CN113969842A - High-dynamic-response control method for thrust of aero-engine - Google Patents

High-dynamic-response control method for thrust of aero-engine Download PDF

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CN113969842A
CN113969842A CN202111235659.1A CN202111235659A CN113969842A CN 113969842 A CN113969842 A CN 113969842A CN 202111235659 A CN202111235659 A CN 202111235659A CN 113969842 A CN113969842 A CN 113969842A
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thrust
rotating speed
cmd
instruction
control
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CN113969842B (en
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李睿超
王向阳
王兵
张会强
谢峤峰
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Qinghang Aerospace Beijing Technology Co ltd
Tsinghua University
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Qinghang Aerospace Beijing Technology Co ltd
Tsinghua University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • F02C9/48—Control of fuel supply conjointly with another control of the plant

Abstract

The invention provides a thrust high-dynamic response control method for an aircraft engine, which has the core idea of avoiding the change of the rotating speed with slow dynamic response. The control system based on the method comprises two steps of control plan (realized by a thrust instruction setting module 1, a rotating speed instruction setting module 2 and a control input reference value setting module 3) and control algorithm (realized by a design controller 4) design: the module 1 generates a thrust instruction F according to the throttle lever angle and the air inlet conditioncmd(ii) a Module 2 according to FcmdGenerating a speed command Ncmd(ii) a Module 3 according to FcmdAnd NcmdGenerating fuel flow and geometrically variable component area/angle reference values; the controller 4 is a constant tracking feedback controller, and is designed to accelerate the response speed based on a pole allocation method and realize the non-static tracking of the instruction through a built-in integrator. The control method provided by the invention can enable the engine to have high dynamic response capability, and has potential application value in scenes such as stealth aircraft course control, carrier-based aircraft landing and the like.

