing or multiple casings. The outer casing 110 encloses, in serial flow relationship: a compressor section having a supercharger or low-pressure compressor 114 ("LP compressor 114") and a high-pressure compressor 116 ("HP compressor 116"); a combustion section 118; a turbine section having a high-pressure turbine 120 ("HP turbine 120") and a low-pressure turbine 122 ("LP turbine 122"); and an exhaust section 124.

[0030] Gas turbine engine 104 includes a high pressure shaft 126 (“HP shaft 126 ”) drivingly coupling HP turbine 120 and HP compressor 116 . Gas turbine engine 104 also includes a low pressure shaft 128 (“LP shaft 128 ”) drivingly coupling LP turbine 122 and LP compressor 114 . LP shaft 128 is also coupled to fan shaft 130 .

[0031] The fan section 106 includes a plurality of fan blades 132 that are coupled to the fan shaft 130 and extend radially outward from the fan shaft 130. In some examples, the LP shaft 128 can be directly coupled to the fan shaft 130 (i.e., a direct drive configuration). In an alternative configuration, the LP shaft 128 can be coupled to the fan shaft 130 via a reduction gear 134 (e.g., an indirect drive or gear transmission configuration). Although the gas turbine engine 104 includes two compressors and two turbines in this example, in other examples, the gas turbine engine 104 may include only one compressor and one turbine. In addition, in other examples, the gas turbine engine 104 may include more than two compressors and turbines. In such an example, the gas turbine engine 104 may include more than two drive shafts or spools.

[0032] like Figure 1 As shown, during operation of turbine engine 100, air 136 enters an inlet portion 138 of turbine engine 100. Air 136 is accelerated by fan blades 132 (sometimes considered a low-pressure compressor). A first portion 140 of air 136 flows into a bypass airflow passage 142, while a second portion 144 of air 136 flows into the inlet 112 of gas turbine engine 104 (and, therefore, into LP compressor 114). One or more sequential stages of LP compressor rotor blades 148 and LP compressor stator vanes 146 coupled to LP shaft 128 progressively compress the second portion 144 of air 136 flowing through LP compressor 114 on the way to HP compressor 116. Next, one or more sequential stages of HP compressor rotor blades 152 and HP compressor stator vanes 150 coupled to HP shaft 126 further compress the second portion 144 of air 136 flowing through HP compressor 116. This provides compressed air 154 to the combustion section 118 where it is mixed with fuel and combusted to provide combustion gases 156. The fuel is injected into the combustion section 118 through one or more nozzles 157. The turbine engine 100 includes a fuel system to provide pressurized fuel to the combustion section 118 of the gas turbine engine 104 through the nozzles 157. Example fuel systems are disclosed in further detail herein.

[0033] The combustion gases 156 flow through the HP turbine 120, wherein one or more sequential stages of HP turbine rotor blades 160 and HP turbine stator vanes 158 coupled to the HP shaft 126 extract a first portion of kinetic and / or thermal energy. This energy extraction supports the operation of the HP compressor 116. The combustion gases 156 then flow through the LP turbine 122, wherein one or more sequential stages of LP turbine rotor blades 164 and LP turbine stator vanes 162 coupled to the LP shaft 128 extract a second portion of thermal and / or kinetic energy from the combustion gases 156. This energy extraction causes the LP shaft 128 to rotate, which supports the operation of the LP compressor 114 and / or the rotation of the fan shaft 130. The combustion gases 156 then exit the gas turbine engine 104 through the exhaust section 124 of the gas turbine engine 104. The combustion gases 156 mix with the first portion 140 of the air 136 from the bypass air flow passage 142. The mixed gases exit an exhaust nozzle 170 (eg, a converging / diverging nozzle) of the bypass airflow passage 142 to generate propulsive thrust.

[0034] Figure 2 Can be combined Figure 1 Schematic diagram of an example first fuel system 200 implemented with an example turbine engine 100 of FIG. The first fuel system 200 is used to provide or supply fuel to the combustion section 118 of the gas turbine engine 104, and may also be used to support fuel to one or more other locations (e.g., devices, systems, etc.), as disclosed in further detail herein. Figure 2 In the schematic diagram of , solid lines represent fluid lines that enable fluid (e.g., fuel) to flow between two or more locations, while dashed lines represent hydraulic lines in which fluid (e.g., fuel) may be present but not necessarily flowing. Fluid lines and hydraulic lines may be implemented by any type of fluid connector (such as a hose, tube, connector, port, channel, and / or any other structure or opening that fluidically couples two or more components. Therefore, any two or more components having a solid or dashed line between them may be considered to be fluidically coupled.

[0035] In the example shown, the first fuel system 200 includes a fuel tank 202 that stores fuel (e.g., Jet A, Jet A1, kerosene, etc.). In some examples, the fuel tank 202 is located in one or both of the wings of the aircraft. In other examples, the fuel tank 202 can be provided in another location on the aircraft (e.g., in the fuselage).

[0036] In the illustrated example, the first fuel system 200 includes a boost pump 204 and a variable displacement pump 206 (e.g., a main pump) arranged in series. The boost pump 204 and the variable displacement pump 206 gradually or sequentially increase the pressure of the fuel to ensure that there is an adequate supply of fuel to the combustion section 118 of the turbine engine 100. The boost pump 204 and the variable displacement pump 206 are driven or powered by the gas turbine engine 104 of the turbine engine 100, as disclosed in further detail herein.

[0037] In the illustrated example, the first fuel system 200 includes a fuel metering valve (FMV) 208 between a variable displacement pump 206 and the combustion section 118. The FMV 208 receives pressurized fuel from the variable displacement pump 206. The FMV 208 controls the flow rate of the pressurized fuel to the combustion section 118. Therefore, the FMV 208 meters the fuel flow to the gas turbine engine 104. In this example, the FMV 208 is implemented as a sliding spool valve. However, in other examples, the FMV 208 can be implemented by another type of valve (e.g., a rotating spool valve). In the illustrated example, the fuel metering valve 208 is monitored or controlled by a linear variable differential transformer (LVDT) 210 and a servo valve 212. The servo valve 212 is fluidly coupled to the FMV 208 and controls the fluid flow to hydraulically operate the FMV 208. In other words, the position of the FMV 208 is controlled by the servo valve 212 (e.g., by controlling the hydraulic fluid entering / leaving the FMV 208). LVDT 210 provides feedback to a controller (eg, FMV controller 244 ) by measuring the position of FMV 208 .

[0038] like Figure 2 As shown, the first fuel system 200 includes a first fluid line 214 fluidly connecting the fuel tank 202 and the boost pump 204, a second fluid line 216 fluidly connecting the boost pump 204 and the variable displacement pump 206, a third fluid line 218 fluidly connecting the variable displacement pump 206 and the FMV 208, and a fourth fluid line 220 fluidly connecting the FMV 208 and the combustion section 118 of the gas turbine engine 104. The fluid lines 214-220 may include any number or configuration of fluid connections. The variable displacement pump 206 has an inlet side and an outlet side, the inlet side receiving fuel via the second fluid line 216, and the outlet side connected to the third fuel line 218 and delivering fuel thereto.

[0039] In operation, the boost pump 204 receives fuel from the fuel tank 202 and increases the pressure of the fuel to a first pressure, sometimes referred to as a priming pressure. The variable displacement pump 206 receives the fuel at the priming pressure from the boost pump 204 and further increases the pressure of the fuel to a desired or set pressure, which is higher than the pressure required by the gas turbine engine 104 and other devices to ensure sufficient fuel flow. For example, the boost pump 204 can increase the pressure to 200 pounds per square inch (psi), and the variable displacement pump 206 can further increase the pressure to 1000psi. In some examples, the size and gears of the boost pump 204 and the variable displacement pump 206 are designed to ensure that there is sufficient fuel supply based on a range of operating speeds. After the fuel is pressurized by the boost pump 204 and the variable displacement pump 206, the FMV 208 controls the fuel flow to the combustion section 118. For example, the FMV 208 can reduce the flow rate and / or pressure to an amount that achieves the desired speed of the gas turbine engine 104.

