A method for limiting acceleration of an aeroengine

Abstract

The application provides an aero-engine acceleration limiting method, and relates to the technical field of aero-engines, and comprises the following steps: receiving a flight control instruction, calculating a first fuel supply amount according to the flight control instruction, and executing single / dual-outer-envelop working mode conversion; detecting a position state of an actual mode selection valve and a rotating speed feedback value in real time; judging whether the current state of the engine meets the mode switching condition of single / dual-outer-envelop according to the position state of the mode selection valve; calculating a second fuel supply amount, a third fuel supply amount, and a fourth fuel supply amount according to the position state of the mode selection valve, combining the first fuel supply amount, a fifth fuel supply amount, taking the minimum value among the five fuel supply amounts, comparing the minimum value with a sixth fuel supply amount to take the maximum value, taking the minimum value with a seventh fuel supply amount, taking the maximum value of the comparison result with an eighth fuel supply amount as a control fuel supply amount output; and judging whether the engine is in an acceleration / deceleration state according to a rotating speed difference. The application solves the safety problem possibly caused by the acceleration / deceleration process of the dual-outer-envelop engine.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and more specifically to an aero-engine acceleration limitation method. Background Technology

[0002] Currently, twin-bypass aero-engines with CDFS (core engine driven fan stage) have two operating modes: single-bypass and twin-bypass. Single-bypass mode is the high-power operation mode, which provides consistently high thrust. Twin-bypass mode is the low-power operation mode, which offers better fuel economy and longer lifespan. To ensure flight safety and stability during the switching between these two operating modes, numerous restrictions are implemented, with acceleration limitation being one of the protective control methods.

[0003] The dual-bypass turbofan engine operating mode is not applicable to all flight envelopes. To ensure the engine operates at near-optimal conditions within the flight envelope, mode switching between dual-bypass and single-bypass turbofan modes is required, necessitating mode switching control. This mode switching control must satisfy two operating states: first, mode switching control must occur under steady-state conditions, which can be completed via pilot commands and offers high safety; second, mode switching control must occur during acceleration, which carries higher risks and may lead to engine intake distortion or surge, requiring appropriate control plans for protection.

[0004] Based on the changing characteristics of the dual-bypass engine mode switching parameters and safety requirements, the dual-bypass engine can operate in full operating conditions in single-bypass mode, while in dual-bypass mode it can only operate below the set speed. Therefore, when accelerating from dual-bypass mode to intermediate mode, mode switching is necessary. During acceleration, it is essential to implement protective control and design a reasonable limiting control plan. Summary of the Invention

[0005] In view of this, embodiments of this application provide an acceleration limitation method for an aero-engine to address potential safety issues arising during the acceleration process of a dual-bypass engine.

[0006] This application provides the following technical solution: a method for limiting the acceleration of an aircraft engine, comprising:

[0007] Step 1: Receive flight control commands, calculate the first fuel supply based on the flight control commands, and perform single / dual bypass working mode switching;

[0008] Step 2: Real-time detection of the actual position status and speed feedback value of the mode selection valve. The position status of the mode selection valve is either closed or not closed. The speed feedback value is the speed signal N2 detected by the speed sensor.

[0009] Step 3: Based on the position of the mode selection valve, determine whether the current state of the engine meets the conditions for switching between single and dual bypass modes. If the conditions are met, switch modes; otherwise, maintain the current state.

[0010] Step 4: Based on the position state of the mode selection valve, execute the set limit plan array corresponding to the position state of the mode selection valve on the relative physical speed relative to the engine inlet temperature T2 to obtain the maximum relative physical speed N2.max. Calculate the second fuel supply quantity based on the maximum relative physical speed N2.max.

[0011] Based on the position state of the mode selection valve, the exhaust temperature relative to the engine inlet temperature T2 is executed according to the set limit plan array corresponding to the position state of the mode selection valve to obtain the maximum exhaust temperature T5.max. Based on the maximum exhaust temperature T5.max, the third fuel supply quantity is calculated.

[0012] The fourth fuel supply quantity is calculated based on the compressor outlet pressure P3.max corresponding to the position state of the mode selection valve.

[0013] The fifth fuel supply quantity is calculated based on the set maximum fuel supply limit wf.max;

[0014] The first fuel supply quantity, the second fuel supply quantity, the third fuel supply quantity, the fourth fuel supply quantity, and the fifth fuel supply quantity are compared, and the minimum value of the comparison result is taken as the intermediate fuel supply quantity wfDem.zj1;

[0015] Step 5: Based on the engine dynamic model, formulate the deceleration limit plan wfDemDec=f5(N2,T2,P3) and the acceleration limit plan wfDemAcc=f4(N2,T2,P3), and obtain the airborne operating parameters in real time. Calculate the sixth and seventh fuel supply quantities in real time based on the airborne operating parameters.