Description

High-dynamic-response control method for thrust of aero-engine
Technical Field
The invention relates to a control method of an aircraft engine, and belongs to the technical field of control of aircraft engines.
Background
The aircraft engine provides thrust for the aircraft, and the aircraft has cruising and maneuvering capabilities. However, the thrust cannot be directly measured, and the conventional engine control system can only indirectly control the thrust by controlling measurable parameters such as rotating speed and the like. With the improvement of the performance of the aircraft, the indirect control method cannot meet the fine requirement of the aircraft on the thrust, and the direct control problem of the thrust needs to be solved urgently.
From the point of view of the functioning of the propulsion system, the study of the direct control of thrust can be divided into two phases, with a slight overlap: the first phase was about 1978-1995, where the emphasis was on optimizing the performance indicators (acceleration, range, etc.) of aircraft by improving the overall performance (thrust, fuel consumption) of the engine, a typical work being engine performance optimization control arising in the nineties of the last century; the second phase was 1990 to date, where the focus was on using engines to control aircraft attitude, and where the dynamic behaviour of engines and aircraft was of interest compared to the first phase. Typical application scenes comprise unsteady maneuvering of a fighter plane, takeoff and landing of a short-vertical-takeoff and landing aircraft, carrier-based aircraft landing, course control of a high-stealth aircraft and the like. In these application scenarios, the thrust is not only controlled to be "steady" and "quasi", but also has a sufficiently "fast" response speed.
At present, there are three main technical schemes for improving the response speed of the engine at home and abroad: 1) improving the bandwidth of the control system: the response speed is increased by increasing the bandwidth of the rotating speed control loop; 2) high-speed slow moving: the gas compressor is used for releasing gas to increase the rotating speed of the slow car, so that the acceleration time from the slow car to the maximum state is shortened; 3) relaxing the restriction requirements on the engine: in an emergency situation, the limits on compressor surge margin and turbine front temperature are relaxed, allowing the fuel flow to change at a faster rate. However, these methods have the following limitations: 1) mainly faces to civil aviation engines, and is not optimized aiming at the structure and the control characteristics of military aviation engines; 2) the starting point is still to improve the response speed of the rotor instead of directly controlling the thrust; 3) the method for high-speed slow vehicle and limitation relaxation is only suitable for a specific power state (such as slow vehicle) or a specific flight scene (such as takeoff), and cannot be used as a stock control method;
compared with the existing control method, the novel control method is provided aiming at the characteristic that the military aircraft engine is generally provided with the device with the adjustable throat area of the tail nozzle, the response speed of the thrust is effectively improved by the method of avoiding the fluctuation of the rotating speed, and the novel control method has good application value in aircraft attitude control scenes such as heading control of stealth aircraft, carrier landing of carrier-based aircraft and the like.
Disclosure of Invention
The invention aims to provide a thrust high-dynamic-response control method for an aeroengine. The method needs to complete control plan design and control algorithm design. The control plan specifies the state of the engine, which is realized by a thrust instruction setting module 1, a rotating speed instruction setting module 2 and a control input reference value setting module 3, and the control algorithm enables the engine to work in the specified state, which is realized by a controller 4.
Designing a control plan: the invention provides a novel control plan, which has the following specific functions: 1) the throttle lever angle is directly mapped to a thrust command: the method comprises the steps that the range of the required thrust of the aircraft is determined in advance according to flight conditions, and the angle change range of the throttle lever is linearly mapped between the minimum value and the maximum value of the required thrust; 2) determining a rotating speed instruction according to the thrust instruction, wherein the specific logic is as follows: when the thrust instruction changes, whether the current rotating speed meets the thrust requirement is judged through table lookup, if yes, the rotating speed instruction is frozen, the thrust of the engine is changed along an equal rotating speed line, the rotating speed instruction is regenerated after the thrust reaches a stable state, and the rotating speed of the engine is guided to be adjusted to a proper value along the equal thrust line. When the rotating speed can not meet the thrust requirement, the rotating speed instruction is generated again, and at the moment, the thrust and the rotating speed of the engine are changed simultaneously. 3) And the control input (including but not limited to fuel flow, throat area of a tail nozzle, guide vane angle, injection valve opening degree and the like) reference value of the engine is generated by looking up a table according to the thrust instruction and the rotating speed instruction.
Designing a control algorithm: the invention uses a constant tracking feedback controller to directly control the rotating speed and the thrust, and the controller 4 calculates a control signal according to a thrust instruction, a rotating speed instruction and a control input reference value to complete a control target.
Drawings
FIG. 1: the invention provides a schematic diagram of a thrust high dynamic response process.
FIG. 2: the invention provides a high-thrust dynamic response control system schematic block diagram.
FIG. 3: and a working logic diagram of the rotating speed setting module.
FIG. 4: available thrust range and thrust radius are illustrated.
FIG. 5: the corresponding relation between the rotating speed instruction and the thrust instruction is shown schematically.
FIG. 6: the invention is compared with the traditional scheme in the thrust response speed.
