Aircraft propulsion system having turbine engine coupled to generator whose power is limited as function of engine speed

Abstract

An aircraft propulsion system (12) includes a turbine engine (20), a control system (24), a member (72) for determining a current engine speed (Rc) of a body of the turbine engine (20), and a rotary machine (22) coupled to a driveshaft of the turbine engine (20) to generate electrical power by withdrawing mechanical power from the driveshaft. The control system (24) is configured to limit a current electric power (Pc) generated by the rotating machine (22) to a maximum allowable electric power (Pmax) as a function of a current engine speed (Rc) prior to acceleration at least when the engine body is in an acceleration phase. The propulsion system further comprises means (74) for determining a current electric power (Pc) generated by the rotating machine (22), the control system (24) being configured to establish the engine speed above an idle speed (Rr), which is a function of the current electric power.

Description

Technical Field

[0001] The present invention relates to an aircraft propulsion system, an aircraft propulsion system of this type comprising a gas turbine engine having a combustion chamber and an engine body, the engine body comprising a turbine located downstream of the combustion chamber, a compressor located upstream of the combustion chamber, and a transmission shaft for driving the compressor via the turbine, the propulsion system also comprising a control system, a component for determining a current engine speed of the engine body, and a rotating machine connected to the transmission shaft for generating electricity by obtaining mechanical power from the transmission shaft.

[0002] The invention also relates to a method for controlling an aircraft propulsion system of the type described above. Background Art

[0003] Propulsion systems of the aforementioned type are known, for example, from EP 3 845 750 A1 and US Pat. No. 7,514,810 B2.

[0004] On these known systems, the engine idle speed (i.e., the rotational speed of the engine body when the aircraft does not need propulsion) is generally a single value and does not depend on the power generated by the rotating machine. Therefore, no matter how much power the rotating machine generates, the engine idle speed is the same.

[0005] It is also known that, for safety reasons, the propulsion system with which an aircraft is equipped must in any case be able to reestablish a large portion of the full throttle power of the propulsion system (generally more than 90% of the full throttle power) within a very short critical time (generally equal to 8 seconds). In particular, this requires that the engine body of the idling gas turbine engine must be able to reach a large percentage of the full throttle engine speed of the engine body (i.e. the engine speed when the gas turbine engine produces the full throttle thrust of the gas turbine engine) within said critical time. It is therefore advisable to dimension the engine idle speed so as to be able to meet this objective when the engine body is accelerated to the maximum capabilities of the engine body.

[0006] It is also known that the maximum acceleration rate that the engine body of a gas turbine engine can tolerate depends on the drag torque applied to the engine body. Specifically, the acceleration rate of the engine body of a gas turbine engine is a function of the difference between the temperature at the outlet of the combustion chamber during the acceleration phase and the temperature at the outlet of the combustion chamber when the gas turbine engine is at a stable speed: the greater the temperature difference, the greater the acceleration rate. However, this difference cannot be increased arbitrarily, because for a given engine speed, the temperature at the outlet of the combustion chamber has an upper limit: the higher the temperature at the outlet of the combustion chamber, the lower the flow rate at the outlet of the compressor, so that above the threshold temperature, the outlet flow rate is insufficient and the compressor stalls. Therefore, the maximum acceleration rate is a function of the difference between the threshold temperature and the temperature at a stable speed. However, for a given engine speed, the greater the drag torque applied, the higher the temperature at a stable speed, and therefore the smaller the difference between the threshold temperature and the temperature at a stable speed, and therefore the smaller the maximum acceleration rate.

[0007] It will therefore be readily appreciated that, in a propulsion system of the type described above, the maximum rate of acceleration that can be tolerated by the engine body decreases as the electrical power produced by the rotating machine increases.

[0008] Therefore, in known propulsion systems, the maximum acceleration rate allowed at engine idle is at most equal to the maximum acceleration rate that the engine body can tolerate when the power generated by the rotary machine is at a maximum value. In particular, the engine idle speed is the same regardless of the power generated by the rotary machine, and any other value of the maximum allowed acceleration rate will cause the compressor to stall when the power generated by the rotary machine is close to the maximum value of this power.

[0009] Therefore, in known propulsion systems, the engine idle speed is set to a value such that when the electric power generated by the rotating machine is at a maximum, the propulsion system manages to reestablish most of the maximum thrust of the propulsion system within a critical time by applying the maximum acceleration rate that the engine body can tolerate.

[0010] However, these known systems do not provide complete satisfaction. Specifically, as the thrust generated by the aircraft propulsion system increases and the drag of the aircraft propulsion system decreases, the ratio of drag to thrust at engine idle speed tends to decrease. However, this ratio must be kept high enough so that the descent gradient at flight idle speed is sufficiently steep. If this cannot be done, devices for reducing aircraft lift or increasing aircraft drag must be used, which consumes fuel. Likewise, at ground idle speed, too high an idle thrust will cause the brakes to wear more quickly. Summary of the invention

[0011] One subject of the present invention is to reduce the idle thrust of an aircraft propulsion system.

[0012] To this end, according to a first aspect, the subject of the invention is a propulsion system of the aforementioned type, wherein the control system is configured to limit the current electric power generated by the rotary machine to a maximum permissible electric power, at least when the engine body is in an acceleration phase, the maximum permissible electric power being a function of the current engine speed before acceleration, and wherein the propulsion system comprises means for determining the current electric power generated by the rotary machine, the control system being configured to establish the engine speed above the idle speed, the idle speed being a function of the current electric power.

[0013] According to a particular embodiment of the invention, the propulsion system also has one or more of the following features, taken alone or in any possible technical combination:

[0014] - the propulsion system comprises a system for deriving a future demand of the aircraft for electric power generated by the rotary machine, the control system being configured to accelerate the engine body when said future demand is greater than the maximum allowed electric power;

[0015] - when the engine speed is established at idle speed, the current power constitutes the maximum permissible power;

[0016] - the idle speed is greater than or equal to the acceleration limit speed, for which the engine body is accelerated from said acceleration limit speed to the stall limit while the rotary machine is generating current power, so that the engine body reaches the target speed at which the gas turbine engine generates a large percentage of full throttle thrust within a specified time of less than or equal to 10 seconds without stalling;

[0017] - the idle speed is greater than or equal to the overheat limit speed, for which the temperature of the gas at the outlet of the gas turbine engine is equal to a predetermined maximum temperature when the engine body rotates at said overheat limit speed while the rotating machine generates current electricity;

[0018] - Idle speed is equal to the maximum value of acceleration limit speed and overheat limit speed;

[0019] - the maximum permissible power is less than or equal to the acceleration limit power for which the engine body is accelerated from the current engine speed to the stall limit when the rotary machine generates said acceleration limit power, so that the engine body reaches the target speed at which the gas turbine engine generates a large percentage of full throttle thrust within a prescribed time of less than or equal to 10 seconds without stalling;

[0020] - the maximum permissible power is less than or equal to the overheat limit power for which the temperature of the gas at the outlet of the gas turbine engine is equal to a predetermined maximum temperature when the engine body rotates at the current rotation speed and the rotary machine generates said overheat limit power;

[0021] - The maximum allowable power is equal to the minimum value of the acceleration limit power and the overheat limit power;

[0022] - the control system is configured to limit the electric power generated by the rotary machine when the engine body is not in an acceleration phase;

[0023] - the propulsion system comprises an electric motor coupled to a drive shaft; and

[0024] - Gas turbine engines are turbojet engines.