[0040] As described above, at least some of the pressurized fuel is directed to the gas turbine engine 104 of the turbine engine 100, where the pressurized fuel may be injected into the combustion section 118. Additionally, in some examples, some of the fuel may be used as a high pressure fluid source for one or more devices. Figure 2 As shown, the first fuel system 200 includes a fifth fluid line 222, which fluidly couples the third fluid line 218 (at the outlet of the variable displacement pump 206) to one or more actuators 224. The actuators 224 may include, for example, actuators for inlet guide vanes on the turbine engine 100 or variable area exhaust ports on the turbine engine 100. The pressurized fuel is used as a hydraulic power source to operate these actuators 224. Additionally or alternatively, the fuel can be used for other devices, such as valves, solenoids, etc. The fuel is then directed to the second fluid line 216 at the inlet or low pressure side of the variable displacement pump 206 through the fifth fluid line 222. Therefore, the fuel used by the actuator 224 is recirculated back through the variable displacement pump 206.

[0041] As described above, the variable displacement pump 206 generates a pressure that is higher than the demand of the combustion section 118 and the actuator 224 to ensure that there is always an adequate supply of fuel. Figure 2In the example shown, the first fuel system 200 includes a sixth fluid line 226 (which may also be referred to as a bypass fluid line) having a bypass valve 228 that fluidly couples the third fluid line 218 and the second fluid line 216. The bypass valve 228 fluidly couples the outlet side of the variable displacement pump 206 and the inlet side of the variable displacement pump 206. This enables the bypass valve 228 to direct an excess portion of the pressurized fuel at the outlet side of the variable displacement pump 206 back to the inlet side of the variable displacement pump 206. The bypass valve 228 controls the amount of fuel available to the combustion section 118 and the actuator 224. In some examples, the bypass valve 228 is configured to operate based on a pressure differential across the FMV 208 (e.g., control the amount of pressurized fuel directed from the outlet side to the inlet side). For example, in Figure 2 In the example shown, the first fuel system 200 includes a hydraulic line 230 (which may also be referred to as a sense line) that fluidly couples a bypass valve 228 and the fourth fluid line 220 (and, therefore, the outlet side of the FMV 208). Thus, the bypass valve is hydraulically connected to the fuel pressure on both sides of the FMV 208. The bypass valve 228 is configured to maintain a nominal or fixed pressure drop of the fuel across the FMV 208. In other words, by controlling the excess fuel flow through the bypass valve 228, the bypass valve 228 controls the amount of fuel available at the FMV 208. Thus, when the FMV 208 changes the flow rate, the bypass valve 228 operates (e.g., opens or closes) to adjust the flow rate of the portion of the fuel sent to the FMV 208. In some examples, the bypass valve 228 does not require any electrical actuation. Instead, the bypass valve 228 is hydraulically mechanically controlled and automatically adjusts its position based on the pressure drop across the FMV 208. For example, the bypass valve 228 is fluidly coupled to pressures upstream and downstream of the FMV 208 (e.g., via the sixth fluid line 226 and the hydraulic line 230). These pressures acting on the area of ​​the FMV 208 and the spring force in the bypass valve 228 are resolved as a force balance on a valve member (e.g., a sliding spool) in the bypass valve 228. The bypass valve 228 is configured to be in equilibrium at a fixed pressure differential (dP) across the FMV 208 (e.g., 30-100 psi pressure drop / pressure differential (psid)). Therefore, when the FMV 208 is stroked open / closed, the dP across the FMV 208 begins to change, and the stroke position of the bypass valve 228 automatically changes to achieve balance. This changes the bypass flow rate through the sixth fluid line 226, thereby achieving a set point flow through the FMV 208. However, in other examples, the bypass valve 228 can be an electronically controlled valve.

[0042] exist Figure 2In the example shown, the first fuel system 200 includes a seventh fluid line 232 having a relief valve 234, which fluidically couples the third fluid line 218 and the second fluid line 216. The relief valve 234 can be implemented as a one-way valve or a check valve. The relief valve 234 is used as a backup or redundant relief valve device. For example, the relief valve 234 can be set to a relatively high pressure threshold (e.g., 2500 psi). If the pressure at the outlet of the variable displacement pump 206 reaches the threshold, the relief valve 234 opens to discharge the high-pressure fluid back to the inlet of the variable displacement pump 206.

[0043] As described above, the boost pump 204 and the variable displacement pump 206 are driven by the gas turbine engine 104 of the turbine engine 100. For example, referring to Figure 3 , the turbine engine 100 includes an accessory gearbox 300. The accessory gearbox 300 is driven or powered by a shaft 302 that meshes with and is driven by the HP shaft 126 of the gas turbine engine 104. For example, the shaft 302 may mesh with the HP shaft 126 via a bevel gear 304. Thus, the accessory gearbox 300 is powered by the HP shaft 126 of the gas turbine engine 104. In other examples, the accessory gearbox 300 may be powered or driven by the LP shaft 128 of the gas turbine engine 104.

[0044] The accessory gearbox 300 may provide power to one or more devices. The accessory gearbox 300 may have one or more output shafts to drive one or more accessories or devices, such as pumps, generators, etc. In this example, the boost pump 204 and the variable displacement pump 206 are driven by the accessory gearbox 300. For example, a first shaft 306 from the accessory gearbox 300 drives the boost pump 204, and a second shaft 308 from the accessory gearbox 300 drives the variable displacement pump 206. In other examples, the boost pump 204 and the variable displacement pump 206 may be driven by the same shaft from the accessory gearbox 300. The accessory gearbox 300 provides a fixed gear ratio between the gas turbine engine 104 and the boost pump 204 and the variable displacement pump 206. Therefore, the boost pump 204 and the variable displacement pump 206 are driven by the gas turbine engine 104.

[0045] Boost pump 204 may be driven by turbine engine 100 at a fixed speed ratio. Therefore, the speed of turbine engine 100 directly affects the output rate and pressure of boost pump 204. However, pump 206 is implemented as a variable displacement pump. This means that the displacement of a piston or other component of variable displacement pump 206 can be changed, thereby affecting (e.g., increasing or decreasing) the discharge flow rate and / or pressure of variable displacement pump 206. Figure 2 and Figure 3As shown, the variable displacement pump 206 includes an actuator 236 (which may also be referred to as a pump actuator). The actuator 236 is used to adjust the discharge flow rate and / or pressure of the variable displacement pump 206. In particular, the actuator 236 can be activated to change the displacement of the piston or other components in the variable displacement pump 206. Therefore, when the variable displacement pump 206 is still mechanically driven by the gas turbine engine 104, the output flow rate and / or pressure of the variable displacement pump 206 can be changed independently of the speed of the gas turbine engine 104. In some examples, the variable displacement pump 206 is implemented as a variable displacement vane pump or a variable displacement piston pump. In other examples, the variable displacement pump 206 can be implemented as another type of variable displacement pump.

