Device for controlling the thrust transients of a turbomachine

Abstract

Device (200) for generating a fuel flow rate command (WFC) for a turbomachine (290) comprising low-pressure and high-pressure spools, the device comprising: - a first, steady-state speed, regulating module (210) configured to determine said command (dWF) as a function of a difference between setpoint (N1 setpoint) and operating (N1) parameters of the turbomachine; - a second, low-pressure spool speed-transients, regulating module (220) configured to determine said command (dWFaccel) as a function of a difference between the speed (N1) and a speed setpoint of the low-pressure spool; and - a third, low-pressure spool speed-transients, regulating module (230) configured to determine said command (dWFdecel) as a function of a difference between the speed of the spool (N1) and a speed setpoint for the low-pressure spool.

Description

[0001] Description

[0002] Title of the invention: Device for controlling the thrust transients of a turbomachine

[0003] Technical Field

[0004] The present invention relates to the general field of turbomachines, and more particularly to the control of engine fuel flow.

[0005] Prior art

[0006] In an aircraft engine, it is known to determine a fuel flow setpoint intended for a fuel metering device of a turbomachine as a function of a difference between the speed of the turbomachine and a setpoint speed dependent on a position of a control lever that can be manipulated by the pilot. For this purpose, regulation is implemented by an engine control unit, for example in the electronic engine controller (EEC).

[0007] To protect the engine against the risk of pumping during acceleration or the risk of flameout during deceleration, the control system may include two stops, called C / P pumping and flameout stops, which limit the maximum fuel flow that can be injected during acceleration and the minimum fuel flow that can be injected during deceleration. Under these conditions, the acceleration or deceleration time of an engine depends directly on the pumping margin and the flameout margin of the engine.

[0008] Thus, an aged engine will have a longer acceleration or deceleration time than a new engine. In addition, operating conditions (atmospheric conditions, flight envelope, power draw, etc.) influence acceleration or deceleration times. This results in a lack of reproducibility of acceleration or deceleration times for a given engine, but also a lack of concordance between several engines of the same type, which can lead to thrust asymmetry during a transient request such as acceleration.

[0009] To protect the engine against the risk of pumping during speed transients, regulation can be based on compliance with an acceleration setpoint. However, it is not possible to ensure reproducibility of acceleration and deceleration times. Indeed, monitoring a speed derivative does not make it possible to make up for a delay at the start of a transient.

[0010] Document US 2013 / 0008171 makes it possible to control the acceleration and deceleration transients of a turbojet engine using high pressure (N2) trajectory control loops. However, the disadvantage of controlling the high pressure (HP) trajectory is that it does not allow precise control of the fan rotation speed (or low pressure (LP) spool speed, known as NI), which constitutes the main source of thrust generation for a turbojet engine. This is particularly the case for applications on turbojet engines with a high bypass ratio, where there is a significant phase shift and dispersion between the NI and N2 speeds linked to the disproportion of the inertia of the HP spool compared to the fan. This makes the control of thrust build-up times imprecise when controlling the speed transients by imposing N2 speed trajectories.

[0011] Statement of the invention

[0012] The main aim of the present invention is therefore to overcome the drawbacks of the aforementioned prior art, and more particularly to propose a device for generating a fuel flow control for a turbomachine respecting the acceleration and deceleration times while taking into account the risks of pumping during acceleration (in particular of the high pressure compressor) and of extinction during deceleration.

[0013] This aim is achieved by means of a device for generating a fuel flow command for a turbomachine configured to propel an aircraft and comprising a low-pressure body and a high-pressure body, the device comprising: - a first stationary speed regulation module configured to determine the fuel flow command as a function of a difference between a setpoint parameter dependent on a position of a thrust control lever and an operating parameter of the turbomachine representative of the thrust developed by the turbomachine;

[0014] - a second low pressure spool speed transient regulation module configured to determine the fuel flow control as a function of a difference between the low pressure spool speed and a low pressure spool speed setpoint varying over time according to a trajectory of the low pressure spool speed generated in a predetermined manner during acceleration of the turbomachine, in order to satisfy a need for evolution of the thrust during acceleration; and

[0015] - a third low pressure spool speed transient regulation module configured to determine the fuel flow control as a function of a difference between the low pressure spool speed and a low pressure spool speed setpoint varying over time according to a low pressure speed trajectory generated in a predetermined manner during deceleration of the turbomachine, in order to satisfy a need for evolution of the thrust during deceleration.