[0016] Step 6: Calculate the difference between the given speed value N2Dem and the actual speed value N2, and compare the difference with the set slip threshold. If the difference is greater than the set slip threshold, it is determined to be an acceleration / deceleration state; if the difference is less than the set slip threshold, it is determined to be a steady state.

[0017] If the system is in an acceleration / deceleration state, the sixth fuel supply quantity is compared with the intermediate fuel supply quantity wfDem.zj1 in real time, and the maximum value of the comparison result is taken as the output fuel supply quantity wfDem.zj2; the output fuel supply quantity wfDem.zj2 is compared with the seventh fuel supply quantity, and the minimum value of the comparison result is taken as the output fuel supply quantity wfDem.zj3; the output fuel supply quantity wfDem.zj3 is compared with the eighth fuel supply quantity, and the maximum value of the comparison result is taken as the control fuel supply quantity wfDem.

[0018] According to one embodiment of this application, the airborne operating parameters include: high-pressure rotor speed N2, slip value, CDFS inlet total pressure P23, CDFS inlet static pressure Ps23, CDFS outlet total pressure P25, and mixing chamber static pressure Ps225 at the rear end of the mode selection valve.

[0019] According to one embodiment of this application, the first fuel supply quantity, the second fuel supply quantity, the third fuel supply quantity, and the fourth fuel supply quantity are calculated by the control system based on a classical control theory algorithm.

[0020] According to one embodiment of this application, in step 2, the position state of the mode selection valve is detected in real time by a displacement sensor.

[0021] According to one embodiment of this application, in step 3, the formula for determining the mode switching condition is: Mp = f1(N2, πcdfs, Ra, dN2 / dt);

[0022] Where Mp represents the class identifier of the mode switching condition, f1 represents the judgment function, N2 represents the relative converted speed of the high-pressure rotor, πcdfs represents the CDFS total pressure ratio, Ra represents the mode selection valve backflow margin, and dN2 / dt is the derivative of N2, representing the relative speed variable rate.

[0023] If dN2 / dt < a fixed value, and N2, πcdfs, and Ra respectively meet the set convertible threshold, then Mp is set to "1", indicating that the mode switching condition is met; if dN2 / dt ≮ a fixed value, then Mp is set to "0", indicating that the mode switching condition is not met.

[0024] According to one embodiment of this application, in step 4, the maximum relative physical speed N2.max executes a set limit plan array corresponding to the position state of the mode selection valve. The limit plan array is a segmented array, and the maximum relative physical speed N2.max is determined to execute the corresponding array according to the position state of the mode selection valve.

[0025] According to one embodiment of this application, in step 6, the difference is compared with a set slip threshold. If the difference is less than the set slip threshold, it is determined to be in a steady state.

[0026] If the condition is determined to be steady state, the output fuel supply will be executed according to the first fuel supply quantity, which is obtained by closed-loop calculation of throttle position and speed.

[0027] According to one embodiment of this application, in step 1, the flight control command includes a throttle lever command Pla and a mode switching command; the control system calculates the speed setpoint N2Dem based on the throttle lever command Pla, and calculates the first fuel supply amount based on the control algorithm.

[0028] Compared with the prior art, the beneficial effects that can be achieved by the above-mentioned at least one technical solution adopted in the embodiments of this specification include at least the following: the embodiments of this invention propose an acceleration limitation plan specifically for dual-bypass engines, clarify the method of using the dual-bypass engine acceleration limitation plan, predict the risks brought about by mode switching during acceleration for the dual-bypass engine acceleration process, and take protective measures to improve operational safety. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram illustrating the principle of the aero-engine acceleration limitation method according to an embodiment of the present invention. Detailed Implementation

[0031] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0032] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] like Figure 1 As shown, an embodiment of the present invention provides a method for limiting the acceleration of an aero-engine, including:

[0034] Step 1: Receive flight control commands, calculate the first fuel supply amount and execute the single / dual bypass working mode switch based on the flight control commands;

[0035] In step 1, the flight control commands include the throttle control command Pla and the mode switching command MB. The control system calculates the given speed N2Dem = f0(Pla) based on the throttle control command Pla, and calculates the first fuel supply amount based on the control algorithm.