[0025] According to a second aspect, another subject of the invention is a method for controlling an aircraft propulsion system, the propulsion system comprising a gas turbine engine having a combustion chamber and an engine body, the engine body comprising a turbine located downstream of the combustion chamber, a compressor located upstream of the combustion chamber, and a transmission shaft for driving the compressor via the turbine, the propulsion system also comprising a rotary machine coupled to the transmission shaft for generating electrical power by extracting mechanical power from the transmission shaft, the control method comprising the following successive steps:

[0026] - determine the current power produced by the rotating machinery,

[0027] - defining the idle speed as a function of the current power, and establishing an engine speed above the idle speed,

[0028] - determine the current engine speed of the engine body,

[0029] - defining the maximum permissible power as a function of the current engine speed, and

[0030] - Accelerating the engine body, limiting the current power generated by the rotating machine to the maximum permissible power.

[0031] According to a particular embodiment of the invention, the control method also has one or more of the following features, taken alone or in any possible technical combination:

[0032] - The control method further comprises the following steps:

[0033] ○ Derive future demand for electrical power generated by rotating machines for aircraft,

[0034] ○ modifying the idle speed so that the idle speed meets the future demand,

[0035] ○ Compare the new idle speed to the current engine speed, and

[0036] ○ If the new idle speed is greater than the current engine speed, the engine body is accelerated;

[0037] - during the step of establishing the engine speed, the engine speed is established at idle speed, the current power then constituting the maximum permissible power;

[0038] - the control method further comprises the steps of: accelerating the engine body from said idle speed when the rotary machine generates current power, so that the engine body reaches a target speed without stalling within a prescribed time of less than or equal to 10 seconds, at which target speed the gas turbine engine generates a large percentage of full throttle thrust;

[0039] -Limiting idle speed includes the following sub-steps:

[0040] o calculating an acceleration limit speed from which the engine body is accelerated to a stall limit while the rotating machine is generating current electrical power so that the engine body reaches a target speed at which the gas turbine engine generates a large percentage of full throttle thrust within a specified time of less than or equal to 10 seconds without stalling; and

[0041] ○ Assign a value greater than or equal to the acceleration limit speed to the idle speed;

[0042] -Limiting idle speed includes the following sub-steps:

[0043] o calculating a superheat limit speed for which the temperature of the gas at the outlet of the gas turbine engine is equal to a predetermined maximum temperature when the engine body rotates at said superheat limit speed while the rotating machine generates current power, and

[0044] ○ Assign a value greater than or equal to the overheat limit speed to the idle speed;

[0045] - limiting the idle speed comprises: assigning a value equal to the maximum value of the acceleration limit speed and the overheat limit speed to the idle speed;

[0046] - The control method further comprises the steps of: accelerating the engine body from a current engine speed when the rotary machine is producing a maximum allowable electric power so that the engine body reaches a target speed at which the gas turbine engine produces a large percentage of full throttle thrust within a prescribed time of less than or equal to 10 seconds without stalling;

[0047] - Defining the maximum allowed power includes the following sub-steps:

[0048] o calculating an acceleration limit power for which the engine body is accelerated from a current engine speed to a stall limit when the rotary machine generates the acceleration limit power so that the engine body reaches a target speed at which the gas turbine engine generates a maximum percentage of full throttle thrust within a prescribed time of less than or equal to 10 seconds without stalling, and

[0049] ○ Allocate a value less than or equal to the acceleration limit power to the maximum power;

[0050] - Defining the maximum allowed power includes the following sub-steps:

[0051] o calculating an overheat limit power for which the temperature of gas at the outlet of the gas turbine engine is equal to a predetermined maximum temperature when the engine body rotates at a current rotation speed and the rotary machine generates the overheat limit power, and

[0052] ○ Allocate a value less than or equal to the overheat limit power to the maximum power;

[0053] - defining the maximum allowable electric power includes: assigning a value equal to a minimum value of the acceleration limit electric power and the overheat limit electric power to the maximum electric power;

[0054] - before the step of accelerating the engine body, the method further comprises: a step of limiting the electric power generated by the rotary machine when the engine body rotates at the current engine speed; and

[0055] The acceleration step comprises injecting mechanical power into the transmission shaft via an electric motor coupled to the transmission shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Other features and advantages of the invention will become apparent on reading the following description given by way of example only and with reference to the accompanying drawings, in which:

[0057] - Figure 1 is a top view of an aircraft including two propulsion systems according to an exemplary embodiment of the present invention,

[0058] - Figure 2 yes Figure 1 A block diagram of one of the propulsion systems of an aircraft,

[0059] - Figure 3 yes Figure 2 A simplified longitudinal section of a gas turbine engine of a propulsion system,

[0060] - Figure 4 It is shown by Figure 2 A diagram of a method implemented in a control system of a propulsion system,

[0061] - Figure 5 is given Figure 2 A graph showing the relationship between the current power of the propulsion system and the engine idle speed,

[0062] - Figure 6 It is shown in different situations Figure 3 A first graph of a characteristic curve of a compressor of a gas turbine engine,

[0063] - Figure 7 is given in different situations Figure 3A first graph of the engine speed of a gas turbine engine versus time,

[0064] - Figure 8 is given in different situations Figure 3 a first graph showing the relationship between the temperature at the outlet of a gas turbine engine and the engine speed,

[0065] - Fig. 9 is given Figure 2 A graph showing the relationship between the maximum permissible power of the propulsion system and the current engine speed,

[0066] - Fig.10 is given in different situations Figure 3 A second graph of the engine speed of the gas turbine engine varying with time,

[0067] - Fig.11 It is shown in different situations Figure 3 a second graph of a characteristic curve of a compressor of a gas turbine engine, and

[0068] - Fig.12 is given in different situations Figure 3 A second graph showing the relationship between the temperature at the outlet of the gas turbine engine and the engine speed. DETAILED DESCRIPTION

[0069] Figure 1 The illustrated aircraft 10 includes a propulsion system 12 for propelling the aircraft.

[0070] In the example shown, the aircraft 10 is an airplane. The aircraft generally comprises a fuselage 14, an empennage 16 and two wings 18. Here, the number of propulsion systems 12 is two, and each propulsion system is housed under a respective wing 18. In a variant (not shown), the propulsion systems 12 are arranged along the fuselage 14, for example, near the empennage 16. In another variant (also not shown), the aircraft 10 comprises a single propulsion system 12 or at least three propulsion systems 12.

[0071] Aircraft 10 also includes an electrical power system (not shown).

[0072] Figure 2 One of the propulsion systems 12 is shown.

[0073] The propulsion system 12 includes a gas turbine engine 20, a rotating machine 22 for generating electrical power, and a control system 24. In the example shown, the propulsion system 12 also includes at least one auxiliary power source 26 (eg, a battery or fuel cell) and an electric motor 28.

[0074] The propulsion system 12 also comprises transmission means 29 to transmit the electrical power generated by the rotary machine 22 or provided by the or each auxiliary electrical power source 26 to the electrical system of the aircraft 10 .

[0075] Reference Figure 3 The gas turbine engine 20 generally includes an engine casing 30 , an internal air path 32 for communicating air flow through the engine casing 30 , a combustion chamber 34 housed in the air path 32 , an engine block 36 , and an exhaust nozzle 38 .

[0076] In the remainder of this document, the terms “upstream” and “downstream” will be understood with reference to the flow direction of the air flow through the air path 32 .

[0077] The engine body 36 includes a compressor 40, a turbine 42, and a transmission shaft 44 that couples the turbine 42 to the compressor 40 to drive the compressor 40 via the turbine 42. The compressor 40 is arranged upstream of the combustion chamber 34 and supplies compressed air to the combustion chamber 34. The turbine 42 is arranged downstream of the combustion chamber 34 and receives exhaust gas leaving the combustion chamber 34.

