A method and device for improving fan stability margin through speed reduction control

Abstract

The application belongs to the technical field of engine control, and particularly relates to a deceleration control method and device for improving fan stability margin. The method comprises the following steps: S1, obtaining an engine deceleration start time, a low-pressure conversion speed after deceleration and a nozzle throat area; S2, discretizing a low-pressure conversion speed change interval into a plurality of low-pressure conversion speed control amounts; S3, superimposing a nozzle throat area increase amount on the basis of an initial value of the nozzle throat area to form a first nozzle throat area, and simultaneously determining a second nozzle throat area for maintaining stable operation of the fan; S4, selecting a minimum value from the two nozzle throat areas and a maximum value of the nozzle throat area to form a nozzle throat area adjustment amount corresponding to the low-pressure conversion speed control amount; and S5, adjusting the nozzle throat area according to the corresponding relationship between the low-pressure conversion speed control amount and the nozzle throat area adjustment amount. The application can ensure that the deceleration time meets the index requirement and improve the aircraft maneuvering performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engine control, and particularly relates to a deceleration control method and device for improving fan stability margin. BACKGROUND

[0002] The latest generation of small-bypass-ratio turbofan engines usually adopt rear-view full-shield afterburner and two-dimensional nozzle and the like engine rear components to reduce infrared radiation characteristic signals. After the rear-view full-shield afterburner and two-dimensional nozzle are installed, the main engine outer and inner bypass pressure ratio needs to be improved to ensure that the cooling gas pressure of the afterburner and two-dimensional nozzle components is greater than the main flow passage pressure, so that effective cooling is achieved.

[0003] At present, the method of reducing the outer bypass area of the turbofan engine is usually adopted to improve the main engine outer and inner bypass pressure ratio. Although this method can effectively improve the main engine outer and inner bypass pressure ratio, the reduction of the outer bypass area also increases the fan working line and reduces the fan stability margin of the engine.

[0004] During the deceleration of the engine, the fan working line is above the steady-state working line, and the stability margin is further reduced. In the region of the high-altitude left boundary with small fan stability margin, the engine is prone to fan surge during deceleration. At present, the method of increasing the deceleration fuel supply and deceleration time is usually adopted to ensure the stable operation of the engine, and the disadvantages are as follows:

[0005] The control law of the whole engine is not optimized during the deceleration of the engine, and the working potential of the whole engine is not fully utilized. With the increase of the deceleration time, the aircraft maneuverability is reduced, which affects the in-flight working ability of the aircraft and the realization of the technical index, and has an adverse effect on the completion of the flight mission of the aircraft. SUMMARY

[0006] In order to solve the above problems, the application provides a deceleration control method and device for improving fan stability margin, which adjusts the deceleration working process of the whole engine by enlarging the nozzle throat area, and further reduces the deceleration time of the engine and improves the maneuverability of the aircraft.

[0007] The first aspect of the application provides a deceleration control method for improving fan stability margin, mainly comprising:

[0008] Step S1, obtaining the low-pressure conversion speed initial value and the nozzle throat area initial value at the deceleration start time of the engine, and the low-pressure conversion speed target value and the maximum nozzle throat area after the deceleration is completed;

[0009] Step S2, discretizing the speed interval from the low-pressure conversion speed initial value to the low-pressure conversion speed target value during the deceleration of the engine to form a plurality of low-pressure conversion speed control quantities;

[0010] Step S3, for each low-pressure conversion speed control quantity, determine, on the basis of the selected low-pressure conversion speed control quantity, the nozzle throat area increase amount when the low-pressure conversion speed is superimposed to the low-pressure conversion speed initial value, superimpose the nozzle throat area increase amount on the basis of the nozzle throat area initial value to form a first candidate value, and determine the nozzle throat area when the fan is kept stable under the selected low-pressure conversion speed control quantity as a second candidate value;

[0011] Step S4, select the minimum value among the first candidate value, the second candidate value and the nozzle throat area maximum value to form the nozzle throat area adjustment amount corresponding to the selected low-pressure conversion speed control quantity;

[0012] Step S5, when the engine enters the deceleration process, adjust the nozzle throat area according to the real-time low-pressure conversion speed and the corresponding relationship between the low-pressure conversion speed control quantity and the nozzle throat area adjustment amount.