[0036] The mode switching instruction MB indicates whether the dual-bypass aero-engine should be in single-bypass or dual-bypass operating mode according to the pilot's operating instructions.

[0037] Step 2: Real-time detection of the actual position status and speed feedback value of the mode selection valve. The position status of the mode selection valve is either closed or not closed, denoted by Msv; the speed feedback value is the speed signal N2 detected by the speed sensor.

[0038] The position status of the mode selection valve is detected and fed back in real time by a linear displacement sensor. When the displacement signal is 0, it means that the mode selection valve is fully closed, Msv = 0. When the displacement signal is not 0, it means that the mode selection valve is in the non-closed state, Msv = 1.

[0039] Step 3: Based on the position of the mode selection valve, determine whether the current state of the engine meets the conditions for switching between single and dual bypass modes. If the conditions are met, switch modes; otherwise, maintain the current state.

[0040] The formula for determining the mode switching condition is based on the current engine state parameters. The specific formula is: Mp = f1(N2, πcdfs, Ra, dN2 / dt); if Mp is "1", it means that the mode switching condition is met; if Mp is "0", it means that the mode switching condition is not met and the current state is maintained.

[0041] Where Mp is the class identifier for the mode switching condition, f1 represents the judgment function, N2 represents the relative converted speed of the high-pressure rotor, a convertible threshold is set, and the threshold condition is judged to be met; πcdfs represents the CDFS total pressure ratio (CDFS outlet total pressure P25 / CDFS inlet static pressure P23), a convertible threshold is set, and the threshold condition is judged to be met; Ra represents the mode selection valve backflow margin (Ps225-Ps23) / Ps23, a convertible threshold is set, and the threshold condition is judged to be met; dN2 / dt is the derivative of N2, representing the relative speed change rate; when dN2 / dt < a constant value, and N2, πcdfs, and Ra respectively meet the set convertible threshold, then Mp is set to "1", indicating that the mode switching condition is met; if dN2 / dt ≮ a constant value, regardless of whether N2, πcdfs, and Ra meet the set convertible threshold, Mp is set to "0", indicating that the mode switching condition is not met.

[0042] Preferably, if the pilot mode switching command MB and the mode switching condition Mp are both "1" (represented as MB&Mp=1), then the mode selection valve switching control is performed.

[0043] Step 4: Based on the position state of the mode selection valve, execute the set limit plan array corresponding to the position state of the mode selection valve on the relative physical speed relative to the engine inlet temperature T2 to obtain the maximum relative physical speed N2.max. Calculate the second fuel supply quantity based on the maximum relative physical speed N2.max.

[0044] The maximum relative physical speed N2.max is executed according to the set limit plan array corresponding to the position state of the mode selection valve, satisfying the maximum relative physical speed N2.max = f2(Msv, T2). The limit plan array is a two-part array, and the maximum relative physical speed N2.max is executed according to the position state of the mode selection valve.

[0045] Based on the position state of the mode selection valve, the maximum exhaust temperature relative to the engine inlet temperature T2 is executed according to the set limit plan array corresponding to the position state of the mode selection valve to obtain the maximum exhaust temperature T5.max. Based on the maximum exhaust temperature T5.max, the third fuel supply quantity is calculated.

[0046] The maximum exhaust temperature T5.max is executed according to the set limit plan array corresponding to the position state of the mode selection valve. The limit plan array adopts a two-part array, and the maximum exhaust temperature T5.max = f3(Msv, T2).

[0047] The fourth fuel supply quantity is calculated based on the compressor outlet pressure P3.max corresponding to the position state of the mode selection valve; wherein, the maximum limit value of the compressor outlet pressure P3.max is a constant.

[0048] The fifth fuel supply quantity is calculated based on the set maximum fuel supply limit wf.max;

[0049] The first fuel supply quantity, the second fuel supply quantity, the third fuel supply quantity, the fourth fuel supply quantity, and the fifth fuel supply quantity are compared, and the minimum value of the comparison result is taken as the intermediate fuel supply quantity wfDem.zj1;

[0050] Step 5: Based on the engine dynamic model, formulate the deceleration limit plan wfDemDec=f5(N2,T2,P3) and the acceleration limit plan wfDemAcc=f4(N2,T2,P3), and obtain the airborne operating parameters in real time. Based on the airborne operating parameters, calculate in real time to obtain the sixth fuel supply and the seventh fuel supply.