[0078] The transmission shaft 44 has as a rotation axis a longitudinal axis X. The longitudinal axis X is generally an axis of angular symmetry of the gas turbine engine 20, ie there is at least one angle about the longitudinal axis X about which the gas turbine engine 20 is rotationally invariant.

[0079] The transmission shaft 44 is rotationally guided relative to the engine housing 30 by means of bearings (not shown).

[0080] The engine body 36 is rotatable about the axis X at a rotational speed known as the engine speed. This engine speed is in particular a function of the temperature of the gases at the outlet of the combustion chamber 34 .

[0081] In the example shown, the gas turbine engine 20 is a multi-body gas turbine engine, in particular a twin-body gas turbine engine, which includes a low-pressure body 50 in addition to the engine body 36. The engine body 36 then constitutes a high-pressure body, the compressor 40 is a high-pressure compressor, the turbine 42 is a high-pressure turbine, and the transmission shaft 44 is a high-pressure shaft.

[0082] The low-pressure body 50 includes a low-pressure compressor 52 , a low-pressure turbine 54 , and a low-pressure shaft 56 that couples the low-pressure turbine 54 to the low-pressure compressor 52 to drive the low-pressure compressor 52 via the low-pressure turbine 54 .

[0083] The low-pressure compressor 52 is arranged upstream of the high-pressure compressor 40 and supplies compressed air to the high-pressure compressor 40. The low-pressure turbine 54 is arranged downstream of the high-pressure turbine 42 and receives exhaust gas leaving the high-pressure turbine 42.

[0084] The low-pressure shaft 56 is rotationally guided relative to the engine housing 30 by means of bearings (not shown).

[0085] The low-pressure shaft 56 is coaxial with the high-pressure shaft 44 . Therefore, the low-pressure shaft 56 also has a longitudinal axis X as a rotation axis. In particular, the low-pressure shaft 56 extends inside the high-pressure shaft 44 .

[0086] In the example shown, the gas turbine engine 20 is also a bypass gas turbine engine that includes a fan 60 to drive air flow into an outer air flow path 62 around the engine casing 30. Thus, a primary air flow A (hot) composed of a portion of the air flow driven in the inner air flow path 32 and a secondary air flow B (cold) composed of a portion of the air flow driven in the outer air flow path 62 can be distinguished.

[0087] Advantageously, the gas turbine engine 20 is a gas turbine engine with a high bypass ratio, the bypass ratio being defined as the ratio of the flow rate of the secondary flow B (cold) to the flow rate of the primary flow A (hot).

[0088] The fan 60 includes a fan disk 64 that is equipped with fan blades 66 at the outer periphery of the fan disk that drive an air flow through the outer air flow path 62 when set into rotation.

[0089] Here, the fan 60 is arranged upstream of the inner air flow path 32 and also drives the air flow through the inner air flow path 32 .

[0090] Here, an outer air flow path 62 is defined between the engine case 30 and a fan case 67 surrounding the fan 60 .

[0091] The fan 60 is rotationally driven by the low-pressure turbine 54 via the low-pressure shaft 56. In the example shown, the drive is indirect so that the fan 60 can rotate at a speed lower than the speed of the low-pressure turbine 54. To this end, the gas turbine engine 20 here includes a fan shaft 68, on which the fan disk 64 is fixedly mounted, and a reducer 70, which couples the fan shaft 68 to the low-pressure shaft 56. Therefore, the fan 60 is rotationally driven by the low-pressure shaft 56 via the reducer 70 and the fan shaft 68.

[0092] The fan shaft 68 is rotationally guided relative to the engine housing 30 by means of bearings (not shown).

[0093] The gas turbine engine 20 is typically a turbojet engine.

[0094] like Figure 3As shown, the rotary machine 22 is coupled to the high voltage shaft 44 to be rotationally driven by the high voltage shaft 44. The rotary machine 22 is adapted to generate electricity by extracting mechanical power from the high voltage shaft 44.

[0095] Advantageously, the rotating machine 22 is adapted to be separated from the high-pressure shaft 44 .

[0096] Still refer to Figure 3 The electric motor 28 is coupled to the high-voltage shaft 44 to drive said high-voltage shaft 44 in rotation about the axis X. The motor 28 is suitable for converting electricity into mechanical power and injecting the mechanical power into the high-voltage shaft 44 .

[0097] Advantageously, the electric motor 28 is adapted to be separate from the high-pressure shaft 44 .

[0098] Return to Figure 2 The control system 24 includes an engine control module 72 and a module 74 for commanding power. The control system 24 also includes a system 76 for regulating the power output device and a system 78 for managing the engine idle speed.

[0099] The engine control module 72 is configured to control the engine speed of the engine body 36. To this end, the engine control module 72 is configured to determine the current speed R of the engine body 36. c , and transmits at least one command parameter P1 , P2 to the gas turbine engine 20 and / or the electric motor 28 to establish the engine speed at the target speed.

[0100] Current speed R c For example, it is determined by the engine control module 72 based on command parameters P1, P2 transmitted by the engine control module 72 to the gas turbine engine 20 and / or the electric motor 28 (open loop operation). c The signals are transmitted via sensors (not shown) of the gas turbine engine 20 to the engine control module 72 (closed loop operation).

[0101] The engine control module 72 is particularly configured to transmit to the gas turbine engine 20 at least one command parameter P1 suitable for stabilizing the engine speed above the idle speed R supplied by the management system 78. r The engine control module 72 is also configured to receive a thrust setpoint C of the aircraft 10 . p , and transmits to the gas turbine engine 20 and / or the electric motor 28 at least one command parameter P1, P2 suitable for accelerating the engine body 36 to a thrust set point C p and the current engine speed R cThe acceleration rate is limited to the maximum acceleration rate T provided by the management system 78. 最大 .

[0102] Thrust set point C p is less than or equal to the full throttle thrust set point. This full throttle thrust set point is intended, in a known manner, to move the fan 60 at a predetermined speed so as to obtain a so-called "full throttle" thrust, which is a function of the flight conditions. This predetermined speed of the fan 60 corresponds to a speed of the engine body 36 that will be referred to as the "full throttle" speed, which is itself a function of the flight conditions. This full throttle speed is marked R in the figure. 油门 When the thrust setting point C p When the thrust setting point is equal to the full throttle thrust setting point, the thrust setting point C p is interpreted by the engine control module 72 as a set point for accelerating the engine 36 to the full throttle speed.

[0103] The first command parameter P1 transmitted to the gas turbine engine 20 is, for example, a set point for metering the fuel to be injected into the combustion chamber 34. The second command parameter P2 transmitted to the electric motor 28 is, for example, a torque set point.

[0104] The engine control module 72 is also configured to calculate the current engine speed R c Transmitted to the management and control system 76.

[0105] The command module 74 is configured to control the power supplied to the electrical system of the aircraft 10 by the rotary machine 22 and the or each auxiliary power source 26. To this end, the command module 74 is configured to determine the current power P generated by the rotary machine 22 c and auxiliary power P supplied by one or more auxiliary power sources 26 a The command module 74 is configured to transmit to the rotary machine 22 and / or the or each auxiliary power source 26 at least one set point C1, C2 suitable for regulating the current power P c and auxiliary power P a .

[0106] Current power P c and auxiliary power P a For example, it is determined by the command module 74 based on the set points C1 , C2 transmitted by the command module 74 to the rotating machine 22 and to the or each auxiliary power source 26 (open loop operation). c and auxiliary power P a The signal is transmitted to the command module 74 via sensors (not shown) located at the rotating machine 22 , at the or each auxiliary power source 26 , and / or at the transmission member 29 (closed loop operation).