[0016] The operating parameter and the associated setpoint parameter correspond to a parameter whose value is linked to the engine thrust.

[0017] The two transient regulation modules based on the low-pressure spool speed make it possible to ensure the deceleration and acceleration times required by the turbomachine while using a parameter more representative of the thrust than the high-pressure spool speed used in US 2013 / 0008171. In particular, the first regulation module makes it possible to satisfy the thrust command; the second regulation module makes it possible to ensure the acceleration time of the engine during thrust; and the third regulation module makes it possible to ensure the deceleration time of the engine during thrust. According to a particular characteristic of the invention, the device also comprises:

[0018] - a first fuel flow saturation module configured to determine a maximum fuel flow and for the fuel flow command to be less than the maximum fuel flow;

[0019] - a second fuel flow saturation module configured to determine a minimum fuel flow and to cause the fuel flow command to be greater than a minimum fuel flow; and

[0020] - a fourth regulation module configured to determine a correction quantity for the fuel flow control from a setpoint derivative of the high pressure body speed.

[0021] The first saturation module protects the high pressure compressor from the high pressure body from surging during engine acceleration.

[0022] The second saturation module protects the motor from turning off during deceleration.

[0023] The fourth regulation module allows more fuel to be dosed than the maximum limit from the C / P pumping stop to limit excessive saturation effects.

[0024] According to another particular characteristic of the invention, the device comprises a fifth regulation module for determining a correction quantity for the fuel flow control by integrating a setpoint of the derivative of the speed of the high pressure body during deceleration or acceleration of the turbomachine.

[0025] The fifth control module protects the low pressure compressor of the low pressure body from surging during engine deceleration.

[0026] According to another particular characteristic of the invention, the device comprises a sixth regulation module configured to determine a correction quantity for the fuel flow control as a function of the minimum speed of the high pressure body. The sixth regulation module makes it possible to control the engine at idle.

[0027] According to another particular characteristic of the invention, the operating parameter and the associated setpoint parameter of the first regulation module is the regime of the low pressure body.

[0028] According to another particular characteristic of the invention, the operating parameter and the associated setpoint parameter of the first regulation module is an engine pressure ratio.

[0029] Another object of the invention is a method for controlling an engine implemented by the generation device according to the invention, in which a fuel flow control is determined, the method comprising:

[0030] - a regulation for stationary regime in which the fuel flow control is determined as a function of a difference between a setpoint parameter dependent on a position of a control lever and an operating parameter of the engine;

[0031] - detection of a regime transient intention; and

[0032] - in response to the detection, a speed transient control in which the fuel flow control is determined as a function of a difference between a low pressure body speed and a predetermined generated time-varying low pressure body speed setpoint.

[0033] The step of detecting an intention of a regime transient may include comparing a difference between the setpoint parameter and the operating parameter with a predetermined threshold. This makes it possible to detect in a simple and efficient manner an intention of a regime transient, before the variation of the regime.

[0034] Transient regulation is therefore implemented during speed transients. Being based on tracking the fan speed trajectory, it makes it possible to improve the reproducibility of acceleration and deceleration times in thrust. Yet another subject of the invention is a turbomachine comprising a device for generating a fuel flow control according to the invention configured to implement the method according to the invention.

[0035] Brief description of the drawings

[0036] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not limiting in nature.

[0037] [Fig. 1] Figure 1 shows, schematically and partially, a longitudinal section of a part of an aircraft turbomachine according to an embodiment of the invention.

[0038] [Fig. 2] Figure 2 shows, schematically and partially, a device for generating a fuel flow control for a turbomachine according to one embodiment of the invention.

[0039] [Fig. 3] Figure 3 shows, schematically and partially, a device for generating a fuel flow control of a turbomachine according to another embodiment of the invention.

[0040] [Fig. 4] Figure 4 shows, schematically and partially, a device for generating a fuel flow control of a turbomachine according to another embodiment of the invention.

[0041] [Fig. 5] Figure 5 schematically represents the method of controlling a turbomachine according to one embodiment of the invention.