[0046] There are many advantages to using a variable displacement pump. For example, the discharge flow rate and / or pressure of the variable displacement pump 206 can be controlled to reduce (e.g., minimize) the excess fuel flow through the bypass valve 228. Therefore, the variable displacement pump 206 does not continuously overproduce fuel flow as a known fuel system with a fixed displacement pump. This also reduces (e.g., minimizes) the power draw of the gas turbine engine 104, thereby improving the efficiency of the turbine engine 100. This also reduces (e.g., minimizes) the temperature rise of the fuel and helps to improve the thermal synchronization capability. Therefore, the use of the first fuel system 200 eliminates or reduces the need for a chiller or cooler as seen in a known system. For example, a smaller air / oil heat exchanger can be used, which reduces the weight of the entire system. The actuator 236 can control the discharge flow rate and / or pressure of the variable displacement pump 206 based on one or more parameters and / or commands. For example, in some examples, the actuator 236 is configured to adjust the discharge flow rate and / or pressure of the variable displacement pump based on the outlet pressure of the FMV. In other examples, actuator 236 may adjust the exhaust flow rate and / or pressure based on one or more other parameters (eg, temperature, velocity, etc.).

[0047] Although the boost pump 204 is driven by the gas turbine engine 104 via the accessory gearbox 300 in this example, in other examples, the boost pump 204 may be driven by an electric motor or other device. The boost pump 204 is located upstream of the variable displacement pump 206. In some examples, the first fuel system 200 may include more than one pump upstream of the variable displacement pump 206. In other examples, the first fuel system 200 may not include a boost pump. Instead, the first fuel system 200 may only include the variable displacement pump 206.

[0048] exist Figure 2In the example shown, the first fuel system 200 includes a controller 238 (e.g., a fuel system controller) that operates various devices and controls the operation of the first fuel system 200. The controller 238 is communicatively coupled to one or more sensors (disclosed in further detail below), an actuator 236 of the variable displacement pump 206, valves 212, 228, and / or any other device that controls and / or monitors various parameters of the first fuel system 200. Figure 2 The controller 238 may be instantiated (e.g., created an instance, generated for any length of time, embodied, implemented, etc.) by a programmable circuit, such as a central processing unit (CPU) that executes the first instruction. Additionally or alternatively, the controller 238 may be instantiated (e.g., created an instance, generated for any length of time, embodied, implemented, etc.) by (i) an application specific integrated circuit (ASIC) and / or (ii) a field programmable gate array (FPGA) that is structured and / or constructed to perform operations corresponding to the first instruction in response to the execution of the second instruction. It should be understood that Figure 2 Some or all of the circuits may therefore be instantiated at the same or different times. Figure 2 Some or all of the circuits of can be instantiated, for example, in one or more threads that execute concurrently on hardware and / or serially on hardware. Furthermore, in some examples, Figure 2 Some or all of the circuits may be implemented by microprocessor circuits executing instructions and / or FPGA circuits performing operations to implement one or more virtual machines and / or containers.

[0049] exist Figure 2 In the example shown, the controller 238 includes an input / output module 240, a comparator 242, a FMV controller 244, a pump actuator controller 246, and a bypass valve controller 248. The input / output module 240 receives signals from one or more sensors that measure one or more parameters or parameter values ​​of the first fuel system 200 and / or the gas turbine engine 104. The comparator 242 compares the measured value of the parameter with one or more thresholds or threshold ranges. Based on whether the parameter meets the threshold or threshold range, the controllers 244, 246, 248 can operate one or more of the devices to control fuel pressurization and / or flow rate. The input / output module 240 can also receive signals or commands from other devices, such as pilot commands.

[0050] The FMV controller 244 controls the FMV 208. In particular, the FMV controller 244 controls the servo valve 212, which controls the position of the FMV 208 to affect the fuel flow rate to the gas turbine engine 104. The FMV controller 244 receives feedback measurements from the LVDT 210. The FMV controller 244 may control the servo valve 212 based on one or more signals from a pilot, such as from a thrust lever or a throttle lever in a cockpit. For example, based on the position of the thrust lever, the FMV 208 operates to supply more or less fuel to the combustion section 118 to achieve a desired thrust level.

[0051] The pump actuator controller 246 controls the actuator 236 to affect the stroke of the variable displacement pump 206, thereby affecting the discharge flow rate and / or pressure of the variable displacement pump 206. In some examples, the pump actuator controller 246 is implemented by or communicates with a full authority digital engine control (FADEC) (sometimes also referred to as an engine control unit or electronic engine controller). The FADEC determines or sets a target pump flow discharge rate and / or pressure, and the pump actuator controller 246 operates the actuator 236 to set the variable displacement pump 206 so as to achieve or meet the target pump flow discharge rate. In some examples, the actuator 236 is a hydraulically driven actuator. For example, the actuator 236 can be powered by pressurized fuel. For example, as Figure 2 As shown, the eighth fluid line 250 fluidly connects (e.g., outputs) the high-pressure fluid from the third fluid line 218 to the actuator 236, and the ninth fluid line 251 fluidly connects the low-pressure fluid from the second fluid line 216 to the actuator 236. In particular, in this example, the actuator 236 includes a servo valve 252, which is fluidly coupled to the outlet side of the variable displacement pump 206 via the eighth fluid line 250 and is fluidly coupled to the inlet side of the variable displacement pump via the ninth fluid line 251. The actuator 236 and the servo valve 252 operate based on the pressure difference on the inlet side and the outlet side of the variable displacement pump 206. For example, the pump actuator controller 246 operates the servo valve 252 to control the flow of pressurized fuel (output by the variable displacement pump 206) into the actuator 236 and control the position of the actuator 236. In other examples, the actuator 236 can be an electrically driven actuator. For example, the actuator 236 may include a motor or a solenoid that operates to control the position of the actuator 236. Thus, in some examples, the pump actuator controller 246 may operate the actuator 236 by controlling the voltage applied to the actuator 236.

[0052] As described above, the first fuel system 200 may include one or more sensors (e.g., pressure sensors, flow sensors, temperature sensors, speed sensors, etc.) to measure and / or monitor one or more parameters of the first fuel system 100 and / or the gas turbine engine 104. The pump actuator controller 246 may control the actuator 236 based on one or more of the measured parameters. In some examples, the comparator 242 compares the parameter to one or more thresholds. For example, if the parameter meets (e.g., exceeds) the threshold, the pump actuator controller 246 may activate the actuator 236 to change (e.g., increase or decrease) the discharge rate of the variable displacement pump.

[0053] For example, the parameter may include the speed of the gas turbine engine 104. Figure 2 As shown, the first fuel system 200 includes a speed sensor 254 for measuring the speed of the gas turbine engine 104. The speed may correspond to the LP shaft 128 ( Figure 1 ) or HP shaft 126( Figure 1 ). The input / output module 240 receives the speed measurement from the speed sensor 254, and the comparator 242 can compare the speed to one or more speed thresholds or ranges. Depending on the speed of the gas turbine engine 104, the pump actuator controller 246 controls the actuator 236 to change the stroke of the variable displacement pump 206, thereby changing the flow discharge rate and / or pressure.

[0054] As another example, the parameter may include pressure or pressure differential at one or more locations of the first fuel system 200. For example, Figure 2 The first fuel system 200 includes sensors 256, 258 at the inlet and outlet of the FMV 208. The sensors 256, 258 may be pressure sensors. The comparator 242 may compare the pressure and / or the pressure difference with one or more threshold values ​​or threshold ranges. Based on the comparison, the pump actuator controller 246 may control the actuator 236 to change the stroke of the variable displacement pump 206. As another example, the parameter may include the temperature of the fuel at one or more locations of the first fuel system 200. For example, the sensors 254, 256 may be temperature sensors. The pump actuator controller 246 may control the actuator 236 based on the temperature and / or the temperature difference to change the discharge rate and / or pressure of the variable displacement pump 206. The first fuel system 200 may include more or fewer sensors, and / or the sensors may be placed at other locations and / or measure other parameters. In some examples, the controller 238 may measure or monitor multiple parameters simultaneously. The controller 238 may use one or more of these parameters to determine how to adjust the discharge rate and / or pressure of the variable displacement pump.