[0107] The first set point C1 transmitted to the rotary machine 22 is, for example, a set point for injecting an excitation current into the winding of the rotary machine 22. The second set point C2 transmitted to the auxiliary power source 26 is, for example, a set point for closing a switch connecting the auxiliary power source 26 to the distribution member 29.

[0108] Typically, the command module 74 is configured to receive an item of information I regarding the current power demand of the aircraft 10. C , and transmits at least one set point C1, C2 to the rotating machine 22 and / or the or each auxiliary power source 26, the at least one set point C1, C2 being suitable for making the current power P c and auxiliary power P a The sum of the information items I C Reflected needs.

[0109] In particular, the command module 74 is configured to set the current power P c The maximum power P supplied by the control system 76 is limited to 最大 , and the command module 74 is configured to command the one or more auxiliary power sources 26 so that the one or more auxiliary power sources supplement the power demand of the aircraft 10. In other words, the command module 74 is configured to command the rotary machine 22 so that the current power P generated by the rotary machine c Equal to power P 最大 , or if the current power P c The lower one is equal to the information item I C The command module 74 is configured to command one or more auxiliary power supplies 26 so that when the information item I C The current demand reflected is greater than the power P 最大 When one or more auxiliary power supplies are supplied with the current demand and power P 最大 The difference between the equal auxiliary power P a .

[0110] The command module 74 is configured to apply the current power P in particular when the engine body 36 is in the acceleration phase. c Preferably, the command module 74 is configured to apply the current power P at any time (including when the engine body 36 is not in the acceleration phase). c of this limitation.

[0111] Advantageously, the command module 74 is also configured to convert the current power P c Transmitted to the management system 78.

[0112] The management system 76 is configured to receive a current engine speed R from the engine control module 72.c information item, and from the current engine speed R c Derive the maximum allowable power P 最大 The management and control system 76 is also configured to set the maximum allowable power P 最大 Transmitted to the command module 74.

[0113] In particular, the control system 76 is configured to determine the maximum allowable power P 最大 , so that the following two constraints are observed:

[0114] - When the rotating machine 22 generates the maximum permissible power P 最大 When the engine body 36 changes from the current engine speed R c Accelerate so that within a specified time t less than or equal to 10 seconds (e.g., between 7.5 seconds and 8.5 seconds) i ( Figure 7 ) without stalling to reach the target speed R 目标 ( Figure 7 ), at the target speed R 目标 The gas turbine engine 20 produces a large percentage of full throttle thrust (typically between 89% and 91%), and

[0115] - When the engine body 36 is at the current speed R c The rotating machine 22 generates the maximum allowable power P 最大 When the temperature at the outlet of the gas turbine engine 20 (for example, the outlet of the low-pressure turbine 54) is maintained below the predetermined maximum temperature T° 最高 ( Figure 8 ).

[0116] To this end, the control system 76 is configured to determine the maximum permissible power P 最大 , so that the maximum allowable power is less than or equal to the acceleration limit power and the overheating limit power:

[0117] - For the acceleration limit power, when the rotary machine 22 generates the acceleration limit power, the engine body 36 is increased from the current engine speed R c Accelerate to the stall limit, so that within the specified time t i The target speed R is reached without stalling 目标 ,as well as

[0118] - For the overheat limit power, when the engine body 36 is at the current speed R c When the rotating machine 22 generates the overheat limit power, the temperature of the gas at the outlet of the gas turbine engine 20 is equal to the predetermined maximum temperature T° 最高 .

[0119] In particular, the control system 76 is configured to determine the maximum allowable power P 最大 , so that the maximum allowable power is equal to the minimum value of the acceleration limit power and the overheat limit power.

[0120] To this end, the control system 76 is configured, for example, based on parameters of the gas turbine engine 20 and based on the current engine speed R c To calculate the acceleration limit power and the overheating limit power, and then determine the maximum allowable power P as a function of the limit power 最大 In a variant, the maximum permissible power P respecting these constraints and as a function of the flight conditions has been predetermined for each possible engine speed. 最大 , and the management system 76 is parameterized to associate each possible engine speed with a corresponding maximum allowed power P as a function of the flight conditions. 最大 Associated functions.

[0121] The management system 78 is configured to receive a signal indicating the current power P from the command module 74. c information item, and from the current power P c Derived idle speed R r and the maximum acceleration rate T 最大 The management system 78 is also configured to set the idle speed R r and the maximum acceleration rate T 最大 Sent to the engine control module 72 .

[0122] In particular, the management system 78 is configured to set the maximum acceleration rate T 最大 Limited to be higher than the limit acceleration rate, when the current power P is generated c When the compressor 40 exceeds the limit acceleration rate, it will stall.

[0123] Furthermore, the management system 78 is configured to limit the idle speed R r , so that the following two constraints are observed:

[0124] - The current power P generated by the rotating machine 22 c When the engine body 36 is at idle speed R r Accelerate to the maximum acceleration rate T 最大 , so that at the specified time t i Reach the target speed R without stalling 目标 ,as well as

[0125] - When the engine body 36 is at idle speed R r The rotating machine 22 generates current power P c When the temperature at the outlet of the gas turbine engine 20 (for example, the outlet of the low-pressure turbine 54) is maintained below the predetermined maximum temperature T° 最高 .

[0126] To this end, the management system 78 is configured to determine the idle speed R r , so that the idle speed is greater than or equal to the acceleration limit speed and the overheating limit speed:

[0127] - For the acceleration limit speed, the current power P generated by the rotating machine 22 c When the engine body 36 is accelerated from the acceleration limit speed to the stall limit, the engine body 36 is accelerated from the acceleration limit speed to the stall limit, so that ... i The target speed R is reached without stalling 目标 ,as well as

[0128] - For the overheat limit speed, when the engine body 36 rotates at the overheat limit speed and the rotating machine 22 generates the current power P c When the temperature of the gas at the outlet of the gas turbine engine 20 is equal to the predetermined maximum temperature T° 最高 .

[0129] In particular, the management system 78 is configured to determine the idle speed R r , so that the idle speed is equal to the maximum value of the acceleration limit speed and the overheating limit speed.

[0130] To this end, the management system 78 is configured, for example, to determine the current power P based on the parameters of the gas turbine engine 20 and based on the current power P c To calculate the acceleration limit speed and the overheat limit speed, and then determine the idle speed R as a function of the limit speed r In a variant, the idle speed R , respecting these constraints and as a function of the flight conditions, has been predetermined for each possible power generation. r , and the management system 78 is parameterized to relate each possible generated power to a corresponding idle speed R as a function of flight conditions r Associated functions.

[0131] It is easy to understand that when the engine speed is established at the idle speed R r When the current power P c The maximum allowable power P 最大 .

[0132] The management system 78 is also configured to receive from the aircraft 10 an item of information I representing a future power demand of the aircraft 10. f , and from this information item I f The future power demand of the aircraft 10 is derived. The management system 78 is also configured to modify the idle speed R r In order to make the idle speed meet the future demand, and the idle speed R thus modified r Sent to the engine control module 72 .

[0133] In particular, the management system 78 is configured to c Based only on information item I f Modify idle speed R r (In addition, it should be understood that the management system 78 is also configured to modify the current power P upward or downward. c The function of idle speed R r The management system 78 is configured so that in this case the idle speed R r Increase so that the following two constraints are observed:

[0134] - When the rotary machine 22 generates electric power equal to the future demand, the engine body 36 is increased from the idle speed R r Accelerate to the maximum acceleration rate T 最大 , so that at the specified time t i Reach the target speed R without stalling 目标 ,as well as

[0135] - When the engine body 36 is at idle speed R r When the rotating machine 22 generates electric power equal to the future demand, the temperature at the outlet of the gas turbine engine 20 (for example, the outlet of the low-pressure turbine 54) is kept below the predetermined maximum temperature T°. 最高 .

