A design method for the control law of aircraft engine speed rise rate

Abstract

The present application belongs to the field of engine control technology, and specifically relates to a method for designing a speed increase rate control law for an aircraft engine. The method comprises step S1, determining a speed increase rate relationship curve when controlling the engine according to the oil-gas ratio control law under standard atmospheric conditions, wherein the horizontal axis of the speed increase rate relationship curve is the speed under standard atmospheric conditions, and the vertical axis is the speed increase rate control plan value; step S2, correcting the speed increase rate control plan value based on the starting speed and target ending speed of the engine acceleration process to obtain a corrected speed increase rate control plan value; step S3, determining a speed increase rate set value based on the corrected speed increase rate control plan value. The present application can quickly and accurately design a speed increase rate control plan value, thereby ensuring both acceleration requirements and stable engine operation.

Description

Technical Field

[0001] The present application belongs to the field of engine control technology, and specifically relates to a design method for a control law of the speed increase rate of an aircraft engine. Background Art

[0002] Currently, aircraft engine acceleration is typically controlled using an accelerated fuel supply method based on the fuel-to-air ratio. The design of fuel-to-air ratio control plans is relatively mature and has been fully validated. However, with advancements in aircraft engine technology and the widespread adoption of the full authority digital electronic control (FADEC), the acceleration process is now adopting closed-loop speed rise rate control to further improve control accuracy and avoid control deviations caused by accessory fuel supply deviations.

[0003] Methods for controlling the speed increase rate during acceleration have yet to be widely adopted, and relatively few design methods exist for this purpose. Numerical simulation models are typically used for this design, but these methods are significantly impacted by model accuracy. Due to the large operating envelope and complex systems of aircraft engines, the accuracy of numerical simulation models is generally low, making rapid application of these methods difficult. Numerical simulation models require extensive testing and verification, which not only requires significant manpower and resources, but also makes it difficult to ensure timely engineering implementation. Summary of the Invention

[0004] In order to solve one of the above problems, the present application provides a design method for the control law of the speed increase rate of an aircraft engine. Through the test results under the existing acceleration process oil-gas ratio control, a speed increase rate control plan that can be applied to engineering practice is quickly obtained.

[0005] The design method of the aircraft engine speed rise rate control law provided in this application mainly includes:

[0006] Step S1: Determine the speed increase rate relationship curve when the engine is controlled according to the fuel-air ratio control law under standard atmospheric conditions. The horizontal axis of the speed increase rate relationship curve is the speed n under standard atmospheric conditions. c , the vertical axis is the speed increase rate control plan value f ndot (n c ) st , which is set to:

[0007]

[0008] Among them, ndot is the speed increase rate, P 31 is the compressor outlet pressure, T1 is the total temperature of the engine inlet;

[0009] Step S2, correcting the speed increase rate control plan value based on the starting speed and the target ending speed of the engine acceleration process to obtain a corrected speed increase rate control plan value;

[0010] Step S3: Determine a speed increase rate set value based on the corrected speed increase rate control plan value.

[0011] Preferably, step S1 further comprises:

[0012] Step S11: Obtain the speed n under multiple standard atmospheric conditions c And the corresponding speed increase rate control plan value f ndot (n c ) st ;

[0013] Step S12: Determine the speed increase rate relationship curve by drawing or fitting.

[0014] Preferably, step S2 further includes correcting the speed increase rate control plan value based on a surge margin.

[0015] Preferably, modifying the speed increase rate control plan value based on the surge margin includes:

[0016] Divide the engine speed into segments when entering acceleration;

[0017] Determine the surge margin for each speed segment;

[0018] For the corresponding segmented speeds whose surge margin is less than the set value, the speed increase rate control plan value corresponding to the segmented speed is reduced according to the set ratio. Similarly, for the corresponding segmented speeds whose surge margin is greater than the set value, the speed increase rate control plan value corresponding to the segmented speed is increased according to the set ratio.

[0019] Preferably, in step S2, the speed increase rate control plan value is modified based on the starting speed and the target ending speed of the engine acceleration process, including:

[0020] Step S21, determining a first difference between the converted speed at the start of this acceleration and the converted speed in the idling state, and determining a second difference between the target converted speed at the end of this acceleration and the maximum converted speed in the intermediate state;

[0021] Step S22: For any speed, in the speed increase rate relationship curve, shift it rightward by the first difference to form the right control value of the speed; and at the same time, shift it leftward by the second difference to form the left control value of the speed;

[0022] Step S23: For the speed, select the minimum value among the left control value, the right control value and the corresponding speed increase rate control plan value as the corrected speed increase rate control plan value.

[0023] Preferably, in step S3, the speed increase rate set value ndot is determined based on the modified speed increase rate control plan value m. Dem for:

[0024]

[0025] The key point of this application is how to accurately summarize the given value of the speed increase rate through the existing test data based on oil-gas ratio control, so as to ensure both acceleration and stable engine control.