[0042] Description of the embodiments

[0043] Figure 1 schematically and partially represents a longitudinal section of an aircraft turbomachine 100 of the double-flow and double-spool turbojet type to which the invention applies in particular. The invention is not limited to this particular type of aircraft engine. In a known manner, the turbomachine 100 of longitudinal axis XX comprises a fan 142 which delivers an air flow into a primary flow duct 144 and into a secondary flow duct 146 coaxial with the primary flow duct 144. From upstream to downstream in the direction of flow of the gas flow passing through it, the primary flow duct 144 comprises a low-pressure compressor 148, a high-pressure compressor 150, a combustion chamber 152, a high-pressure turbine 154 and a low-pressure turbine 156.The low-pressure compressor 148 and the low-pressure turbine 156 form the low-pressure body of the turbomachine 100; and the high-pressure compressor 150 and the high-pressure turbine 154 form the high-pressure body of the turbomachine 100.

[0044] The operation of the engine, in particular the fuel flow control of the engine, is controlled by a WFC fuel flow command generation device 200 shown in FIG. 2. When the device 200 has determined the WFC fuel flow command, it then controls the injection of fuel into the turbomachine (also called in the description engine) 290 according to the determined WFC command.

[0045] This device 200 comprises a first stationary speed regulation module 210 configured to determine the fuel flow WFC command as a function of the difference between the setpoint parameter NI setpoint which depends on the position of the thrust control lever 212 and the operating parameter NI of the turbomachine representative of the thrust developed by the turbomachine. In this example, the setpoint parameter NI setpoint and the operating parameter NI correspond to the speed of the low pressure body, these two parameters correspond to the engine pressure ratio EPR (or “Engine Pressure Ratio” in English).

[0046] Device 200 also includes:

[0047] - a second low pressure body speed transient regulation module 220 configured to determine the fuel flow control WFC as a function of the difference between the low pressure body speed NI and the low pressure body speed setpoint varying over time according to the trajectory of the low pressure body speed generated in a predetermined manner during acceleration of the turbomachine; and

[0048] - a third low pressure body speed transient regulation module 230 configured to determine the fuel flow control WFC as a function of the difference between the low pressure body speed NI and the low pressure body speed setpoint varying over time according to the trajectory of the low pressure body speed generated in a predetermined manner during the deceleration of the turbomachine.

[0049] The second regulation module 220 thus makes it possible to satisfy the need for evolution of the thrust of the engine 290 during acceleration; while the third regulation module 230 makes it possible to satisfy the need for evolution of the thrust of the engine 290 during deceleration.

[0050] In order to detect the transient intention TopAccel and TopDecel desired by the pilot, that is to say to detect an intention of acceleration TopAccel or deceleration TopDecel, the device 200 comprises the modules 221 and 231 for detecting transient intention. When the control lever 212 remains in a constant position and the first regulation module 210 for stationary speed is implemented, the speed NI of the engine 290 is stationary and equal to the set speed NI setpoint. If the pilot moves the lever 212, the set speed NI setpoint varies instantaneously. On the contrary, the speed NI does not vary instantaneously due to the inertia of the engine 290 and the first regulation module 210.

[0051] Thus, the two modules 221 and 231 respectively detect an intention of TopAccel acceleration transient or TopDecel deceleration depending on the difference between the speed of the low pressure body NI and a speed setpoint.

[0052] Then, the two modules 220 and 230 develop the fuel flow variation setpoints dWFAccel and dWFDecel, i.e. the fuel flow delta values ​​dWFAccel and dWFDecel allowing, after integration in the module 214, to follow the acceleration and deceleration trajectories in thrust as reproducibly as possible. Thus, the calculation of the setpoint trajectory is established in such a way as to allow, via the two regulation modules 220 and 230, to impose a fuel flow allowing the thrust to be respected at all points of the acceleration and deceleration by controlling the NI speed of the low-pressure body.

[0053] The device 200 may also comprise two fuel flow saturation modules 240, 250, respectively allowing the engine 290 to shut down during deceleration and protecting the high pressure compressor from surging during acceleration.

[0054] The first saturation module 240 is configured to determine the maximum fuel flow WFmax and to cause the fuel flow command WFC to be less than the maximum flow WFmax. It protects the high pressure compressor from surge under acceleration.

[0055] The second saturation module 250 is configured to determine the minimum fuel flow WFmin and to cause the fuel flow command WFC to be greater than the minimum flow WFmin. It protects the engine 290 from flameout during deceleration.