[0136] To this end, the management system 78 is configured to modify the idle speed R r , so that the idle speed is greater than or equal to the future acceleration limit speed and the future overheating limit speed:

[0137] - For the future acceleration limit speed, when the rotary machine 22 generates electric power equal to the future demand, the engine body 36 is accelerated from the future acceleration limit speed to the stall limit, so that at the prescribed time t i The target speed R is reached without stalling 目标 ,as well as

[0138] - For the future overheat limit speed, when the engine body 36 rotates at the overheat limit speed and the rotary machine 22 generates electric power equal to the future demand, the temperature of the gas at the outlet of the gas turbine engine 20 is equal to the predetermined maximum temperature T° 最高 .

[0139] In particular, the management system 78 is configured to modify the idle speed R r , so that the idle speed is equal to the maximum value of the acceleration limit speed and the overheating limit speed.

[0140] To this end, the management system 78 is configured, for example, to calculate a future acceleration limit speed and a future overheating limit speed based on the parameters of the gas turbine engine 20 and based on future requirements, and then to modify the idle speed R as a function of the future limit speeds. r In a variant, the idle speed R , respecting these constraints and as a function of the flight conditions, has been predetermined for each possible power generation. r , and the management system 78 is parameterized to relate each possible generated power to a corresponding idle speed R as a function of flight conditions r Associated functions.

[0141] It is easy to understand that when the future demand is greater than the maximum allowable power P 最大 When the idle speed R is modified in this way r Increase to a speed greater than the current speed R c Because the engine control module 72 is configured to establish the engine speed to be higher than the idle speed R r , which therefore mechanically drives the acceleration of the engine body 36 .

[0142] The control system 24 (including in particular the engine control module 72, the command module 74, the management system 76, and the management system 78) is typically implemented in the form of a computer program stored in a memory of a processing system (not shown) of the propulsion system 12 and executable by a processor (not shown) associated with the memory. In a variant, the control system 24 is at least partially implemented in the form of a programmable logic component included in the propulsion system 12 or in the form of an application-specific integrated circuit included in the propulsion system 12.

[0143] Now refer to Figure 4 A control method 100 implemented by a propulsion system is described.

[0144] The method 100 includes determining the current power P c During this step 110, the command module 74 determines the current power P generated by the rotating machine 22, for example based on the set points C1, C2 transmitted to the rotating machine 22 or based on items of information transmitted to the command module 74 by sensors (not shown) located at the rotating machine 22 or at the transmission member 29. c (Closed loop operation).

[0145] After step 110, the idle speed R is limited. r Step 120. During this step, the management system 78 defines as the current power P c The function of idle speed R r .

[0146] In the example shown, step 120 includes a first sub-step 122 of calculating the acceleration limit speed, a second sub-step 124 of calculating the overheat limit speed, and assigning a value to the idle speed R r During the first sub-step 122, the management system 78 calculates the current power P c During the second sub-step 124, the management system 78 calculates the acceleration limit speed as a function of the current power P c Finally, during the third sub-step 126, the management system 78 assigns a value greater than or equal to the acceleration limit speed and the overheat limit speed to the idle speed R r Typically, during this sub-step 126, the management system 78 assigns to the idle speed R a value equal to the maximum of the acceleration limit speed and the overheat limit speed. r .

[0147] In a variant (not shown), step 120 consists in assigning a value to the idle speed R r In this variant, during this sub-step 126, the management system 78 assigns a value determined by a function parameterized in the management system 78 to the idle speed R r , the function converts the current power P c and the corresponding idle speed R for given flight conditions r Associated. Figure 5 An example of such a function is given.

[0148] like Figure 5 It can be seen that the engine idle speed R r tends to increase with the current power P c And increase: with the first current power P c1 The associated first engine idle speed R r1 Less than the second current power P c2 (greater than the first current power P c1 ) associated with the second engine idle speed R r2 This is as follows Figures 6 to 8 As easily explained in detail.

[0149] Figure 6 is a flow rate / compression ratio graph showing a characteristic curve of the high-pressure compressor 40 of the gas turbine engine 20 under various conditions. Figure 6 The following is shown:

[0150] - Surge line L of the high pressure compressor 40 p ; As is known to those skilled in the art, this is the line beyond which the high-pressure compressor 40 stalls;

[0151] -Boundary line L of high pressure compressor 40m As is well known to those skilled in the art, this is the line beyond which the risk of stalling the high-pressure compressor 40 is unlikely to comply with aviation safety requirements;

[0152] - When the electric power generated by the rotating machine 22 is equal to the first current electric power P c1 and the second current power P c2 When the operating line Lf of the high pressure compressor 40 is Pc1 and Lf Pc2 As known to those skilled in the art, these operating lines Lf Pc1 and Lf Pc2 It is defined that when the electric power generated by the rotating machine 22 is equal to the first current electric power P c1 and the second current power P c2 When the high pressure compressor 40 has a pair of flow rate-compression ratios for stable operation;

[0153] - The high pressure compressor 40 is at a first engine idle speed R r1 , Second engine idle speed R r2 and full throttle speed R 油门 The constant velocity line Li Rr1 , Li Rr2 and Li R油门 As known to those skilled in the art, these isokinetics Li Rr1 , Li Rr2 and Li R油门 It is defined that when the engine body 36 is at the first engine idle speed R r1 , Second engine idle speed R r2 and full throttle speed R 油门 the flow rate-compression ratio pairs achievable by the high pressure compressor 40 when rotating; and

[0154] -Acceleration transient curve Ta 1-1-1 、 1-1-2 and Ta 2-2-2 , represents the variation of compression ratio as a function of flow rate when:

[0155] ○ When the engine body 36 is at the first engine idle speed R r1 The power generated by the rotary machine 22 when accelerating at the first acceleration rate T1 is equal to the first current power P c1 hour,

[0156] ○ When the engine body 36 is at the first engine idle speed R r1 The power generated by the rotary machine 22 when accelerating at the first acceleration rate T1 is equal to the second current power P c2 When, and

[0157] ○ When the engine body 36 is at the second engine idle speed R r2 The electric power generated by the rotary machine 22 when accelerating at the second acceleration rate T2 which is smaller than the first acceleration rate T1 is equal to the second current electric power P c2 hour.

[0158] at the same time, Figure 7 is a graph showing the engine speed of the engine body 36 as a function of time under different conditions. Figure 7 The following is shown:

[0159] - When the engine body 36 is at the first engine idle speed R r1 The first acceleration curve Ca of the engine body 36 when accelerating at the first acceleration rate T1 1-1 ,

[0160] - When the engine body 36 is at the first engine idle speed R r1 The second acceleration curve Ca of the engine body 36 when accelerating at the second acceleration rate T2 1-2 ,as well as

[0161] - When the engine body 36 is from the second engine idle speed R r2 The third acceleration curve Ca of the engine body 36 when accelerating at the second acceleration rate T2 2-2 .

[0162] like Figure 6 It can be seen that the acceleration transient curve Ta 1-1-1 Partially along the boundary line L m This means that the high-pressure compressor 40 is at the stall limit during the stage of accelerating at the first acceleration rate T1. Therefore, for the first current power P c1 , the first acceleration rate T1 constitutes the maximum acceleration rate T 最大 .like Figure 7 The acceleration curve Ca 1-1 As shown, the acceleration rate T1 does enable the engine body 36 to be driven from the first engine idle speed R r1 Accelerate to achieve the desired result within the specified time t i Reach target speed R within 目标 .