[0026] This application can quickly and accurately design a speed increase rate control plan value based on the existing actual speed increase rate value under the fuel-gas ratio control method, which can be well applied in actual engineering (both ensuring acceleration requirements and stable engine operation). Compared with traditional simulation calculation methods, it not only saves a large amount of test verification time and resources, but also greatly shortens the engineering application cycle of the speed increase rate control plan value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a preferred embodiment of the design method of the aircraft engine speed increase rate control law of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0029] The design method of the control law of the aircraft engine speed increase rate provided in this application is as follows: Figure 1 As shown, it mainly includes:

[0030] Step S1: Determine the speed increase rate relationship curve when the engine is controlled according to the fuel-air ratio control law under standard atmospheric conditions. The horizontal axis of the speed increase rate relationship curve is the speed n under standard atmospheric conditions. c , the vertical axis is the speed increase rate control plan value f ndot (n c ) st , which is set to:

[0031]

[0032] Among them, ndot is the speed increase rate, P 31 is the compressor outlet pressure, and T1 is the total temperature at the engine inlet.

[0033] With the continued use of aircraft engines, a large amount of test and flight data has been accumulated, fully validating the acceleration control methods under traditional fuel-to-air ratio control methods. At the same time, a large number of actual speed increase rate laws have been obtained. To ensure that the designed speed increase rate control plan values ​​can be quickly applied in engineering practice, it is necessary to summarize the speed increase rate control law from the traditional fuel-to-air ratio control law.

[0034] 1) According to the engine principle, in the dynamic process, when the geometric angle law is given and the engine inlet conditions (total temperature T1 and total pressure P1) are constant:

[0035]

[0036] Where, is the speed increase rate, n c is the speed converted to standard atmospheric conditions; wf is the fuel flow entering the main combustion chamber.

[0037] 2) The traditional oil-gas ratio control law is:

[0038]

[0039] Where, f wf (n c ) st is the given value of the oil-gas ratio under standard atmospheric conditions; P 31 is the compressor outlet pressure;

[0040] 3) Combining formulas (1) and (2), we can get:

[0041]

[0042] 4) Arrange formula (3) and re-evaluate it as follows:

[0043]

[0044] Where, f ndot (n c ) st It is the given value of the speed increase rate under standard atmospheric conditions.

[0045] Therefore, in step S1, the current oil-gas ratio control Rule, that is, the horizontal axis is n c and the vertical axis is Generate a speed rise rate curve.

[0046] In some optional embodiments, step S1 further includes:

[0047] Step S11: Obtain the rotation speed n under multiple standard atmospheric conditions c And the corresponding speed increase rate control plan value f ndot (n c ) st ;

[0048] Step S12: Determine the speed increase rate relationship curve by drawing or fitting.

[0049] Step S2: correcting the speed increase rate control plan value based on the starting speed and the target ending speed of the engine acceleration process to obtain a corrected speed increase rate control plan value.

[0050] During the acceleration process, the starting speed of the engine and the target ending speed are different. In order to ensure that the engine can work stably (as long as the speed increase rate is less than the given value of f ndot (n c ) st Therefore, in some optional embodiments, in step S2, the speed increase rate control plan value is corrected based on the starting speed and the target ending speed of the engine acceleration process, including:

[0051] Step S21, determining a first difference between the converted speed at the start of this acceleration and the converted speed in the idling state, and determining a second difference between the target converted speed at the end of this acceleration and the maximum converted speed in the intermediate state;

[0052] Step S22: For any speed, in the speed increase rate relationship curve, shift it rightward by the first difference to form the right control value of the speed; and at the same time, shift it leftward by the second difference to form the left control value of the speed;

[0053] Step S23: For the speed, select the minimum value among the left control value, the right control value and the corresponding speed increase rate control plan value as the corrected speed increase rate control plan value.

[0054] Step S3: Determine a speed increase rate set value based on the revised speed increase rate control plan value.

[0055] In some optional embodiments, in step S3, the speed increase rate set value ndot is determined based on the modified speed increase rate control plan value m. Dem for:

[0056]

[0057] Combined with the description of modifying the speed increase rate control plan value in step S2, the calculation formula finally formed in step S3 is:

[0058]

[0059] Among them, f nd o t (n c ) st The starting point is n c_mcMin and the end point is n c_zjMax The speed rise rate control plan value under standard atmospheric conditions;

[0060] n c起始 and n c_mcMin The converted speed at the start of this acceleration and the converted speed value in the slow state;

[0061] n c终止 and n c_zjMax The target converted speed at the end of this acceleration and the maximum converted speed value in the intermediate state;

[0062] shift_R(f ndot (n c ) st ,n c起始 -n cmc ) is f ndot (n c ) st Press n c Shift right by n c起始 -n c_mcMin The value after

[0063] shift_L(f ndot (n c ) st ,n c终止 -n czj ) is f ndot (n c ) st Press n c Shift left by n c终止 -n c_zjMax The value after.