[0056] The first steady-state regulation module 210 may in particular comprise a summation module 215, a correction network 211, one or more selection modules 213 and an integration module 214.

[0057] The summing module 215 determines the difference between the engine setpoint parameter NI setpoint and the setpoint speed NI (also called the thrust control parameter). The setpoint speed is proportional to the position of the control lever 212 which can be manipulated by the pilot.

[0058] The correction network 211 provides a correction quantity dWF to the selection module(s) 213. The correction network 211 is for example a phase advance filter type corrector.

[0059] The selection module(s) 213 select(s) the correction quantity coming from the correction network 211 or another correction quantity coming from the second 220 or third 230 low pressure body speed transient regulation modules. Then the selected quantity is supplied to the integration module 214 which determines the fuel flow setpoint WFC by integrating the correction quantity dWFC.

[0060] The first 240 and second 250 saturation modules make it possible to provide the integration module 214 with the maximum WFmax and minimum WFmin values ​​of the fuel flow rate by implementing a stop, called a C / P stop. This type of stop is known to those skilled in the art, and it is simply recalled that the minimum WFmin and maximum WFmax stops are expressed, for example, in the form:

[0061] WFmax = -max(N2, T25, PT, ... ) ■ Ps32 ■ P v 7 X 288.115

[0062] WFmin = -min( / V2, T25, PT, ... ) ■ Ps32 ■

[0063] P v 7 288.115 with T25, the temperature at the outlet of the low pressure compressor; Ps32, the static pressure in the combustion chamber.

[0064] Figure 3 represents a second embodiment of the device 300 for generating a WFC fuel flow command of a turbomachine engine 390. Compared to the device 200 of Figure 2, the device 300 of Figure 3 comprises a fourth 360 and a fifth 370 regulation modules, in addition to the first 310, second 320, third 330 regulation modules, the first 340 and second 350 saturation modules, and the transient intention detection modules 321 and 331 as described above.

[0065] The fourth regulation module 360 ​​is configured to determine a correction quantity WF dn / dt min of the fuel flow control from a high pressure body N2 speed derivative setpoint, dN2 / dt. This regulation makes it possible to inject more fuel than the WFmax limit from the first saturation module 340 to limit abusive saturation effects and avoid engine stagnation in the event of an erroneous C / P stop. The derivative setpoint dN2 / dt min may be a function of certain parameters, such as the high pressure body N2 speed, the temperature T25 at the outlet of the low pressure compressor, the pressure PT at the inlet of the blower, or any other parameter making it possible to characterize the acceleration capabilities of the engine 390 in dN2 / dt.

[0066] The fifth control module 370 is configured to determine a correction quantity dWF32decel of the fuel flow control by integrating a derivative setpoint dN2 / dt decel of the speed of the high pressure spool during deceleration or acceleration of the turbomachine. This control makes it possible in particular to protect the low pressure compressor from surge during excessively rapid deceleration of the high pressure spool from the point of view of the surge margin of the low pressure compressor.

[0067] Figure 4 represents a third embodiment of the device 400 for generating a WFC fuel flow control of a turbomachine engine 490. Compared to the device 300 of Figure 3, the device 400 further comprises first 410, second 420, third 430, fourth 460, fifth 470 regulation modules, first 440 and second 450 saturation modules, and transient intention detection modules 421 and 431, a sixth regulation module 480.

[0068] The sixth control module 480 is configured to determine a correction quantity dWFN2 of the fuel flow control WFC as a function of the minimum speed N2 min of the high-pressure body. This control makes it possible to control the engine 490 at idle. Instead of being carried out as a function of the minimum speed N2 min of the high-pressure body, the control can be carried out as a function of the minimum static pressure PS32 min in the combustion chamber or as a function of the minimum speed NI min of the low-pressure body.

[0069] Figure 5 schematically represents a method 500 for controlling a turbomachine implemented by the device of the invention, in particular by one of the devices of Figures 2, 3 and 4.

[0070] The method 500 comprises in step 510 a regulation for stationary speed, then in step 520 a detection of an intention of speed transient and in response to this detection 520, a step 530 of regulation of the speed transient. During step 510, the fuel flow control is determined as a function of a difference between a setpoint parameter which depends on the position of the engine control lever and an engine operating parameter. As indicated previously, the setpoint and operating parameter preferably correspond to the NI speed of the low pressure body or to the EPR engine pressure ratio. This step 510 can be implemented in particular by the first regulation module of the fuel control device according to any one of the embodiments previously described.