[0163] When the electric power generated by the rotary machine 22 is equal to the second current electric power P c2 If it is desired that the engine body 36 be shifted from the same first engine idle speed R r1 At the same first acceleration rate T1, the compression ratio of the high pressure compressor 40 will follow the acceleration transient curve Ta 1-1-2 However, if Figure 6 It can be seen that the acceleration transient curve Ta 1-1-2 With boundary line L mTherefore, when the electric power generated by the rotating machine 22 is equal to the second current electric power P c2 When the power generated by the rotary machine 22 is equal to the second current power P, accelerating the engine body 36 at the first acceleration rate T1 involves an excessive risk of stalling the high-pressure compressor 40, and therefore the first acceleration rate T1 is unacceptable. c2 When the engine body 36 is accelerated, it is recommended to use a lower acceleration rate, for which the acceleration transient curve is at least partially along the boundary line L m Extending without contacting the boundary line L m Intersection: The lower acceleration rate is composed of a second acceleration rate T2, such as Figure 6 The acceleration transient curve Ta 2-2-2 shown.

[0164] However, if Figure 7 The acceleration curve Ca 1-2 As shown, the engine body 36 is moved from the first engine idle speed R r1 The second acceleration rate T2 cannot accelerate within the specified time t i Reach target speed R within 目标 Therefore, in order to achieve this goal, the engine idle speed R r Increase to the second engine idle speed R r2 ,like Figure 7 The curve Ca 2-2 shown.

[0165] Since the electric power generated by the rotating machine 22 is equal to the second current electric power P c2 , so the second engine idle speed R r2 Must be greater than the first engine idle speed R r1 , so that the engine body 36 can be i Reach the target speed R without stalling 目标 .

[0166] Second engine idle speed R r2 It must also be greater than the first engine idle speed R r1 To prevent the exhaust gas temperature at the outlet of the gas turbine engine 20 from exceeding the maximum temperature T° 最高 , as will be read in Figure 8 understood at the time.

[0167] Figure 8 Specifically, it is a graph showing the relationship between the temperature at the outlet of the gas turbine engine 20 and the engine speed of the engine body 36 under different conditions. Figure 8 The following is shown:

[0168] - When the electric power generated by the rotating machine 22 is equal to the first current electric power P c1 The first temperature curve T at the outlet of the gas turbine engine 20 is Pc1 ,as well as

[0169] - When the electric power generated by the rotating machine 22 is equal to the second current electric power P c2 The second temperature curve T at the outlet of the gas turbine engine 20 is Pc2 .

[0170] like Figure 8 It can be seen that the first temperature curve T Pc1 and the second temperature curve T Pc2 Each has a U-shaped profile, idling R r The range of variation of is located in the region where these curves of the curve diagram descend. r1 When the engine body 36 is at the idle speed R r1 The electric power generated by the rotating machine 22 is equal to the first current electric power P c1 When the temperature at the outlet of the gas turbine engine 20 is equal to the maximum temperature T° 最高 Finally, the second temperature curve T Pc2 Logically located at the first temperature curve T Pc1 Because for the same engine speed, supplying mechanical energy to the rotating machine 22 requires burning more combustible material in the combustion chamber 34. This requires that if the power generated by the rotating machine 22 is equal to the second current power P c2 When the engine body 36 is at the first idle speed R r1 Rotation, the temperature at the outlet of the gas turbine engine 20 will be greater than the maximum temperature T° 最高 The value of T° 更高 To avoid this, select a higher second engine idle speed R r2 , the second engine idle speed R r2 is composed of a minimum engine speed for which the electric power generated by the rotary machine 22 is equal to the second current electric power P c2 When the temperature at the outlet of the gas turbine engine 20 is less than or equal to the maximum temperature T° 最高 .

[0171] Return to Figure 4 After step 120, a speed higher than the idle speed R is established. r During this step 130, the engine control module 72 sends at least one command parameter P1, P2 to the gas turbine engine 20 and optionally to the electric motor 28, so that the engine speed of the engine body 36 is established at a speed greater than or equal to the idle speed R rThe current engine speed R c For example, during this step 130, the engine speed is established at the engine idle speed R r This is typically the case when aircraft 10 requires minimal propulsion from propulsion system 12, such as during parking on a runway or during a descent.

[0172] The control method 100 also includes determining the current engine speed R c During this step 140, the engine control module 72 determines the current engine speed R based on one or more command parameters P1, P2 transmitted to the gas turbine engine 20 and / or the electric motor 28 (open loop operation) or based on items of information transmitted by sensors (not shown) of the gas turbine engine 20 (closed loop operation). c .

[0173] This step 140 is followed by defining the maximum permissible power P 最大 Step 150. During this step, the control system 76 defines as the current engine speed R c The maximum permissible power P as a function of 最大 .

[0174] In the example shown, step 150 includes a first sub-step 152 of calculating the acceleration limit power, a second sub-step 154 ​​of calculating the overheat limit power, and assigning a value to the maximum allowable power P 最大 During the first sub-step 152, the control system 76 calculates the current engine speed R c During the second sub-step 154, the control system 76 calculates the current engine speed R c Finally, during the third sub-step 156, the management and control system 76 assigns a value less than or equal to the acceleration limit power and the overheat limit power to the maximum allowable power P 最大 Typically, during this sub-step 156, the management and control system 76 assigns to the maximum allowable power P a value equal to the maximum value of the acceleration limit power and the overheat limit power. 最大 .

[0175] In a variant (not shown), step 150 consists in assigning a value to the maximum allowed power P 最大 In this variant, during this sub-step 156, the control system 76 assigns to the maximum permitted power P a value determined by a function parameterized in the control system 76. 最大 , the function converts the current engine speed R c and the corresponding maximum permissible power P for a given flight condition 最大 Associated. Fig. 9 An example of such a function is given.

[0176] As can be seen from the figure, the maximum allowable power P 最大 tends to increase with the current engine speed R c And increase: with the first current speed R c1 The first maximum allowed power P 最大1 Less than the second current speed R c2 (greater than the first current speed R c1 ) The second maximum allowable power P associated with 最大2 This can be seen as follows Figures 10 to 12 As easily explained in detail.

[0177] Fig.10 is a graph showing the engine speed of the engine body 36 as a function of time under different conditions. Fig.10 The following is shown:

[0178] - When the engine body 36 changes from the first current engine speed R c1 The first acceleration curve Ca′ of the engine body 36 when accelerating at the first acceleration rate T1 1-1 ,

[0179] - When the engine body 36 changes from the first current engine speed R c1 The second acceleration curve Ca′ of the engine body 36 when accelerating at the second acceleration rate T2 which is smaller than the first acceleration rate T1 1-2 ,as well as

[0180] - When the engine body 36 changes from the second current engine speed R c2 The third acceleration curve Ca′ of the engine body 36 when accelerating at the second acceleration rate T2 2-2 .

[0181] For example, the third acceleration curve Ca' 2-2 As shown, the second acceleration rate T2 is sufficient to make the engine body 36 c2 During acceleration, the engine body 36 can i Reach target speed R within 目标 On the other hand, as shown in the second acceleration curve Ca' 1-2 As shown, the second acceleration rate T2 is insufficient to make the engine body 36 decrease from the first current speed R c1 During acceleration, the engine body 36 can i Reach target speed R within 目标 . For example, the first acceleration curve Ca' 1-1 As shown, in order to change the engine body 36 from the first current speed R c1During acceleration, the engine body 36 is able to i Reach target speed R within 目标 , the engine body 36 must be accelerated at a first acceleration rate T1.