[0055] In some examples, bypass valve 228 is an electronically controlled valve. In such examples, bypass valve controller 248 can control the state of the valve. For example, bypass valve 228 can operate between an open state and a closed state (and / or any state between the open state and the closed state (e.g., half-open)). Bypass valve controller 248 can control bypass valve 228 based on one or more sensor parameters (e.g., pressure, temperature, etc.) and / or signals from other devices (e.g., controls in the cockpit). For example, bypass valve controller 248 can operate bypass valve 228 based on a pressure differential across FMV 208 (e.g., measured by sensors 256, 258).

[0056] Figure 4 is a schematic diagram of an example second fuel system 400 that may be implemented in conjunction with turbine engine 100. The second fuel system 400 will not be described in detail below. Figure 2 The components of the disclosed first fuel system 200 are substantially similar or identical, and those components having structures and / or functions substantially similar or identical to the structures and / or functions of the components of the first fuel system 200. Instead, the interested reader is referred to the corresponding description above. To facilitate this processing, the same reference numerals are used for similar structures.

[0057] Figure 4 The second fuel system 400 has Figure 2 The components and functions of the first fuel system 200 are similar. However, in Figure 4 In the second fuel system 400, the sixth fluid pipeline 226 ( Figure 2 ) and actuator 224 ( Figure 2 ) has been removed. Thus, in this example, the second fuel system 400 does not provide pressurized fuel to those additional actuators or devices. In this example, the pressurized fuel produced by the variable displacement pump 206 is directed only to the combustion section 118 and / or the bypass valve 228 (and / or in the event of overpressure, to the bleed valve 234). The controller 238 can operate substantially the same as disclosed in conjunction with the first fuel system 200 to operate the devices of the second fuel system 400 and control the flow rate and / or pressure of the fuel.

[0058] Figure 5 is a schematic diagram of an example third fuel system 500 that may be implemented in conjunction with turbine engine 100. The third fuel system 500 will not be described in detail below. Figure 2 and Figure 4The components of the disclosed first fuel system 200 and / or second fuel system 400 are substantially similar or identical, and those components having structures and / or functions substantially similar or identical to the structures and / or functions of the components of the first fuel system 200 and / or second fuel system 400. Instead, the interested reader is referred to the corresponding description above. To facilitate this processing, the same reference numerals are used for similar structures.

[0059] Figure 5 The third fuel system 500 includes a compensating valve 502, which is used to improve the accuracy of the position of the bypass valve 228, thereby improving the metering accuracy of the fuel flow through the FMV 208. Generally, the bypass valve 228 is configured to maintain a fixed pressure drop (e.g., 30-100 psid) on the FMV 208. The bypass valve 228 can be a conventional valve including a flow control member (e.g., a plug, a piston, a rotating sleeve, a plate, etc.). The flow control member moves to a specific position to adjust the flow through the bypass valve 228, which affects the pressure drop on the FMV 208, thereby maintaining a fixed pressure drop on the FMV 208. However, the movement of the flow control member is not perfect and may be affected by the size of the valve and / or the spring stiffness. Therefore, the compensating valve 502 helps to fine-tune the bypass valve position and improve the steady-state accuracy of the FMV 208.

[0060] For example, Figure 5 As shown, the third fuel system 500 includes a first hydraulic line 504 fluidly coupling the third fluid line 218 and the compensating valve 502, and a second hydraulic line 506 fluidly coupling the fourth fluid line 220 and the compensating valve 502. Therefore, the compensating valve 502 can sense or measure the pressure difference across the FMV 208. The third fuel system 500 includes a third hydraulic line 508 fluidly coupling the compensating valve 502 and the bypass valve 228. Based on the pressure difference across the FMV 208, the compensating valve 502 can adjust the pressure in the third hydraulic line 508, which adjusts the force margin on the bypass valve 228. This improves the accuracy of the metering system by compensating for the pressure drop across the bypass valve 228. In particular, the ability of the bypass valve 228 to maintain a fixed dP across the FMV 208 is affected by factors such as fluid temperature, spring linearity, and manufacturing tolerances. Therefore, the compensating valve 502 improves the variation around the nominal pressure value by taking these factors into account, thereby making the metered fuel output to the combustion section 118 more accurate.

[0061] The controller 238 may operate substantially the same as disclosed in connection with the first fuel system 200 to operate the devices of the third fuel system 500 and control the flow rate and / or pressure of the fuel. Figure 5 In the embodiment, the third fuel system 500 does not provide any fuel to the actuator 224 ( Figure 2) provides pressurized fuel. However, in other examples, the third fuel system 500 can provide pressurized fuel to the actuator 224, similar to Figure 2 The first fuel system 200 in.

[0062] Figure 6 is a schematic diagram of an example fourth fuel system 600 that may be implemented in conjunction with turbine engine 100. The fourth fuel system 600 will not be described in detail below. Figure 2 , Figure 4 and Figure 5 The components of the disclosed first fuel system 200, second fuel system 400, and / or third fuel system 500 are substantially similar or identical, and those components having structures and / or functions substantially similar or identical to the structures and / or functions of the components of the first fuel system 200, second fuel system 400, and / or third fuel system 500. Instead, the interested reader is referred to the corresponding description above. To facilitate this processing, the same reference numerals are used for similar structures.

[0063] exist Figure 6 In the example shown, the fourth fuel system 600 does not include Figure 2 , Figure 4 and Figure 5 Bypass valve in fuel system 200, 400, 500. Figure 6 As shown, the fourth fuel system 600 includes a throttle valve 602. The throttle valve 602 is coupled to and / or otherwise integrated with the fourth fluid line 220. Thus, the throttle valve 602 is fluidly coupled between the FMV 208 and the combustion section 118 of the gas turbine engine 104. The throttle valve 602 operates to reduce the pressure of the fuel before the combustion section 118 and maintain a fixed pressure drop across the FMV 208. For example, the fourth fuel system 600 includes a hydraulic line 604 that fluidly couples the throttle valve 602 and the third fluid line 218 (and therefore, the inlet side of the FMV 208). Thus, the throttle valve 602 can sense or measure a pressure differential across the FMV 208. The throttle valve 602 is configured to operate (e.g., adjust itself, open, close, move to a position between open and closed) based on the pressure differential across the FMV 208 to maintain a fixed pressure drop across the FMV 208. In other words, the throttle valve 602 can be adjusted to absorb any pressure differential left in the system. In some examples, the throttle valve 602 is implemented as a sliding spool valve. However, in other examples, the throttle valve 602 can be implemented by other types of valves. In some examples, similar to the bypass valve 228 ( Figure 2), throttle valve 602 is hydraulically mechanically operated and automatically adjusts its position based on the dP at FMV 208. In other examples, throttle valve 602 is electrically operated, such as by bypass valve controller 248. In some examples, bypass valve controller 248 can control throttle valve 602 based on one or more parameters (e.g., measured dP at FMV 208).

[0064] The controller 238 may operate substantially the same as disclosed in connection with the first fuel system 200 to operate the devices of the fourth fuel system 600 and control the flow rate and / or pressure of the fuel. Figure 6 , the fourth fuel system 600 does not provide power to the actuator 224 ( Figure 2 ) provides pressurized fuel. However, in other examples, the fourth fuel system 600 can provide pressurized fuel to the actuator 224, similar to Figure 2 The first fuel system 200 in.

[0065] Figure 7 is a schematic diagram of an example fifth fuel system 700 that may be implemented in conjunction with turbine engine 100. The fifth fuel system 700 will not be described in detail below. Figure 2 , Figure 4 , Figure 5 and Figure 6 The components of the disclosed first fuel system 200, second fuel system 400, third fuel system 500 and / or fourth fuel system 600 are substantially similar or identical, and those components having structures and / or functions substantially similar or identical to the structures and / or functions of the components of the first fuel system 200, second fuel system 400, third fuel system 500 and / or fourth fuel system 600. Instead, the interested reader is referred to the corresponding description above. To facilitate this processing, the same reference numerals are used for similar structures.