[0071] During step 520, a transient intention is detected when the difference between the set speed NIC of the low pressure body and the speed NI of the low pressure body is greater than a predetermined threshold S. More particularly, an acceleration is detected if the difference (NIC - NI) is greater than S, or a deceleration if the difference (NI - NIC) is greater than S. The predetermined threshold S is for example 200 revolutions per minute.

[0072] Then, in step 530, the fuel flow control is determined based on a difference between a low pressure body speed and a low pressure body speed setpoint varying over time and generated in a predetermined manner.

[0073] Steps 520 and 530 may be implemented by the second and third regulation modules of the fuel control device according to any of the previously described embodiments.

Claims

Claims

1. Device (200, 300, 400) for generating a fuel flow control (WFC) of a turbomachine (100) configured to propel an aircraft and comprising a low pressure body and a high pressure body, the device comprising: - a first stationary regime regulation module (210, 310, 410) configured to determine the fuel flow control (dWF) as a function of a difference between a setpoint parameter (NI setpoint) dependent on a position of a thrust control lever (212, 312, 412) and an operating parameter (NI) of the turbomachine representative of the thrust developed by the turbomachine; - a second low pressure spool speed transient regulation module (220, 320, 420) configured to determine the fuel flow control (dWFaccel) as a function of a difference between the low pressure spool speed (NI) and a low pressure spool speed setpoint varying over time according to a trajectory of the low pressure spool speed generated in a predetermined manner during acceleration of the turbomachine, in order to satisfy a need for evolution of the thrust during acceleration; and - a third regulation module (230, 330, 430) for the transient speed of the low pressure body configured to determine the fuel flow control (dWFdecel) as a function of a difference between the speed of the low pressure body (NI) and a speed setpoint of the low pressure body varying over time according to a trajectory of the low pressure speed generated in a predetermined manner during a deceleration of the turbomachine, in order to satisfy a need for evolution of the thrust during deceleration.

2. A device (300, 400) for generating a fuel flow command according to claim 1 also comprising: - a first fuel flow saturation module (340, 440) configured to determine a maximum fuel flow (WFmax) and so that the fuel flow control is less than the maximum fuel flow; - a second fuel flow saturation module (350, 450) configured to determine a minimum fuel flow (WFmin) and for the fuel flow command to be greater than a minimum fuel flow; and - a fourth regulation module (360, 460) configured to determine a correction quantity (WF dn / dt min) of the fuel flow control from a speed derivative setpoint (N2) of the high pressure body (dN2 / dt).

3. Device (300, 400) for generating a fuel flow command according to any one of claims 1 or 2, comprising a fifth regulation module (370, 470) for determining a correction quantity (dWF32decel) of the fuel flow command by integrating a setpoint of the derivative of the speed of the high pressure body (dN2 / dt decel) during a deceleration or an acceleration of the turbomachine.

4. Device (400) for generating a fuel flow command according to any one of claims 1 to 3, comprising a sixth regulation module (480) configured to determine a correction quantity (dWFN2) of the fuel flow command as a function of the minimum speed of the high pressure body.

5. Device for generating a fuel flow control according to any one of claims 1 to 4, in which the operating parameter and the associated setpoint parameter of the first regulation module is the speed of the low pressure body (NI).

6. A device for generating a fuel flow command according to any one of claims 1 to 4, wherein the operating parameter and the associated setpoint parameter of the first regulation module is an engine pressure ratio (EPR).

7. A method (500) of controlling a motor implemented by the generating device according to any one of claims 1 to 6, in which a fuel flow control is determined, the method comprising: - a regulation (510) for stationary regime in which the fuel flow control is determined as a function of a difference between a setpoint parameter dependent on a position of a control lever and an operating parameter of the engine; - a detection (520) of a regime transient intention (TopAccel, TopDecel); and - in response to the detection, a regulation (530) for speed transient in which the fuel flow control is determined as a function of a difference between a low pressure body speed and a predetermined generated time-varying low pressure body speed setpoint.

8. Turbomachine (100) comprising a device (200, 300, 400) for generating a fuel flow command according to any one of claims 1 to 6 configured to implement the method (500) according to claim 7.

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