[0182] Fig.11 is a flow rate / compression ratio graph showing a characteristic curve of the high-pressure compressor 40 of the gas turbine engine 20 under various conditions. Fig.11 The following is shown:

[0183] - Surge line L of the high pressure compressor 40 P ;

[0184] -Boundary line L of high pressure compressor 40 m ;

[0185] - When the electric power generated by the rotating machine 22 is equal to the first maximum allowable electric power P 最大1 and the second maximum permissible power P 最大2 When the operating line Lf of the high pressure compressor 40 is P最大1 and Lf P最大2 ;

[0186] The high-pressure compressor 40 is at a first current engine speed R c1 , the second current engine speed R c2 and full throttle speed R 油门 The constant velocity line Li Rc1 , Li Rc2 and Li R油门 ;as well as

[0187] -Acceleration transient curve Ta' 1-1-1 、Ta' 1-1-2 and Ta' 2-2-2 , shows the variation of compression ratio as a function of flow rate when:

[0188] ○ When the engine body 36 changes from the first current engine speed R c1 The power generated by the rotary machine 22 when accelerating at the first acceleration rate T1 is equal to the first maximum allowable power P 最大1 hour,

[0189] ○ When the engine body 36 changes from the first current engine speed R c1 The power generated by the rotary machine 22 when accelerating at the first acceleration rate T1 is equal to the second maximum allowable power P 最大2 When, and

[0190] ○ When the engine body 36 changes from the second current engine speed R c2 The power generated by the rotary machine 22 at the second acceleration rate T2 is equal to the second maximum allowable power P最大2 hour.

[0191] Such as the acceleration transient curve Ta' 2-2-2 As shown, when the engine body 36 changes from the second current speed R c2 The power generated by the rotary machine 22 at the second acceleration rate T2 is equal to the second maximum allowable power P 最大2 When the compression ratio of the high pressure compressor 40 is kept above the boundary line L m : Therefore, there is no risk of stalling of the compressor 40. On the other hand, as shown in the acceleration transient curve Ta' 1-1-2 As shown, if the engine body 36 is expected to change from the first current speed R c1 The power generated by the rotary machine 22 while accelerating at the first acceleration rate T1 is still equal to the second maximum allowable power P 最大2 , the compression ratio of the high-pressure compressor 40 exceeds the boundary line L m : This brings an excessive risk of stalling the high-pressure compressor 40, so the maximum allowed power is maintained at the value P when the first acceleration rate T1 is applied. 最大2 is unacceptable. In order to be able to apply the first acceleration rate T1, and therefore in order to make the engine body 36 from the first current speed R c1 The power generated by the rotating machine 22 is equal to the maximum allowable power P 最大 The engine body 36 can be i Reach target speed R within 目标 , then the maximum allowable power P 最大 must be reduced to a lower value P 最大1 , such as the acceleration transient curve Ta' 1-1-1 shown.

[0192] Therefore, the first maximum allowable power P 最大1 must be less than the second maximum allowable power P 最大2 , so that when the engine body 36 is at the first current engine speed R c1 When rotating, the engine body 36 can i Reach the target speed R without stalling 目标 .

[0193] The first maximum permissible power P 最大1 Less than the second maximum allowable power P 最大2 Another reason is Fig.12 This figure is a graph showing the relationship between the temperature at the outlet of the gas turbine engine 20 and the engine speed of the engine body 36 under different conditions. Fig.12 The following is shown:

[0194] - When the electric power generated by the rotating machine 22 is equal to the first maximum permissible electric power P 最大1 The first temperature curve T at the outlet of the gas turbine engine 20 is P最大1 ,as well as

[0195] - When the electric power generated by the rotating machine 22 is equal to the second maximum permissible electric power P 最大2 The second temperature curve T at the outlet of the gas turbine engine 20 is P最大2 .

[0196] like Fig.12 It can be seen that the first temperature curve T P最大1 and the second temperature curve T P最大2 Each has a U-shaped profile, the current engine speed R c The range of variation of is located in the region where these curves of the curve diagram descend. In addition, the second current engine speed R c2 When the engine body 36 is at the second current engine speed R c2 The electric power generated by the rotating machine 22 is equal to the second maximum allowable electric power P 最大2 When the temperature at the outlet of the gas turbine engine 20 is equal to the maximum temperature T° 最高 Finally, the second temperature curve T P最大2 Logically located at the first temperature curve T P最大1 Because for the same engine speed, supplying mechanical energy to the rotating machine 22 requires burning more combustible material in the combustion chamber 34. This requires that if the engine body 36 is at the first current engine speed R c1 The rotating machine 22 is capable of generating a second maximum allowable power P when rotating. 最大2 , then the temperature at the outlet of the gas turbine engine 20 will be greater than the maximum temperature T° 最高 The value of T° 更高 To avoid this situation, when the engine body 36 is at the first current engine speed R c1 Maximum allowable power during rotation P 最大 is set to a lower value P 最大2 , the value consists of the maximum power generated, for which the maximum power generated when the engine body 36 is at the first current engine speed R c1 When rotating, the temperature at the outlet of the gas turbine engine 20 is less than or equal to the maximum temperature T° 最高 .

[0197] It can be easily seen that Figure 5 and Fig. 9 The curves are overlapped. Therefore, given as the current speed R c The maximum permissible power P as a function of 最大 The curve is given as the current power Pc The function of idle speed R r This means that, as in the example detailed here, when the engine speed is established at the idle speed R r In other words, when the idle speed R r The current engine speed R c When the current power P c The maximum allowable power P 最大 .

[0198] Step 150 is followed by limiting the generated power to the maximum allowed power P 最大 During this step 150, the command module 74 limits the power generated by the rotating machine 22 to the maximum allowed power P 最大 Specifically, the command module 74 commands the rotating machine 22 so that the current power P generated by the rotating machine 22 is c Equal to power P 最大 , or if the power P 最大 is lower, the current power P generated by the rotating machine 22 c = equal to the information item I of aircraft 10 C The command module 74 controls the engine body 36 to operate at the current engine speed R c This limitation is applied during rotation and during any subsequent acceleration phase until the engine speed stabilizes at the new value.

[0199] After step 160, the control method 100 further comprises a step 170 of controlling the variation of the electric power generated by the rotary machine 22. These variations of electric power are limited to a maximum allowed electric power P 最大 If the generated power changes, the control method 100 returns to step 110. Otherwise, the control method 100 continues.

[0200] According to a first variant of the control method 100 , the step following this step 170 is to increase the thrust setpoint C p During this step 180 , the engine control module 72 receives the increased thrust setpoint C from the aircraft 10 . p This step 180 is followed by a step 182 of accelerating the engine block 36, which will be described in detail below.

[0201] According to a second variant of the method 100 for continuing control, this step 170 is followed by a step 190 of deriving the future demand of the aircraft 10. During this step 190, the management system 78 receives from the aircraft 10 an item of information I representing the future power demand of the aircraft 10. f , and from this information item I fThe future power requirements of the aircraft 10 are derived.

[0202] This step 190 is followed by comparing the future demand with the current power P c A comparison step 192 is performed. During this step 192, the management system 78 will be composed of information items I f Reflecting future demand and current electricity P c If the future demand is less than or equal to the current power P c , the method returns to step 160. On the contrary, if the future demand is greater than the current power P c , then after step 192, the idle speed R is modified r So that the idle speed R r Steps to meet future needs194.

[0203] During step 194, the management system 78 modifies the f Idle speed R as a function of future demand r To this end, the management system 78 calculates, for example, the future acceleration speed limit and the future overheating speed limit as a function of the future demand, and assigns a new value greater than or equal to the future acceleration speed limit and the future overheating speed limit (usually equal to the maximum of the two future speed limits) to the idle speed R. r In a variant, the management system 78 will be configured to calculate the current power P c The corresponding idle speed R parameterized in the management system 78 r The associated function ( Figure 5 ) determines the new value to be assigned to the idle speed R r The management system 78 then transmits this new value to the engine control module 72 .