Detailed Description
The invention is further described with reference to the following figures and examples, which are included to provide a further understanding of the invention and are not to be construed as limiting the invention in any way.
Taking an engine as an example, an equal rotation speed line and an equal thrust line are taken, as shown in FIG. 1, and the control input in the figure is a fuel flow WFThroat area A of the rear nozzle8The rotation speed is a low-pressure rotor rotation speed line, and the principle of the control method is only illustrated here, and the type of the control input and the number of rotors are not particularly limited. Taking the initial thrust of 50% as an example, the acceleration process is kept unchanged compared with the traditional tail nozzle throat area (see A1->Path B1), the method provided by the invention enables the engine to be in the same initial thrust state along the path A2->B2->C2 path change, wherein A2->B2 is a constant speed thrust increasing process, B2->C2 is a constant thrust rev-up procedure. The function of each sub-module for implementing the control plan will be described below.
As shown in fig. 2, the control system based on this control method includes: the device comprises a thrust instruction setting module 1, a rotating speed instruction setting module 2, a control input reference value setting module 3 and a controller 4. The working logic or design method of each module is as follows:
1) the design method of the rotating speed instruction setting module 1 is as follows: the method comprises the steps that the range of the required thrust of the aircraft is determined in advance according to flight conditions, and the angle change range of the throttle lever is linearly mapped between the minimum value and the maximum value of the required thrust;
2) the operating logic of the rotational speed instruction setting module 2 is shown in fig. 3, and the implementation method of the decision logic or each flow of each step is as follows:
Figure BDA0003317592230000033
judging whether the rotating speed meets the thrust requirement: each actuating mechanism (including but not limited to fuel flow, throat area of a tail nozzle, guide vane angle, opening degree of an injection valve and the like) of the engine is changed in an actuating range, and a thrust change range corresponding to each rotating speed is recorded under the condition that engine parameters are not out of limits, and is called as an available thrust range, as shown in fig. 4. If the thrust instruction is in the available thrust range corresponding to the current rotating speed, the rotating speed meets the thrust requirement, otherwise, the rotating speed does not meet the thrust requirement;
Figure BDA0003317592230000034
judging whether the thrust reaches a steady state: when the relative error e between the thrust command and the actual thrust is less than epsilon, the duration is more than TεThe thrust is then considered to reach a steady state, where ε, TεIs a preset constant.
Figure BDA0003317592230000035
The method for generating the rotating speed instruction comprises the following steps: the minimum available thrust force F at a certain speed of rotation is obtained according to FIG. 4minAnd the maximum available thrust Fmax. Given thrust command FcmdDefining the thrust radius R at a certain rotational speed as:
R＝min(Fcmd–Fmin,Fmax–Fcmd)
the definition if and only if Fmin<Fcmd<FmaxIs present. The rotational speed at which the thrust radius is maximized is recorded as
Figure BDA0003317592230000031
Thrust command FcmdAnd
Figure BDA0003317592230000032
see fig. 5 for an example of the correspondence relationship of (a). FIG. 5 also shows the thrust-to-rotation speed correspondence relationship obtained by minimizing the throat area of the nozzle tip or minimizing the fuel consumption rate in the conventional control scheme, in which the rotation speed is recorded as
Figure BDA0003317592230000041
Generally, the conventional control plan has a smaller fuel consumption rate, and therefore, a weight coefficient α defined between 0 and 1 generates a rotation speed command as follows:
Figure BDA0003317592230000042
the rotating speed command generated by the method can balance the control effect between the thrust response speed and the economic index. Similarly, the control effect may be balanced between thrust response speed and other indicators such as turbine inlet temperature (turbine life).
3) The control input reference value setting module 3 generates the control input reference value by the following method: tabulating the corresponding relation between the control input and the thrust and the rotating speed in the figure 1, and obtaining a control input reference value by the module according to a table look-up of a thrust instruction and a rotating speed instruction;
4) the controller 4 is designed as follows: for a given steady state operating condition (F)cmd,Ncmd,Wf,ref,A8,ref,..), the engine linearization model is:
Figure BDA0003317592230000043
δy＝C·δx+D·δu
where δ represents the difference between the variable and its steady state value, the state quantity x is the rotor speed N, and x is N when there are multiple rotors1,N2,...]TControl quantity u ═ Wf,A8,...]TOutput y ═ F, N]TWhen there are multiple rotors, y is ═ F, N1,N2,...]T。
Definition error
Figure BDA0003317592230000044
And in conjunction with the engine linearization equation, the following augmented linearization equation can be obtained:
Figure BDA0003317592230000045
neglecting actuator dynamics, designing state feedback controller using pole allocation method for the augmentation system
Figure BDA0003317592230000046
And block-wise expand K and
Figure BDA0003317592230000047
the mathematical expression for the controller can be found as:
u＝Kx(x-xref)+Ke∫(y-ycmd)dt+uref
in the design process, the response speed of the controlled object is increased by a method of enabling the pole to be far away from the virtual axis, and finally the pole position is determined according to the speed limit of the executing mechanism.
The controller is designed by using the method, compared with the traditional control scheme of only adjusting fuel, the poles of the two schemes are arranged in the same area, the control effect comparison that the thrust is increased from 50% to 60% is given in figure 6, and the thrust change curve at the upper right corner shows that the fuel oil control method has obvious response speed advantage.

