A design method for control law of high-altitude low-speed thrust enhancement of aero-engines

Abstract

This application belongs to the field of aero-engine design and provides a design method for a thrust enhancement control law of aero-engines at medium and high altitudes with low indicated speeds. Based on user needs, the method defines the medium and high altitude regions with low indicated speeds requiring thrust enhancement. Then, it sets low-speed indicators for medium and high altitudes and high-speed indicators for high altitudes. Based on a stability reduction factor, it evaluates the engine's remaining stability margin under different Pit control laws. The first adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at medium and high speeds and the lower limit of the stability margin, and is converted into the angle adjustment amount of the expansion control plate corresponding to the medium and high altitude low speed region. The thrust enhancement value is calculated and evaluated until the target requirements are met. The control law is simple and can fully utilize the engine's comprehensive performance. It enables adaptive design control through engine control software, changing from a single control law to a two-dimensional control law, and allowing for regional adaptive adjustment design control laws.

Description

Technical Field

[0001] This application belongs to the field of aero-engine design, and specifically relates to a design method for the control law of improving thrust at low apparent speeds in aero-engines at medium and high altitudes. Background Technology

[0002] Aviation gas turbine fan engines are the core power plant for third, fourth, fifth and sixth generation aircraft both domestically and internationally. In order to meet the combat needs of aircraft in different flight envelopes and adapt to various complex and changing working environments, higher and more demanding requirements are constantly being put forward for the working capabilities of engines. For the mid-to-high altitude low speed flight area, which is reported both domestically and internationally as an area where dogfights frequently occur and are used, the demand for thrust is relatively strong.

[0003] To meet the requirements, a common approach is to continuously improve the temperature resistance of engine materials to achieve better performance, and also to improve the performance of various components. However, due to the limited pace of advancement in basic technologies, it is difficult to meet engine capability requirements in real time through these measures. Another approach is to optimize and match various systems under existing conditions and technologies, fully utilize the potential of each component and system, and further explore the engine's capabilities to meet the requirements. Currently, engine control laws are relatively simple. If the most conservative control law is adopted under constraints such as stability, lifespan, mechanical strength, and thermal intensity to ensure stable and safe engine operation, it will lead to the engine focusing more on safety factors, resulting in the overall performance not being fully utilized. The advantage is that the design and implementation of the control law are relatively simple.

[0004] For the engine in the intermediate and higher states, the control is based on the turbocharger pressure ratio Pit closed-loop control. The control law needs to remain monotonic and cannot be adaptively adjusted in different regions.

[0005] Therefore, how to improve the thrust of aero engines at low altitudes is a problem that needs to be solved. Summary of the Invention

[0006] The purpose of this application is to provide a design method for the control law of high-altitude low-speed thrust enhancement in aero-engines, so as to solve the problem in the prior art that it is difficult to simultaneously take into account the simplicity and stability of the control law and fully utilize the comprehensive performance of the engine.

[0007] The technical solution of this application is: a design method for control law of improving thrust at low apparent speeds in mid-to-high altitudes of aero-engines, including:

[0008] Based on user needs, the region with low apparent velocity at mid-to-high altitudes that requires thrust enhancement is defined.

[0009] Set separate low-speed indicators for mid-to-high altitudes and high-speed indicators for high altitudes. For the low-speed indicator for mid-to-high altitudes: set the initial value of the adaptive indicator to "0", and set it to "0" when T1≤A℃, B≤H≤C, and V b When the speed is less than D km / h, the initial value of the adaptive flag is "1", where the value of A ranges from 200 to 600, the values ​​of B and C range from 0 to 30, and the value of D ranges from 0 to 600. For high-altitude, high-speed flags, the initial value of the adaptive flag is set to "0", provided that T1 ≤ E℃, F ≤ H, and V b When the speed is ≥Gkm / h, the initial value of the adaptive flag is "2", where E ranges from 200 to 600, F ranges from 0 to 30, G ranges from 0 to 2000, and H is the flight altitude; V b T1 is the flight airspeed; T1 is the engine inlet temperature.

[0010] Within the thrust enhancement demand area, the engine's remaining stability margin under different Pit control laws is assessed based on the stability reduction factor to obtain the lower limit of the engine stability margin. The first adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at medium-high altitudes and low speeds and the lower limit of the stability margin, and then converted into the angle adjustment amount of the expansion control vane in the corresponding region of medium-high altitudes and low speeds. The thrust enhancement value is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met. Similarly, the second adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at high altitudes and high speeds and the lower limit of the stability margin, and then converted into the angle adjustment amount of the expansion control vane in the corresponding region of high altitudes and high speeds. The thrust enhancement value is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met.