[0204] After step 194, the idle speed R r The new value is equal to the current engine speed R c Step 196 of the comparison is performed. During this step 196, the engine control module 72 receives the idle speed R from the management system 78. r The new value is equal to the current engine speed R c If the new value is less than or equal to the current engine speed R c , the method 100 returns to step 130. On the contrary, if the new value is greater than the current engine speed R c , then after step 196 is step 182 of accelerating the engine body 36 .

[0205] During a step 182 , the engine control module 72 sends to the gas turbine engine 20 at least one command parameter P1 suitable for accelerating the engine body 36 . The engine body 36 then increases from the current engine speed R c acceleration, while the rotating machine 22 generates less than or equal to the maximum allowable power P 最大 of power until the new current engine speed R is reached c .

[0206] If step 182 continues from step 196, the new current speed R c By the new engine idle speed R r composition.

[0207] If step 182 continues from step 180 and if the command parameter C is increased p The maximum acceleration rate T 最大 Accelerate. Current engine speed R c Greater than or equal to idle speed R r And the power generated by the rotating machine 22 is limited to the maximum allowable power P 最大 , then the engine body 36 is at a specified time t i Reach the target speed R without stalling 目标 .

[0208] Note that the maximum allowable power P 最大 is the current speed R before step 180 starts c , and is not updated during step 182 (ie, during the entire acceleration phase 182), the maximum allowed power P 最大 Remain constant at the following value: The value depends on the current speed R before acceleration c .

[0209] Control method 100 then returns to step 130 .

[0210] Optionally, step 182 comprises a sub-step 184 of injecting electric power by the electric motor 28. During this step 184, the engine control module 72 sends to the electric motor 28 at least one command parameter P2 suitable for increasing the torque of the electric motor 28. Thus, the electric motor 28 injects mechanical energy into the high-pressure shaft 44 and contributes to the acceleration of the engine body 36. This makes it possible to increase the maximum acceleration rate T for a given generated electric power. 最大 Therefore, it is possible to reduce the current power P c The associated engine idle speed R r and can be increased with the current engine speed R c The associated maximum power P 最大 .

[0211] Due to the above exemplary embodiment, the engine idle speed R r can be adjusted as a function of the power actually produced by the rotating machine 22. Thus, the engine idle speed R r The engine speed is reduced to below the minimum required to withstand the maximum power that can be generated by the rotary machine 22. As a result, the thrust of the propulsion system 12 at idle speed can be reduced. This enables the ratio of the drag of the aircraft 10 to the thrust of the propulsion system 12 at engine idle speed to be maintained at a sufficiently high value so that the descent gradient of the aircraft 10 is not too low. Therefore, it is not necessary to perform descent maneuvers that destroy the lift of the aircraft or increase the drag of the aircraft, which makes it possible to save fuel. Similarly, on the ground, the engine idle speed R r The reduction of makes it possible to reduce the wear on the brakes of the aircraft 10.

Claims

1. An aircraft propulsion system (12), the aircraft propulsion system comprising a gas turbine engine (20) having a combustion chamber (34) and an engine body (36), the engine body (36) comprising a turbine (42) located downstream of the combustion chamber (34), a compressor (40) located upstream of the combustion chamber (34), and a drive shaft (44) for driving the compressor (40) via the turbine (42), the propulsion system (12) further comprising a control system (24), a system for determining a current engine speed (R) of the engine body (36), c ), and a rotating machine (22) coupled to the transmission shaft (44) for generating electricity by extracting mechanical power from the transmission shaft (44), in, The control system (24) is configured to control the current power (P) generated by the rotary machine (22) at least when the engine body (36) is in an acceleration phase. c ) is limited to the maximum allowable power (P 最大 ), the maximum allowable power is the current engine speed before acceleration (R c ), and wherein the propulsion system (12) comprises a method for determining the current power (P c ) device (74), the control system (24) being configured to establish the engine speed to be higher than the idle speed (R r ), the idle speed is the current power (P c ) function.

2. The propulsion system (12) of claim 1, comprising a system (78) for deriving a future demand of the aircraft for the electric power generated by the rotary machine (22), the control system (24) being configured to: 最大 ) when accelerating the engine body (36).

3. The propulsion system (12) according to claim 1 or 2, wherein: When the engine speed is established at the idle speed (R r ), the current power (P c ) constitutes the maximum allowable power (P 最大 ).

4. The propulsion system (12) according to any one of claims 1 to 3, wherein: The idle speed (R r ) is greater than or equal to the acceleration limit speed, for which the current power (P c ), the engine body (36) is accelerated from the acceleration limit speed to the stall limit, so that the engine body is accelerated within a prescribed time (t i ) without stalling to reach the target speed (R 目标 ), at which target speed, the gas turbine engine (20) produces a large percentage of full throttle thrust.

5. The propulsion system (12) according to any one of claims 1 to 4, wherein: The idle speed (R r ) is greater than or equal to the overheat limit speed, for which, when the engine body (36) rotates at the overheat limit speed and the rotary machine (22) generates the current power (P c ), the temperature of the gas at the outlet of the gas turbine engine (20) is equal to a predetermined maximum temperature (T 最大 ).

6. The propulsion system (12) according to claims 4 and 5, wherein: The idle speed (R r ) is equal to the maximum value of the acceleration limit speed and the overheating limit speed.

7. The propulsion system (12) according to any one of claims 1 to 6, wherein: The maximum allowable power (P 最大 ) is less than or equal to the acceleration limit power, for which the acceleration limit power is generated in the rotating machine (22) 最大 ), the engine body (36) changes from the current engine speed (R c ) is accelerated to the stall limit, so that the engine body is less than or equal to 10 seconds in a prescribed time (t i ) without stalling to reach the target speed (R 目标 ), at which target speed, the gas turbine engine (20) produces a large percentage of full throttle thrust.

8. The propulsion system (12) according to any one of claims 1 to 7, wherein: The maximum allowable power (P 最大 ) is less than or equal to the overheat limit power, for which, when the engine body (36) is at the current speed (R c ) rotates and the rotary machine (22) generates the overheat limit power, the temperature of the gas at the outlet of the gas turbine engine (20) is equal to the predetermined maximum temperature (T 最大 ).

9. The propulsion system (12) according to claims 7 and 8, wherein: The maximum allowable power (P 最大 ) is equal to the minimum value of the acceleration limit power and the overheat limit power.

10. The propulsion system (12) according to any one of claims 1 to 9, wherein: The control system (24) is configured to limit the power generated by the rotary machine (22) when the engine body (36) is not in the acceleration phase.

11. A method (100) for controlling an aircraft propulsion system (12), the propulsion system (12) comprising a gas turbine engine (20) having a combustion chamber (34) and an engine body (36), the engine body (36) comprising a turbine (42) located downstream of the combustion chamber (34), a compressor (40) located upstream of the combustion chamber (34), and a transmission shaft (44) for driving the compressor (40) via the turbine (42), the propulsion system (12) further comprising a rotary machine (22) coupled to the transmission shaft (44) for generating electrical power by extracting mechanical power from the transmission shaft (44), the control method (100) comprising the following consecutive steps: - determining (110) the current power (P) produced by the rotating machine (22) c ), - define (120) as the current power (P c ) is a function of the idle speed (R r ), - Establishing (130) a speed above the idle speed (R r ) of the engine speed, - determining (140) the current engine speed (R) of the engine body (36); c ), - defining (150) as the current engine speed (R c ) is a function of the maximum allowable power (P 最大 ),as well as - accelerating (180) the engine body (36) to convert the current power (P c ) is limited to the maximum allowable power (P 最大 ).

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