Claims (1)

1. The method is characterized in that the thrust of the aero-engine is adjusted based on the principle of avoiding the fluctuation of the rotating speed of a rotor, and a rotating speed instruction is determined by maximizing the thrust variation range under the constant rotating speed, so that the response speed and the thrust radius of the thrust are increased;
the control system based on the method is characterized by comprising a thrust instruction setting module 1, a rotating speed instruction setting module 2, a control input reference value setting module 3 and a controller 4 (shown in figure 1);
the thrust instruction setting module 1 determines the range of the required thrust of the aircraft according to the flight condition, and linearly maps the angle change range of the throttle lever between the minimum value and the maximum value of the required thrust;
the operating logic of the rotating speed instruction setting module 2 is shown in fig. 3, and the decision logic or the implementation method of each process in each step is as follows:
judging whether the rotating speed meets the thrust requirement: changing each actuating mechanism (including but not limited to fuel flow, throat area of a tail nozzle, guide vane angle, opening degree of an injection valve and the like) of the engine in an actuating range, recording thrust variation range corresponding to each rotating speed under the condition that engine parameters are not over-limited, and calling the thrust variation range as an available thrust range, as shown in fig. 4; if the thrust instruction is in the available thrust range corresponding to the current rotating speed, the rotating speed meets the thrust requirement, otherwise, the rotating speed does not meet the thrust requirement;
judging whether the thrust reaches a steady state: when the relative error e between the thrust command and the actual thrust is less than epsilon, the duration is more than TεThe thrust is then considered to reach a steady state, where ε, TεIs a preset constant;
the method for generating the rotating speed instruction comprises the following steps: the minimum available thrust force F at a certain speed of rotation is obtained according to FIG. 4minAnd the maximum available thrust FmaxGiven a thrust command FcmdDefining the thrust radius R at a certain speed as (the definition is if and only if F)min<Fcmd<FmaxWhen present):
R＝min(Fcmd–Fmin,Fmax–Fcmd)
make the thrust radius maximumAt a rotational speed of
Figure FDA0003317592220000011
Thrust command FcmdAnd
Figure FDA0003317592220000012
see fig. 5 for an example of the correspondence; FIG. 5 also shows the thrust-to-rotation speed correspondence relationship obtained by minimizing the throat area of the nozzle tip or minimizing the fuel consumption rate in the conventional control scheme, in which the rotation speed is recorded as
Figure FDA0003317592220000013
Generally, the conventional control plan has a smaller fuel consumption rate, and therefore, a weight coefficient α defined between 0 and 1 generates a rotation speed command as follows:
Figure FDA0003317592220000014
the rotating speed instruction generated by the method can balance the control effect between the thrust response speed and the economic index, and similarly can balance the control effect between the thrust response speed and other indexes such as turbine inlet temperature (turbine service life);
the control input reference value setting module 3 generates the control input reference value by the following method: tabulating the corresponding relation between the control input and the thrust and the rotating speed in the figure 1, and obtaining a control input reference value by the module according to a table look-up of a thrust instruction and a rotating speed instruction;
the controller 4 is a constant tracking multiple input-multiple output feedback controller, and the design method is as follows: for a given steady state operating condition (F)cmd,Ncmd,Wf,ref,A8,ref,..), the engine linearization model is:
Figure FDA0003317592220000021
δy＝C·δx+D·δu
where δ represents the difference between the variable and its steady state value, the state quantity x is the rotor speed N, and the control quantity u is [ W ═ Wf,A8,...]TOutput y ═ F, N]T(when there are multiple rotors, y ═ F, N1,N2,...]T) Definition error of
Figure FDA0003317592220000022
And in conjunction with the engine linearization equation, the following augmented linearization equation can be obtained:
Figure FDA0003317592220000023
neglecting actuator dynamics, designing state feedback controller using pole allocation method for the augmentation system
Figure FDA0003317592220000024
And block-wise expand K and
Figure FDA0003317592220000025
the mathematical expression for the controller can be found as:
u＝Kx(x-xref)+Ke∫(y-ycmd)dt+uref
during design, the dynamic performance of the controller is accelerated by arranging the pole at a position far away from the virtual axis, the pole position is determined according to the speed limit of the actuating mechanism, the controller simultaneously controls the rotating speed and the thrust, and the static error-free tracking of the rotating speed and the thrust instruction is realized through the built-in integrator.
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