[0066] Figure 7 The fifth fuel system 700 is similar to Figure 6 The fourth fuel system 600 further includes a compensating valve 702. The compensating valve 702 is connected to Figure 5 The compensating valve 502 of FIG. 208 operates similarly to improve the metering accuracy of the fuel flow through the FMV 208. For example, Figure 7As shown, the fifth fuel system 700 includes a first hydraulic line 704 fluidly coupling the third fluid line 218 and the compensating valve 702, and a second hydraulic line 706 fluidly coupled between the fourth fluid line 220 and the compensating valve 702. Thus, the compensating valve 702 can sense or measure the pressure differential across the FMV 208. The fifth fuel system 700 includes a third hydraulic line 708 fluidly coupling the compensating valve 702 and the throttle valve 602. Based on the pressure differential across the FMV 208, the compensating valve 702 can adjust the pressure in the third hydraulic line 708, which adjusts the force margin on the throttle valve 602. This compensation based on the pressure differential improves the accuracy of the metering system by compensating for the pressure drop across the throttle valve 602. Therefore, the compensating valve 702 improves the variation around the nominal pressure value, so that the metered fuel output to the combustion section 118 is more accurate.

[0067] The controller 238 may operate substantially the same as disclosed in connection with the first fuel system 200 to operate the devices of the fifth fuel system 700 and control the flow rate and / or pressure of the fuel. Figure 7 , the fifth fuel system 700 does not provide power to the actuator 224 ( Figure 2 ) provides pressurized fuel. However, in other examples, the fifth fuel system 700 can provide pressurized fuel to the actuator 224, similar to Figure 2 The first fuel system 200 in.

[0068] Figure 8 is a schematic diagram of an example sixth fuel system 800 that may be implemented in conjunction with turbine engine 100. The sixth fuel system 800 will not be described in detail below. Figure 2 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The components of the disclosed first fuel system 200, second fuel system 400, third fuel system 500, fourth fuel system 600 and / or fifth fuel system 700 are substantially similar or identical, and those components having structures and / or functions substantially similar or identical to the structures and / or functions of the components of the first fuel system 200, second fuel system 400, third fuel system 500, fourth fuel system 600 and / or fifth fuel system 700. Instead, the interested reader is referred to the corresponding description above. To facilitate this processing, the same reference numerals are used for similar structures.

[0069] Figure 8 The sixth fuel system 800 does not include Figure 2 , Figure 4 , Figure 5 , Figure 6 and Figure 7A bypass valve or a throttle valve in the fuel system 200 , 400 , 500 , 600 , 700 . Figure 8 The sixth fuel system 800 includes a compensating valve 802. The compensating valve 802 is connected to Figure 5 and Figure 7 The compensating valves 502, 702 of the FMV 208 operate similarly to improve the metering accuracy of the fuel flow through the FMV 208. For example, Figure 8 As shown, the first hydraulic line 804 is fluidly coupled between the third fluid line 218 and the compensating valve 802, and the second hydraulic line 806 is coupled between the fourth fluid line 220 and the compensating valve 802. Therefore, the compensating valve 802 can sense or measure the pressure differential across the FMV 208. The third hydraulic line 808 is fluidly coupled between the compensating valve 802 and the servo valve 252 of the actuator 236. Based on the measured pressure differential, the compensating valve 802 can adjust the pressure in the third hydraulic line 808, which adjusts the force margin on the servo valve 252. Therefore, the actuator 236 can sense or measure the pressure differential across the FMV 208 and control the stroke of the variable displacement pump 206 to control the discharge flow rate and / or pressure. The compensating valve 802 improves the accuracy of the metering system by compensating for the pressure drop across the servo valve 252. In particular, the compensating valve 802 improves the variation around the nominal pressure value, so that the metered fuel output to the combustion section 118 is more accurate.

[0070] The controller 238 may operate substantially the same as disclosed in connection with the first fuel system 200 to operate the devices of the sixth fuel system 800 and control the flow rate and / or pressure of the fuel. Figure 8 , the sixth fuel system 800 does not provide power to the actuator 224 ( Figure 2 ) provides pressurized fuel. However, in other examples, the sixth fuel system 800 can provide pressurized fuel to the actuator 224, similar to Figure 2 The first fuel system 200 in.

[0071] Although Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 An example manner of implementing the controller 238 is shown in FIG. Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8One or more of the elements, processes, and / or devices shown in the example may be combined, divided, rearranged, omitted, eliminated, and / or implemented in any other manner. In addition, the example input / output module 240, the example comparator 242, the example FMV controller 244, the example pump actuator controller 246, the example bypass valve controller 248, and / or more generally, Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 The example controller 238 may be implemented by hardware alone or by hardware in combination with software and / or firmware. Thus, for example, any of the example input / output modules 240, the example comparator 242, the example FMV controller 244, the example pump actuator controller 246, the example bypass valve controller 248, and / or more generally, the example controller 238 may be implemented by programmable circuits in combination with machine-readable instructions (e.g., firmware or software), processor circuits, analog circuits, digital circuits, logic circuits, programmable processors, programmable microcontrollers, graphics processing units (GPUs), digital signal processors (DSPs), ASICs, programmable logic devices (PLDs), and / or field programmable logic devices (FPLDs) (such as FPGAs). In addition, Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 An example controller 238 may include in addition to Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 In addition to or in place of the components, processes and / or devices shown Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 One or more of the elements, processes and / or devices shown, and / or may include more than one of any or all of the elements, processes and devices shown.

[0072] Fig. 9 The flowcharts representing example machine-readable instructions and / or representing example operations are shown in Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8Controller 238, example operations may be performed by programmable circuitry to implement and / or instantiate Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 The machine-readable instructions may be provided by a programmable circuit (such as the following in combination with Fig.10 The machine-readable instructions may be one or more executable programs or portions of one or more executable programs executed by the programmable circuit 1012 shown in the example processor platform 1100 discussed above, and / or may be one or more functions or portions of functions to be performed by the example programmable circuit (e.g., FPGA). In some examples, the machine-readable instructions cause an operation, task, etc. to be performed and / or performed in an automated manner in the real world. As used herein, "automated" refers to a situation where there is no human involvement.

[0073] The program may be embodied in instructions (e.g., software and / or firmware) stored on one or more non-transitory computer-readable and / or machine-readable storage media (such as cache memory, magnetic storage devices or disks (e.g., floppy disks, hard disk drives (HDDs), etc.), optical storage devices or disks (e.g., Blu-ray discs, compact disks (CDs), digital versatile disks (DVDs), etc.), redundant arrays of independent disks (RAID), registers, ROM, solid-state drives (SSDs), SSD memory, non-volatile memory (e.g., electrically erasable programmable read-only memory (EEPROM), flash memory, etc.), volatile memory (e.g., any type of random access memory (RAM), etc.), and / or any other storage devices or storage disks).

[0074] The instructions of the non-transitory computer-readable and / or machine-readable medium may program and / or be executed by programmable circuits located in one or more hardware devices, but the entire program and / or portions thereof may alternatively be executed and / or instantiated by one or more hardware devices other than programmable circuits, and / or embodied in dedicated hardware. The machine-readable instructions may be distributed across multiple hardware devices and / or executed by two or more hardware devices (e.g., a server and a client hardware device). For example, a client hardware device may be implemented by an endpoint client hardware device (e.g., a hardware device associated with a human and / or machine user) or an intermediate client hardware device gateway (e.g., a radio access network (RAN)) that may facilitate communication between a server and an endpoint client hardware device. Similarly, a non-transitory computer-readable storage medium may include one or more media.