[0064] In some optional embodiments, step S2 further includes modifying the speed increase rate control plan value based on the surge margin. Based on the stability margin of the existing engine, the speed increase rate control plan is locally adjusted while ensuring that the acceleration meets the requirements. For example, if the surge margin of the aircraft engine is relatively small within a certain speed range, the speed increase rate in this speed range can be appropriately reduced, while simultaneously increasing the speed range with a relatively large surge margin to ensure that the acceleration meets the requirements. Specifically, in some optional embodiments, modifying the speed increase rate control plan value based on the surge margin includes:

[0065] Divide the engine speed into segments when entering acceleration;

[0066] Determine the surge margin for each speed segment;

[0067] For the corresponding segmented speeds whose surge margin is less than the set value, the speed increase rate control plan value corresponding to the segmented speed is reduced according to the set ratio. Similarly, for the corresponding segmented speeds whose surge margin is greater than the set value, the speed increase rate control plan value corresponding to the segmented speed is increased according to the set ratio.

[0068] It should also be noted that, based on the patterns in the fitted statistical graph, the speed increase rate setpoints can be appropriately divided into regions; for example, based on the engine acceleration requirements (generally given by altitude and indicated speed), different speed increase rate control plan values ​​can be given at different altitudes and indicated speeds.

[0069] This application can quickly and accurately design a speed increase rate control plan value based on the existing actual speed increase rate value under the fuel-gas ratio control method, which can be well applied in actual engineering (both ensuring acceleration requirements and stable engine operation). Compared with traditional simulation calculation methods, it not only saves a large amount of test verification time and resources, but also greatly shortens the engineering application cycle of the speed increase rate control plan value.

[0070] Although the present application has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present application. Therefore, such modifications or improvements, which do not depart from the spirit of the present application, are within the scope of protection claimed in the present application.

Claims

1. A method for designing a control law for the speed increase rate of an aircraft engine, characterized in that: include: Step S1: Determine the speed increase rate relationship curve when the engine is controlled according to the fuel-air ratio control law under standard atmospheric conditions. The horizontal axis of the speed increase rate relationship curve is the speed n under standard atmospheric conditions. c , the vertical axis is the speed increase rate control plan value f ndot (n c ) st , which is set to: Among them, ndot is the speed increase rate, P 31 is the compressor outlet pressure, T1 is the total temperature of the engine inlet; Step S2, correcting the speed increase rate control plan value based on the starting speed and the target ending speed of the engine acceleration process to obtain a corrected speed increase rate control plan value; Step S3: Determine a speed increase rate set value based on the corrected speed increase rate control plan value.

2. The method for designing a control law for the aircraft engine speed increase rate according to claim 1, wherein: Step S1 further comprises: Step S11: Obtain the rotation speed n under multiple standard atmospheric conditions c And the corresponding speed increase rate control plan value f ndot (n c ) st ; Step S12: Determine the speed increase rate relationship curve by drawing or fitting.

3. The method for designing a control law for the aircraft engine speed increase rate according to claim 2, wherein: Step S2 further includes correcting the speed increase rate control plan value based on the surge margin.

4. The method for designing a control law for the aircraft engine speed increase rate according to claim 3, wherein: Modifying the speed increase rate control plan value based on the surge margin includes: Divide the engine speed into segments when entering acceleration; Determine the surge margin for each speed segment; For the corresponding segmented speeds whose surge margin is less than the set value, the speed increase rate control plan value corresponding to the segmented speed is reduced according to the set ratio. Similarly, for the corresponding segmented speeds whose surge margin is greater than the set value, the speed increase rate control plan value corresponding to the segmented speed is increased according to the set ratio.

5. The method for designing a control law for the aircraft engine speed increase rate according to claim 1, wherein: In step S2, the speed increase rate control plan value is modified based on the starting speed and the target ending speed of the engine acceleration process, including: Step S21, determining a first difference between the converted speed at the start of this acceleration and the converted speed in the idling state, and determining a second difference between the target converted speed at the end of this acceleration and the maximum converted speed in the intermediate state; Step S22: For any speed, in the speed increase rate relationship curve, shift it rightward by the first difference to form the right control value of the speed; and at the same time, shift it leftward by the second difference to form the left control value of the speed; Step S23: For the speed, select the minimum value among the left control value, the right control value and the corresponding speed increase rate control plan value as the corrected speed increase rate control plan value.

6. The method for designing a control law for the aircraft engine speed increase rate according to claim 1, wherein: In step S3, the speed increase rate set value ndot is determined based on the modified speed increase rate control plan value m. Dem for:

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