[0011] Preferably, if the engine's remaining stability margin is less than the lower limit of the engine's stability margin, the adjustable blade angle a2 of the compressor is reduced. The amount of increase in the engine's remaining stability margin corresponding to each 1° reduction in the a2 angle is determined through compressor component testing, until the engine's remaining stability margin is greater than the lower limit of the engine's stability margin.

[0012] Preferably, the specific method for adjusting the angle of the expansion adjustment plate is as follows: first, determine the adjustment area of ​​the expansion adjustment plate corresponding to the nozzle required for the thrust adjustment at low speeds in mid-to-high altitudes; then, determine the number and position of each expansion adjustment plate in the area; and gradually increase the angle adjustment amount of the expansion adjustment plate from both ends to the middle of the area in a gradual manner until the thrust increase value requirement is met.

[0013] Preferably, when determining the angle adjustment amount of the expansion adjustment plate, first set the minimum angle adjustment unit amount, determine the thrust increase amount under the angle adjustment unit amount, then determine the angle adjustment amount required for each expansion adjustment plate to meet the target requirements, and adjust the angle of the expansion adjustment plate according to the angle adjustment amount.

[0014] Preferably, for areas outside of the adaptive initial values ​​of "1" and "2", the temperature resistance and mechanical strength of each engine component are determined and the difference between the temperature resistance and mechanical strength limit values ​​is input into the structural mechanics model to obtain the changes in temperature resistance and mechanical strength of each component when the thrust improvement target is required. Then, the engine thrust is improved by changing the temperature and mechanical load-bearing strength of the corresponding component area.

[0015] This application discloses a design method for a thrust enhancement control law of an aero-engine at low altitudes and mid-to-high altitudes. Based on user needs, the method defines the region at low altitudes and mid-to-high altitudes with thrust enhancement requirements. Then, it sets low-speed indicators for low altitudes and high-speed indicators for high altitudes. Within the region with thrust enhancement requirements, the remaining stability margin of the engine under different Pit control laws is evaluated based on a stability reduction factor to obtain the lower limit of the engine stability margin. The first adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at low speeds and mid-to-high altitudes and the lower limit of the stability margin. This adjustment is then converted into the angle adjustment amount of the expansion control vane corresponding to the low altitude and mid-to-high altitude region. The thrust enhancement value is calculated and evaluated to determine if the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met. The control law is simple and can fully utilize the engine's comprehensive performance. It enables adaptive design control in the engine control software, changing from a single control law to a two-dimensional control law, and adaptively adjusting the control law in different regions. While maintaining the thrust performance of other regions unchanged, it achieves thrust enhancement in the low altitude and mid-to-high altitude region. Attached Figure Description

[0016] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0017] Figure 1 This is a schematic diagram of the overall process of this application;

[0018] Figure 2 This is a schematic diagram defining the area of ​​the high-altitude low-speed indicator in this application;

[0019] Figure 3 This is a schematic diagram illustrating the optimization of the Pit control law in this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0021] A design method for high-altitude low-speed thrust enhancement control law of aero-engine is disclosed. The nozzle of the aero-engine must be a vector nozzle. The nozzle position of the vector nozzle is the expansion section of the vector nozzle. It has structures such as expansion adjustment vanes and heat shields. By changing the angle of the expansion adjustment vanes, the opening size of the vector nozzle can be adjusted, thereby increasing or decreasing the thrust of the aero-engine.

[0022] like Figure 1 As shown, it includes the following steps:

[0023] Step S100: Differentiate the thrust enhancement demand areas.

[0024] like Figure 2 As shown, based on user needs, the low-speed range at medium and high altitudes with thrust enhancement requirements is defined. There can be multiple defined ranges, and the areas outside the defined ranges are areas without thrust enhancement requirements.

[0025] The requirement refers to the issue of insufficient thrust at corresponding altitudes and speeds reported by users during actual flight, i.e., failure to meet the target requirements. This area is outlined for subsequent thrust-increasing design.

[0026] Step S200, Domain-based design and adaptive adjustment design

[0027] Separately set up low-speed indicators for mid-to-high altitudes and high-speed indicators for high altitudes:

[0028] For low-speed indicators at medium and high altitudes: Set the initial value of the adaptive indicator to "0", when T1≤A℃, B≤H≤C, and V b When the speed is less than D km / h, the initial value of the adaptive flag is "1", where the value of A ranges from 200 to 600, the values ​​of B and C range from 0 to 30, and the value of D ranges from 0 to 600.