[0075] In addition, although the sample program is a reference Fig. 9, but many other methods of implementing the example controller 238 may be used instead. For example, the execution order of the blocks of the flowchart may be changed, and / or some of the blocks described may be changed, eliminated, or combined. Additionally or alternatively, any or all of the blocks of the flowchart may be implemented by one or more hardware circuits (e.g., processor circuits, discrete and / or integrated analog and / or digital circuits, FPGAs, ASICs, comparators, operational amplifiers (op-amps), logic circuits, etc.) that are structured to perform corresponding operations without executing software or firmware. The programmable circuits may be distributed in different network locations and / or located locally in one or more hardware devices (e.g., single-core processors (e.g., single-core CPUs), multi-core processors (e.g., multi-core CPUs, XPUs, etc.). For example, the programmable circuit may be a CPU and / or FPGA located in the same package (e.g., the same integrated circuit (IC) package or in two or more separate housings), one or more processors in a single machine, multiple processors distributed on multiple servers in a server rack, multiple processors distributed on one or more server racks, etc., and / or any combination thereof.

[0076] The machine-readable instructions described herein may be stored in one or more of a compressed format, an encrypted format, a segmented format, a compiled format, an executable format, a packaged format, etc. The machine-readable instructions as described herein may be stored as data (e.g., computer-readable data, machine-readable data, one or more bits (e.g., one or more computer-readable bits, one or more machine-readable bits, etc.), a bit stream (e.g., a computer-readable bit stream, a machine-readable bit stream, etc.), etc.) or a data structure (e.g., as part of an instruction, code, a representation of code, etc.) that can be used to create, manufacture, and / or generate machine-executable instructions. For example, the machine-readable instructions may be segmented and stored on one or more storage devices, disks, and / or computing devices (e.g., servers) located in the same or different locations (e.g., in the cloud, an edge device, etc.) of a network or a collection of networks.

[0077] The machine-readable instructions may need to be installed, modified, adapted, updated, combined, supplemented, constructed, decrypted, decompressed, unpacked, distributed, redistributed, compiled, etc., one or more so that they are directly readable, interpreted, and / or executable by a computing device and / or other machine. For example, the machine-readable instructions may be stored in multiple parts that are separately compressed, encrypted, and / or stored on separate computing devices, where the parts, when decrypted, decompressed, and / or combined, form a set of computer-executable and / or machine-executable instructions that implement one or more functions and / or operations that may together form a program such as described herein.

[0078] In another example, machine-readable instructions may be stored in a state where they can be read by programmable circuits, but require the addition of a library (e.g., a dynamic link library (DLL)), a software development kit (SDK), an application programming interface (API), etc., in order to execute the machine-readable instructions on a particular computing device or other device. In another example, it may be necessary to construct the machine-readable instructions (e.g., stored settings, data inputs, recorded network addresses, etc.) before the machine-readable instructions and / or corresponding programs can be executed in whole or in part. Therefore, as used herein, machine-readable, computer-readable and / or machine-readable media may include instructions and / or programs regardless of the specific format or state of the machine-readable instructions and / or programs.

[0079] The machine-readable instructions described herein may be represented by any past, present, or future instruction language, scripting language, programming language, etc. For example, the machine-readable instructions may be represented using any of the following languages: C, C++, Java, C#, Perl, Python, JavaScript, Hypertext Markup Language (HTML), Structured Query Language (SQL), Swift, etc.

[0080] As mentioned above, Fig. 9 The example operations of can be implemented using executable instructions (e.g., computer-readable and / or machine-readable instructions) stored on one or more non-transitory computer-readable and / or machine-readable media. As used herein, the terms non-transitory computer-readable medium, non-transitory computer-readable storage medium, non-transitory machine-readable medium, and / or non-transitory machine-readable storage medium are expressly defined to include any type of computer-readable storage device and / or storage disk, and exclude propagation signals and exclude transmission media. Examples of such non-transitory computer-readable media, non-transitory computer-readable storage media, non-transitory machine-readable media, and / or non-transitory machine-readable storage media include optical storage devices, magnetic storage devices, HDDs, flash memory, read-only memory (ROM), CDs, DVDs, caches, any type of RAM, registers, and / or any other storage device or storage disk that stores information for any duration (e.g., an extended period of time, permanent, transient instances, temporary buffering, and / or cached information).

[0081] As used herein, the terms "non-transitory computer-readable storage device" and "non-transitory machine-readable storage device" are defined to include any physical (mechanical, magnetic and / or electrical) hardware that retains information over a period of time, but excludes propagating signals and excludes transmission media. Examples of non-transitory computer-readable storage devices and / or non-transitory machine-readable storage devices include any type of random access memory, any type of read-only memory, solid-state memory, flash memory, optical disks, magnetic disks, disk drives, and / or redundant array of independent disks (RAID) systems. As used herein, the term "device" refers to a physical structure (such as a mechanical and / or electrical device, hardware, and / or circuit) that may or may not be constructed from computer-readable instructions, machine-readable instructions, etc., and / or manufactured to perform computer-readable instructions, machine-readable instructions, etc.

[0082] Fig. 9 is a flow diagram representing example machine readable instructions and / or example operations 900 that may be executed and / or instantiated by programmable circuitry to operate a fuel system. The example machine readable instructions and / or example operations 900 may be implemented in conjunction with any of the fuel systems 200, 400, 500, 600, 700, 800 disclosed herein.

[0083] At block 902, controller 238 measures one or more parameters, such as temperature, pressure, speed, etc. For example, input / output module 240 may receive signals from one or more sensors, such as sensors 254, 256, 258. In some examples, comparator 242 compares the measured parameters to one or more threshold values.

[0084] At block 904, the FMV controller 244 controls the FMV 208 based on the measured parameters. Additionally or alternatively, the input / output module 240 may receive input signals (e.g., commands) from one or more other devices, such as pilot controls (e.g., thrust levers), and the FMV controller 244 may control the FMV 208 based on the input signals.

[0085] At box 906, the pump actuator controller 246 controls the variable displacement pump 206 based on the measured parameters. For example, the pump actuator controller 246 can control the actuator 236 to adjust the stroke length of the variable displacement pump 206, which affects the discharge flow rate and / or pressure of the variable displacement pump 206. In some examples, the pump actuator controller 246 controls the actuator 236 based on the outlet pressure of the FMV 208 or the pressure differential across the FMV 208. Additionally or alternatively, the pump actuator controller 246 can control the actuator 236 to achieve a target pump discharge flow rate set by a full authority digital engine control (FADEC) (e.g., operate at or near the target pump discharge flow rate).

[0086] At block 908 , the bypass valve controller 248 controls the bypass valve 228 or the throttle valve 602 based on the measured parameter. For example, the bypass valve controller 248 may control the bypass valve 228 or the throttle valve 602 based on the outlet pressure of the FMV 208 or the pressure differential across the FMV 208 .

[0087] At block 910, controller 238 determines whether turbine engine 100 is still running. If turbine engine 100 is not running (eg, turbine engine 100 has been shut down), then Fig. 9 The example process ends. However, if the turbine engine 100 is still running, control returns to box 902 and repeats the example process. The process can be repeated at a relatively high frequency. In particular, the controller 238 can continuously monitor the sensed parameters and adjust various devices of the fuel system.

[0088] Fig.10 is structured to execute and / or instantiate Fig. 9 Example machine readable instructions and / or example operations to implement Figure 2 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 238 of the controller 238. The programmable circuit platform 1000 can be, for example, an electronic engine controller (EEC), a full authority digital engine control (FADEC), a server, a personal computer, a workstation, a self-learning machine (e.g., a neural network), a mobile device (e.g., a cell phone, a smart phone, a tablet computer such as an iPad), or a computer. TM ), a personal digital assistant (PDA), an Internet appliance, a DVD player, a CD player, a digital video recorder, or any other type of computing and / or electronic device.