[0051] The airborne operating parameters include: the high-pressure speed relative to the CDFS inlet converted speed N2, the slip value, the CDFS inlet total pressure P23, the CDFS inlet static pressure Ps23, the CDFS outlet total pressure P25, and the static pressure Ps225 of the mixing chamber behind the mode selection valve.

[0052] In this embodiment, based on classical control theory algorithms, the first fuel supply quantity, the second fuel supply quantity, the third fuel supply quantity, and the fourth fuel supply quantity are calculated by the control system.

[0053] Step 6: Calculate the difference between the given speed value N2Dem and the actual speed value N2, and compare the difference with the set slip threshold. If the difference is greater than the set slip threshold, it is determined to be an acceleration / deceleration state; if the difference is less than the set slip threshold, it is determined to be a steady state.

[0054] If the system is in an acceleration / deceleration state, the sixth fuel supply quantity is compared with the intermediate fuel supply quantity wfDem.zj1 in real time, and the maximum value of the comparison result is taken as the output fuel supply quantity wfDem.zj2; the output fuel supply quantity wfDem.zj2 is compared with the seventh fuel supply quantity, and the minimum value of the comparison result is taken as the output fuel supply quantity wfDem.zj3; the output fuel supply quantity wfDem.zj3 is compared with the eighth fuel supply quantity, and the maximum value of the comparison result is taken as the control fuel supply quantity wfDem.

[0055] Optionally, if the determination is deceleration, the output fuel supply is executed according to the deceleration fuel supply wfDemDec=f5(N2,T2,P3), and the requirement to compare with the intermediate fuel supply wfDem.zj1 and take the larger value is met.

[0056] Optionally, if the determination is acceleration, the output fuel supply is executed according to the acceleration fuel supply wfDemAcc=f4(N2,T2,P3), and the requirement of taking the smaller value when compared with the intermediate fuel supply wfDem.zj2 is met.

[0057] Optionally, if the condition is determined to be steady state, the fuel supply is executed according to the first fuel supply quantity, which is calculated by closed-loop calculation of throttle position and speed.

[0058] Optionally, the fuel supply quantity should ultimately meet the requirement of not less than the eighth fuel supply quantity, which is determined by the minimum fuel supply quantity wf.min.

[0059] Where: MB is the pilot mode switching command; Mp is the class identifier of the mode switching condition; Msv is the mode selection valve feedback displacement; πcdfs is the CDFS total pressure ratio; Ra is the return margin; dN2 / dt is the relative speed variable rate, set value; Pla is the actual throttle lever angle; T2 is the engine inlet total temperature; T5 is the high-pressure turbine after-temperature measurement; P23 is the CDFS inlet total pressure; P25 is the CDFS outlet total pressure; Ps23 is the CDFS inlet static pressure; Ps225 is the mixing chamber static pressure at the rear end of the mode selection valve. P3 is the compressor outlet total pressure, N2 is the engine high-pressure speed relative to the physical speed, N2r is the high-pressure speed relative to the CDFS inlet converted speed, wfDem.max is the fuel supply limit under acceleration, which is the minimum fuel supply limit in the plan based on the engine's maximum permissible exhaust temperature T5.max, maximum permissible pressure P3.max, maximum fuel supply limit set at wf.max, and maximum relative physical speed N2.max, wfDemDec is the fuel supply under deceleration, and wf.min is the minimum fuel supply limit value.

[0060] This embodiment presents an acceleration limitation plan specifically for dual-bypass engines, which clarifies the method of using the dual-bypass engine acceleration limitation plan, anticipates the risks brought about by mode switching during acceleration, and takes protective measures to improve operational safety.