[0029] For high-altitude, high-speed indicators, the adaptive indicator initial value is set to "0", provided that T1 ≤ E℃, F ≤ H, and V b When the speed is ≥Gkm / h, the initial value of the adaptive flag is "2", where E ranges from 200 to 600, F ranges from 0 to 30, G ranges from 0 to 2000, and H is the flight altitude; V b T1 is the flight airspeed; T2 is the engine inlet temperature.

[0030] By separately identifying the low-speed regions at mid-to-high altitudes and the high-speed regions at high altitudes, different methods can be used to process these different regions separately. Based on the above judgment criteria, once it is determined that the region corresponding to the low-speed regions at mid-to-high altitudes and the high-speed regions at high altitudes has been entered, the design for increasing thrust can begin until the required thrust is achieved.

[0031] Step S300: Design of thrust enhancement control law in the mid-to-high altitude low apparent velocity region

[0032] Within the thrust enhancement demand area, the engine's remaining stability margin is evaluated based on the stability reduction factor under different Pit control laws. The lower limit of the engine stability margin is obtained. The first adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at medium-high speed and low velocity and the lower limit of the stability margin. This is then converted into the angle adjustment amount of the expansion control vane in the corresponding region of medium-high altitude and low velocity. The thrust enhancement value is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met. Then, control is performed according to the optimized Pit law to achieve adaptive adjustment control law and enhance thrust in the medium-high altitude and low velocity region.

[0033] The second adjustment amount of the nozzle is determined based on the difference between the remaining stability margin and the lower limit of the stability margin at high altitude and high speed. This adjustment is then converted into the angle adjustment amount of the expansion control vane in the region corresponding to high altitude and high speed. The thrust increase is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met. Then, the control is performed according to the optimized Pit law to achieve adaptive adjustment control law and improve the thrust in the region of low apparent velocity at mid-to-high altitude.

[0034] Preferably, if the engine's remaining stability margin is less than the lower limit of the engine's stability margin, the adjustable blade angle a2 of the compressor is reduced. The amount of increase in the engine's remaining stability margin corresponding to each 1° reduction in the a2 angle is determined through compressor component testing, until the engine's remaining stability margin is greater than the lower limit of the engine's stability margin, so as to ensure the accuracy of thrust adjustment.

[0035] When adjusting the thrust of a conventional aero engine, the adjustment rules of each extended adjustment vane in the circumferential direction of the nozzle are consistent, that is, a single control law is used.

[0036] This application adopts a two-dimensional control law, that is, the control law of each expansion angle plate in the circumferential direction of the nozzle is not the same. By adaptively adjusting the design control law in a regional manner, while keeping the thrust performance of other regions unchanged, the thrust in the mid-to-high altitude low velocity region is improved.

[0037] Preferably, the specific method for adjusting the angle of the dilatation vanes is as follows: First, determine the adjustment area of ​​the dilatation vanes corresponding to the nozzle required for thrust adjustment at low speeds in mid-to-high altitudes. Then, determine the number and position of each dilatation vane in this area, and gradually increase the angle adjustment amount of the dilatation vanes from both ends of the area to the middle, until the thrust increase requirement is met. For example, if there are 10 dilatation vanes in the area, the angle adjustment of the dilatation vanes at both ends of the area is smaller, and the adjustment area of ​​the dilatation vanes becomes larger towards the middle of the area to ensure the stability of the adjustment.

[0038] Preferably, when determining the angle adjustment amount of the expansion control flaps, a minimum angle adjustment unit is first set, and the thrust increase under this unit is determined. Then, the required angle adjustment amount for each expansion control flap to meet the target is determined, and the expansion control flaps are adjusted according to this adjustment amount. That is, by first determining whether the expansion control flaps are adjusted (e.g., adjusting the edge expansion control flaps by 1°, the adjacent expansion control flaps by 1.5°, the middle expansion control flaps by 5°, while keeping the angles of the expansion control flaps in other areas unchanged), the increased thrust of the aero-engine is determined. If the target is still not met, each expansion control flap is then increased by 1° or 0.5° sequentially until the set target is met.

[0039] Preferably, for regions outside of the adaptive initial values ​​of "1" and "2", the temperature resistance and mechanical strength of each engine component are determined and input into the structural mechanics model, respectively, to obtain the changes in temperature resistance and mechanical strength of each component when the thrust enhancement target is required. Then, the engine thrust is increased by changing the temperature and mechanical load-bearing strength of the corresponding component regions. The final optimized Pit control law result is as follows: Figure 3 As shown, the upper left curve represents the Pit control law in the design state, the lower left curve represents the Pit control law in the optimization state, the area within the dashed box on the left represents the area with an initial adaptive value of "1", and the area within the dashed box on the right represents the area with an initial adaptive value of "2".