[0089] The programmable circuit platform 1000 of the illustrated example includes a programmable circuit 1012. The programmable circuit 1012 of the illustrated example is hardware. For example, the programmable circuit 1012 can be implemented by one or more integrated circuits, logic circuits, FPGAs, microprocessors, CPUs, GPUs, DSPs, and / or microcontrollers from any desired series or manufacturer. The programmable circuit 1012 can be implemented by one or more semiconductor-based (e.g., silicon-based) devices. In this example, the programmable circuit 1012 implements the input / output module 240, the comparator 242, the FMV controller 244, the pump actuator controller 246, and the bypass valve controller 248 of the example controller 238.

[0090] The programmable circuit 1012 of the illustrated example includes a local memory 1013 (e.g., cache, registers, etc.). The programmable circuit 1012 of the illustrated example communicates with a main memory 1014, 1016 including a volatile memory 1014 and a non-volatile memory 1016 via a bus 1018. The volatile memory 1014 may be composed of a synchronous dynamic random access memory (SDRAM), a dynamic random access memory (DRAM), Dynamic Random Access Memory The non-volatile memory 1016 may be implemented by flash memory and / or any other desired type of memory device. Access to the main memories 1014, 1016 of the illustrated example is controlled by a memory controller 1017. In some examples, the memory controller 1017 may be implemented by one or more integrated circuits, logic circuits, microcontrollers, or any other type of circuitry from any desired family or manufacturer to manage the flow of data to and from the main memories 1014, 1016.

[0091] The programmable circuit platform 1000 of the illustrated example also includes an interface circuit 1020. The interface circuit 1020 may be configured according to any type of interface standard (such as an Ethernet interface, a universal serial bus (USB) interface, interface, a near field communication (NFC) interface, a peripheral component interconnect (PCI) interface, and / or a peripheral component interconnect express (PCIe) interface) are implemented by hardware.

[0092] In the example shown, one or more input devices 1022 are connected to the interface circuit 1020. The input devices 1022 allow a user (e.g., a human user, a machine user, etc.) to input data and / or commands into the programmable circuit 1012. The input devices 1022 may be implemented by sensors 254, 256, 258. Additionally or alternatively, the input devices 1022 may be implemented by, for example, pilot controls, audio sensors, microphones, cameras (still or video), keyboards, buttons, mice, touch screens, track pads, track balls, isopoint devices, and / or voice recognition systems.

[0093] One or more output devices 1024 are also connected to the interface circuit 1020 of the illustrated example. The output device 1024 may include the servo valve 212, the bypass valve 228, the actuator 236, the servo valve 252, the compensation valve 502, the throttle valve 602, the compensation valve 702, and / or the compensation valve 802 of the FMV 208. Additionally or alternatively, the output device 1024 may be implemented by, for example, a display device (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), a cathode ray tube (CRT) display, an in-place switching (IPS) display, a touch screen, etc.), a tactile output device, a printer, and / or a speaker. Therefore, the interface circuit 1020 of the illustrated example typically includes a graphics driver card, a graphics driver chip, and / or a graphics processor circuit, such as a GPU.

[0094] The interface circuitry 1020 of the illustrated example also includes a communication device (such as a transmitter, receiver, transceiver, modem, residential gateway, wireless access point, and / or network interface) to facilitate data exchange with an external machine (e.g., any kind of computing device) via the network 1026. Communication may be through, for example, an Ethernet connection, a digital subscriber line (DSL) connection, a telephone line connection, a coaxial cable system, a satellite system, an off-site wireless system, an on-site wireless system, a cellular telephone system, an optical connection, etc.

[0095] The programmable circuit platform 1000 of the illustrated example also includes one or more mass storage disks or devices 1028 for storing firmware, software, and / or data. Examples of such mass storage disks or devices 1028 include magnetic storage devices (e.g., floppy disks, drives, HDDs, etc.), optical storage devices (e.g., Blu-ray disks, CDs, DVDs, etc.), RAID systems, and / or solid-state storage disks or devices, such as flash memory devices and / or SSDs.

[0096] can be Fig. 9 The machine-readable instructions 1032 implemented by the machine-readable instructions may be stored in the mass storage device 1028, the volatile memory 1014, the non-volatile memory 1016, and / or on at least one removable non-transitory computer-readable storage medium (such as a CD or DVD).

[0097] As used herein, the phrase "communication," including variations thereof, encompasses direct communication and / or indirect communication through one or more intermediate components, and does not require direct physical (e.g., wired) communication and / or continuous communication, but additionally includes selective communication at periodic intervals, predetermined intervals, non-periodic intervals, and / or one-time events.

[0098] As used herein, "programmable circuit" is defined to include (i) one or more special purpose circuits (e.g., application specific circuits (ASICs)) structured to perform specific operations and including one or more semiconductor-based logic devices (e.g., electrical hardware implemented by one or more transistors), and / or (ii) one or more general-purpose semiconductor-based circuits that can be programmed with instructions to perform specific functions and / or operations and include one or more semiconductor-based logic devices (e.g., electrical hardware implemented by one or more transistors). Examples of programmable circuits include a programmable microprocessor (such as a central processing unit (CPU)) that can execute a first instruction to perform one or more operations and / or functions, a field programmable gate array (FPGA) that can be programmed with a second instruction so that the configuration and / or structure of the FPGA instantiates one or more operations and / or functions corresponding to the first instruction, a graphics processor unit (GPU) that can execute a first instruction to perform one or more operations and / or functions, a digital signal processor (DSP) that can execute a first instruction to perform one or more operations and / or functions, an XPU, a network processing unit (NPU), one or more microcontrollers that can execute a first instruction to perform one or more operations and / or functions, and / or an integrated circuit (such as an application specific integrated circuit (ASIC)). For example, the XPU may be implemented by a heterogeneous computing system including multiple types of programmable circuits (e.g., one or more FPGAs, one or more CPUs, one or more GPUs, one or more NPUs, one or more DSPs, etc., and / or any combination thereof) and orchestration technology (e.g., an application programming interface (API)) that may assign computing tasks to any of the multiple types of programmable circuits that are suitable and available to perform the computing tasks.

[0099] It will be appreciated that an example fuel system is disclosed herein that utilizes a variable displacement pump to achieve adjustability of the discharge flow rate and / or pressure of the pump independently of the turbine engine speed. This enables the pump to operate at a lower level to reduce (e.g., minimize) excess fuel flow. This also reduces or limits waste heat that would otherwise be added to the fuel by a fixed displacement pump that overproduces pressurized fuel. Reducing or limiting the amount of added heat can reduce or eliminate the disadvantages of adding heat described herein, such as fuel varnishing or coke formation.

[0100] Further examples and example combinations thereof are provided by the subject matter of the following clauses:

[0101] A turbine engine for an aircraft, the turbine engine comprising: a gas turbine engine having a combustion section; and a fuel system, the fuel system providing fuel to the combustion section. The fuel system comprises a variable displacement pump, the variable displacement pump being driven by an accessory gearbox powered by a shaft of the gas turbine engine. The variable displacement pump has an inlet side and an outlet side. The variable displacement pump comprises an actuator, the actuator being configured to adjust the discharge flow rate of the variable displacement pump. The fuel system further comprises: a fuel metering valve, the fuel metering valve being configured to receive pressurized fuel from the variable displacement pump and control the flow rate of the pressurized fuel to the combustion section; and a bypass valve, the bypass valve fluidly coupling the outlet side and the inlet side of the variable displacement pump to direct an excess portion of the pressurized fuel at the outlet side back to the inlet side.

[0102] A turbine engine according to any preceding clause, wherein the variable displacement pump is a variable displacement vane pump or a variable displacement piston pump.

[0103] A turbine engine as described in any preceding clause, wherein the actuator is configured to adjust the discharge flow rate of the variable displacement pump based on an outlet pressure of the fuel metering valve.