[0061] 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 limiting the acceleration of an aircraft engine, characterized in that, include: Step 1: Receive flight control commands, calculate the first fuel supply based on the flight control commands, and perform single / dual bypass working mode switching; Step 2: Real-time detection of the actual position status and speed feedback value of the mode selection valve. The position status of the mode selection valve is either closed or not closed. The speed feedback value is the speed signal N2 detected by the speed sensor. Step 3: Based on the position of the mode selection valve, determine whether the current state of the engine meets the conditions for switching between single and dual bypass modes. If the conditions are met, switch modes; otherwise, maintain the current state. Step 4: Based on the position state of the mode selection valve, execute the set limit plan array corresponding to the position state of the mode selection valve on the relative physical speed relative to the engine inlet temperature T2 to obtain the maximum relative physical speed N2.max. Calculate the second fuel supply quantity based on the maximum relative physical speed N2.max. Based on the position state of the mode selection valve, the exhaust temperature relative to the engine inlet temperature T2 is executed according to the set limit plan array corresponding to the position state of the mode selection valve to obtain the maximum exhaust temperature T5.max. Based on the maximum exhaust temperature T5.max, the third fuel supply quantity is calculated. The fourth fuel supply quantity is calculated based on the compressor outlet pressure P3.max corresponding to the position state of the mode selection valve. The fifth fuel supply quantity is calculated based on the set maximum fuel supply limit wf.max; The first fuel supply quantity, the second fuel supply quantity, the third fuel supply quantity, the fourth fuel supply quantity, and the fifth fuel supply quantity are compared, and the minimum value of the comparison result is taken as the intermediate fuel supply quantity wfDem.zj1; Step 5: Based on the engine dynamic model, formulate the deceleration limit plan wfDemDec=f5(N2,T2,P3) and the acceleration limit plan wfDemAcc=f4(N2,T2,P3), and obtain the airborne operating parameters in real time. Calculate the sixth and seventh fuel supply quantities in real time based on the airborne operating parameters. Step 6: Calculate the difference between the given speed value N2Dem and the actual speed value N2, and compare the difference with the set slip threshold. If the difference is greater than the set slip threshold, it is determined to be an acceleration / deceleration state; if the difference is less than the set slip threshold, it is determined to be a steady state. If the system is in an acceleration / deceleration state, the sixth fuel supply quantity is compared with the intermediate fuel supply quantity wfDem.zj1 in real time, and the maximum value of the comparison result is taken as the output fuel supply quantity wfDem.zj2; the output fuel supply quantity wfDem.zj2 is compared with the seventh fuel supply quantity, and the minimum value of the comparison result is taken as the output fuel supply quantity wfDem.zj3; the output fuel supply quantity wfDem.zj3 is compared with the eighth fuel supply quantity, and the maximum value of the comparison result is taken as the control fuel supply quantity wfDem.

2. The engine acceleration limiting method according to claim 1, characterized in that, The airborne operating parameters include: high-pressure rotor speed N2, slip value, CDFS inlet total pressure P23, CDFS inlet static pressure Ps23, CDFS outlet total pressure P25, and mixing chamber static pressure Ps225 at the rear end of the mode selection valve.

3. The method for limiting the acceleration of an aircraft engine according to claim 1, characterized in that, Based on classical control theory algorithms, the first fuel supply quantity, the second fuel supply quantity, the third fuel supply quantity, and the fourth fuel supply quantity are calculated by the control system.

4. The method for limiting the acceleration of an aero-engine according to claim 1, characterized in that, In step 2, the position status of the mode selection valve is detected in real time by a displacement sensor.

5. The method for limiting the acceleration of an aero-engine according to claim 1, characterized in that, In step 3, the formula for determining the mode switching condition is: Mp = f1(N2, πcdfs, Ra, dN2 / dt); Where Mp represents the class identifier of the mode switching condition, f1 represents the judgment function, N2 represents the relative converted speed of the high-pressure rotor, πcdfs represents the CDFS total pressure ratio, Ra represents the mode selection valve backflow margin, and dN2 / dt is the derivative of N2, representing the relative speed variable rate. If dN2 / dt < a fixed value, and N2, πcdfs, and Ra respectively meet the set convertible threshold, then Mp is set to "1", indicating that the mode switching condition is met; if dN2 / dt ≮ a fixed value, then Mp is set to "0", indicating that the mode switching condition is not met.

6. The method for limiting the acceleration of an aircraft engine according to claim 1, characterized in that, In step 4, the maximum relative physical speed N2.max executes the set limit plan array corresponding to the position state of the mode selection valve. This limit plan array is a segmented array, and the maximum relative physical speed N2.max is executed according to the position state of the mode selection valve.

7. The method for limiting the acceleration of an aircraft engine according to claim 1, characterized in that, In step 6, the difference is compared with a set slip threshold. If the difference is less than the set slip threshold, it is determined to be in a steady state. If the condition is determined to be steady state, the output fuel supply will be executed according to the first fuel supply quantity, which is obtained by closed-loop calculation of throttle position and speed.

8. The method for limiting the acceleration of an aircraft engine according to claim 7, characterized in that, In step 1, the flight control commands include throttle lever command Pla and mode switching command; the control system calculates the speed setpoint N2Dem based on the throttle lever command Pla, and calculates the first fuel supply amount based on the control algorithm.

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