[0040] This application defines the mid-to-high altitude low-speed region with thrust enhancement requirements based on user needs. Then, it sets mid-to-high altitude low-speed and high-altitude high-speed indicators. Within the thrust enhancement region, it assesses the engine's remaining stability margin under different Pit control laws based on a stability reduction factor, obtains the lower limit of the engine stability margin, and determines the first adjustment amount of the nozzle based on the difference between the remaining stability margin at mid-to-high altitude low speeds and the lower limit of the stability margin. This is then converted into the angle adjustment amount of the expansion control vane corresponding to the mid-to-high altitude low-speed region. The thrust enhancement value is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met. The control law is simple and can fully utilize the engine's comprehensive performance. It enables adaptive design control of the engine's control software, changing from a single control law to a two-dimensional control law, and adaptively adjusting the control law in different regions. While maintaining the thrust performance of other regions unchanged, it achieves thrust enhancement in the mid-to-high altitude low-speed region.

[0041] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for designing control laws to enhance thrust at low apparent speeds in mid-to-high altitudes for aero-engines, characterized in that, include: Based on user needs, the region of low-speed readings at medium and high altitudes with thrust enhancement requirements is defined. Set separate low-speed indicators for mid-to-high altitudes and high-speed indicators for high altitudes. For the low-speed indicator for mid-to-high altitudes: set the initial value of the adaptive indicator to "0", and set it to "0" when T1≤A℃, B≤H≤C, and V b When the speed is less than D km / h, the initial value of the adaptive flag is "1", where the value of A ranges from 200 to 600, the values ​​of B and C range from 0 to 30, and the value of D ranges from 0 to 600. For high-altitude, high-speed flags, the initial value of the adaptive flag is set to "0", provided that T1 ≤ E℃, F ≤ H, and V b When the speed is ≥Gkm / h, the initial value of the adaptive flag is "2", where E ranges from 200 to 600, F ranges from 0 to 30, G ranges from 0 to 2000, and H is the flight altitude; V b T1 is the flight airspeed; T1 is the engine inlet temperature. Within the thrust enhancement demand area, the engine's remaining stability margin under different Pit control laws is assessed based on the stability reduction factor to obtain the lower limit of the engine stability margin. The first adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at medium-high altitudes and low speeds and the lower limit of the stability margin, and then converted into the angle adjustment amount of the expansion control vane in the corresponding region of medium-high altitudes and low speeds. The thrust enhancement value is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met. Similarly, the second adjustment amount of the nozzle is determined based on the difference between the remaining stability margin at high altitudes and high speeds and the lower limit of the stability margin, and then converted into the angle adjustment amount of the expansion control vane in the corresponding region of high altitudes and high speeds. The thrust enhancement value is calculated and evaluated to determine whether the target requirement is met. If not, the angle adjustment amount of the expansion control vane is increased until the target requirement is met.

2. The design method for high-altitude low-speed thrust enhancement control law of aero-engine as described in claim 1, characterized in that: If the engine's remaining stability margin is less than the lower limit of the engine's stability margin, then reduce the adjustable blade angle a2 of the compressor. Determine the increase in the engine's remaining stability margin corresponding to each 1° reduction in the a2 angle through compressor component testing, until the engine's remaining stability margin is greater than the lower limit of the engine's stability margin.

3. The design method for high-altitude low-speed thrust enhancement control law of aero-engine as described in claim 1, characterized in that, The specific method for adjusting the angle of the expansion adjustment plate is as follows: First, determine the adjustment area of ​​the expansion adjustment plate corresponding to the nozzle required for the thrust adjustment at low speeds in mid-to-high altitudes. Then, determine the number and position of each expansion adjustment plate in this area, and gradually increase the angle adjustment amount of the expansion adjustment plate from both ends to the middle of the area until the thrust increase value requirement is met.

4. The design method for high-altitude low-speed thrust enhancement control law of aero-engine as described in claim 3, characterized in that: When determining the angle adjustment amount of the expansion adjustment plate, first set the minimum angle adjustment unit, determine the thrust increase under this angle adjustment unit, then determine the angle adjustment amount required for each expansion adjustment plate to meet the target requirements, and adjust the angle of the expansion adjustment plate according to this angle adjustment amount.

5. The design method for high-altitude low-speed thrust enhancement control law of aero-engine as described in claim 1, characterized in that: For regions outside of the adaptive initial values ​​of "1" and "2", the temperature resistance and mechanical strength of each engine component are determined and input into the structural mechanics model, respectively, to obtain the changes in temperature resistance and mechanical strength of each component when the thrust improvement target is required. Then, the engine thrust is improved by changing the temperature and mechanical load-bearing strength of the corresponding component region.

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