[0104] A turbine engine as recited in any preceding clause, wherein the fuel system further comprises a controller that operates the actuator to achieve a target pump discharge flow rate.

[0105] A turbine engine as claimed in any preceding clause, wherein the target pump discharge flow rate is set by a full authority digital engine control (FADEC).

[0106] A turbine engine as in any preceding clause, wherein the actuator comprises a servo valve, and wherein the servo valve is fluidly coupled to the inlet side and the outlet side of the variable displacement pump.

[0107] A turbine engine as recited in any preceding clause, wherein the bypass valve is configured to control an amount of the pressurized fuel directed from the outlet side to the inlet side based on a pressure differential across the fuel metering valve.

[0108] A turbine engine as claimed in any preceding clause, wherein the fuel system comprises a hydraulic line fluidly coupling the bypass valve and an outlet side of the fuel metering valve.

[0109] A turbine engine as claimed in any preceding clause, wherein the fuel system comprises a compensator valve configured to adjust a force margin on the bypass valve based on the pressure differential across the fuel metering valve.

[0110] A turbine engine as recited in any preceding clause, wherein the fuel system includes a controller configured to operate the bypass valve based on a pressure differential across the fuel metering valve.

[0111] A turbine engine as claimed in any preceding clause, wherein the fuel system comprises a boost pump upstream of the variable displacement pump.

[0112] A turbine engine as claimed in any preceding clause, wherein the boost pump is configured to be driven by the accessory gearbox.

[0113] A turbine engine for an aircraft, the turbine engine comprising: a gas turbine engine having a combustion section; and a fuel system, the fuel system providing fuel to the combustion section. The fuel system comprises a variable displacement pump, the variable displacement pump being driven by an accessory gearbox powered by a shaft of the turbine engine. The variable displacement pump comprises an actuator, the actuator being configured to adjust a discharge flow rate of the variable displacement pump. The fuel system further comprises: a fuel metering valve, the fuel metering valve being configured to receive pressurized fuel from the variable displacement pump; and a throttle valve, the throttle valve being positioned between the fuel metering valve and the combustion section of the gas turbine engine. The throttle valve is configured to reduce the pressure of the pressurized fuel to the combustion section.

[0114] A turbine engine as described in any preceding clause, wherein the throttle valve is configured to control an amount of the pressurized fuel directed from the outlet side to the inlet side based on a pressure differential across the fuel metering valve.

[0115] A turbine engine as claimed in any preceding clause, wherein the fuel system comprises a hydraulic line fluidly coupling the throttle valve and an inlet side of the fuel metering valve.

[0116] A turbine engine as claimed in any preceding clause, wherein the fuel system comprises a compensator valve configured to adjust a force margin on the throttle valve based on the pressure differential across the fuel metering valve.

[0117] A turbine engine according to any preceding clause, wherein the variable displacement pump is a variable displacement vane pump or a variable displacement piston pump.

[0118] A non-transitory machine-readable storage medium comprising instructions that, when executed, cause a programmable circuit to measure a parameter of a fuel system of a gas turbine engine. The fuel system comprises: a variable displacement pump driven by an accessory gearbox powered by a shaft of the gas turbine engine, the variable displacement pump comprising an actuator configured to adjust a discharge flow rate of the variable displacement pump; a fuel metering valve configured to receive pressurized fuel from the variable displacement pump, the fuel metering valve controlling a flow rate of the pressurized fuel to a combustion section of the gas turbine engine; and a bypass valve fluidly coupling an outlet side of the variable displacement pump and an inlet side of the variable displacement pump to direct an excess portion of the pressurized fuel at the outlet side back to the inlet side. The instructions further cause the programmable circuit to control the variable displacement pump based on the measured parameter.

[0119] The non-transitory machine-readable storage medium of any preceding clause, wherein the measured parameter is an outlet pressure of the fuel metering valve.

[0120] The non-transitory machine-readable storage medium of any preceding clause, wherein the instructions, when executed, cause the programmable circuit to control the bypass valve based on a pressure differential across the fuel metering valve.

[0121] A turbine engine for an aircraft, the turbine engine comprising: a gas turbine engine having a combustion section; and a fuel system that provides fuel to the combustion section. The fuel system comprises a variable displacement pump driven by an accessory gearbox powered by a shaft of the turbine engine. The variable displacement pump comprises an actuator that adjusts the discharge flow rate of the variable displacement pump. The actuator comprises a servo valve. The fuel system also comprises a fuel metering valve that receives pressurized fuel from the variable displacement pump. The fuel system comprises a compensating valve that adjusts the force margin on the servo valve based on the pressure differential across the fuel metering valve.

[0122] A method includes measuring a parameter of a fuel system of a gas turbine engine. The fuel system includes a variable displacement pump driven by an accessory gearbox powered by a shaft of the gas turbine engine, the variable displacement pump including an actuator to adjust a discharge flow rate of the variable displacement pump, and a fuel metering valve receiving pressurized fuel from the variable displacement pump, the fuel metering valve controlling a flow rate of the pressurized fuel to a combustion section of the gas turbine engine. The method further includes controlling the fuel metering valve based on the measured parameter, controlling the variable displacement pump based on the measured parameter, and controlling a bypass valve or a throttle valve based on the measured parameter.

[0123] A method as in any preceding clause, further comprising determining whether the gas turbine engine is still running.

[0124] The method according to any preceding clause, wherein the measured parameter is the outlet pressure of the fuel metering valve. Although certain example methods, apparatus, and articles are disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles that fully fall within the scope of the claims of this patent.

Claims

1. A turbine engine for an aircraft, characterized in that: The turbine engine comprises: a gas turbine engine having a combustion section; and A fuel system, the fuel system providing fuel to the combustion section, the fuel system comprising: a variable displacement pump driven by an accessory gearbox powered by a shaft of the gas turbine engine, the variable displacement pump having an inlet side and an outlet side, the variable displacement pump including an actuator configured to adjust a discharge flow rate of the variable displacement pump; a fuel metering valve configured to receive pressurized fuel from the variable displacement pump and control a flow rate of the pressurized fuel to the combustion section; and A bypass valve fluidly couples the outlet side and the inlet side of the variable displacement pump to direct an excess portion of the pressurized fuel at the outlet side back to the inlet side.

2. The turbine engine according to claim 1, characterized in that in, The variable displacement pump is a variable displacement vane pump or a variable displacement piston pump.

3. The turbine engine according to claim 1, characterized in that: in, The actuator is configured to adjust the discharge flow rate of the variable displacement pump based on an outlet pressure of the fuel metering valve.

4. The turbine engine according to claim 1, characterized in that: in, The fuel system further includes a controller that operates the actuator to achieve a target pump discharge flow rate.

5. The turbine engine according to claim 4, characterized in that in, The target pump discharge flow rate is set by a full authority digital engine control (FADEC).

6. The turbine engine according to claim 1, characterized in that in, The actuator includes a servo valve, and wherein the servo valve is fluidly coupled to the inlet side and the outlet side of the variable displacement pump.

7. The turbine engine according to claim 1, characterized in that in, The bypass valve is configured to control an amount of the pressurized fuel directed from the outlet side to the inlet side based on a pressure differential across the fuel metering valve.

8. The turbine engine according to claim 7, characterized in that in, The fuel system includes a hydraulic line fluidly coupling the bypass valve and an outlet side of the fuel metering valve.

9. The turbine engine according to claim 8, characterized in that in, The fuel system includes a compensator valve configured to adjust a force margin on the bypass valve based on the pressure differential across the fuel metering valve.

10. The turbine engine according to claim 1, characterized in that in, The fuel system includes a controller configured to operate the bypass valve based on a pressure differential across the fuel metering valve.

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