[0013] Preferably, in step S2, the speed interval is discretized by taking 0.5% as the step size.

[0014] Preferably, in step S3, determining the nozzle throat area when the fan is kept stable under the selected low-pressure conversion speed control quantity comprises:

[0015] Step S31, according to the fan component characteristics, determine the fan stable working line corresponding to the lowest fan pressure ratio, obtain the first functional relationship between the fan conversion flow and the low-pressure conversion speed, and the second functional relationship between the fan pressure ratio and the low-pressure conversion speed;

[0016] Step S32, according to the first functional relationship and the second functional relationship, determine the fan conversion flow and the fan pressure ratio corresponding to the selected low-pressure conversion speed control quantity;

[0017] Step S33, according to the fan conversion flow and the fan pressure ratio, determine the nozzle throat area.

[0018] Preferably, in step S5, the nozzle throat area adjustment amount corresponding to the real-time low-pressure conversion speed is determined by interpolation.

[0019] The second aspect of the present application provides a deceleration control device for improving fan stability margin, mainly comprising:

[0020] A deceleration parameter acquisition module is configured to acquire the low-pressure conversion speed initial value and the nozzle throat area initial value at the engine deceleration start time, the low-pressure conversion speed target value and the nozzle throat area maximum value after the deceleration ends.

[0021] The low-pressure conversion speed discrete module is configured to discretize a speed interval from a low-pressure conversion speed initial value to a low-pressure conversion speed target value during engine deceleration, and form a plurality of low-pressure conversion speed control amounts.

[0022] The nozzle throat area calculation module is configured to determine, for each low-pressure conversion speed control amount, a nozzle throat area increase amount when the speed exceeds the low-pressure conversion speed initial value based on the selected low-pressure conversion speed control amount, and form a first candidate value by superimposing the nozzle throat area increase amount on the nozzle throat area initial value, and determine a nozzle throat area when the fan works stably under the selected low-pressure conversion speed control amount as a second candidate value.

[0023] The nozzle throat area selection module is configured to select a nozzle throat area adjustment amount corresponding to the selected low-pressure conversion speed control amount from the first candidate value, the second candidate value, and the nozzle throat area maximum value.

[0024] The nozzle throat adjustment module is configured to adjust the nozzle throat area according to the corresponding relationship between the low-pressure conversion speed control amount and the nozzle throat area adjustment amount based on the real-time low-pressure conversion speed when the engine enters the deceleration process.

[0025] Preferably, the low-pressure conversion speed discrete module is configured to discretize the speed interval by 0.5% as a step.

[0026] Preferably, the nozzle throat area calculation module includes:

[0027] The fan pressure ratio minimum working line calculation unit is configured to determine a fan pressure ratio minimum working line corresponding to the fan stable working according to the fan component characteristics, obtain a first function relationship between the fan conversion flow and the low-pressure conversion speed, and a second function relationship between the fan pressure ratio and the low-pressure conversion speed.

[0028] The fan conversion flow and fan pressure ratio calculation unit is configured to determine the fan conversion flow and the fan pressure ratio corresponding to the selected low-pressure conversion speed control amount according to the first function relationship and the second function relationship.

[0029] The nozzle throat area calculation unit is configured to determine the nozzle throat area according to the fan conversion flow and the fan pressure ratio.

[0030] Preferably, the nozzle throat adjustment module includes an interpolation unit configured to determine the nozzle throat area adjustment amount corresponding to the real-time low-pressure conversion speed by interpolation.

[0031] The application can ensure that the deceleration time meets the index requirements and improve the aircraft maneuverability. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Flow chart of a preferred embodiment of the method for improving fan stability margin of the application.

[0033] Figure 2 Schematic diagram of fan working line after optimization of nozzle throat area.

[0034] Figure 3 Schematic diagram of adjustment plan after optimization of matching between nozzle throat area and low-pressure converted speed during deceleration process. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be described in more detail below with reference to the drawings in the embodiments of the application. Identical or similar labels in the drawings represent identical or similar elements or elements with identical or similar functions. The described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. The embodiments described below with reference to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation on the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application. The embodiments of the application will be described in detail below with reference to the drawings.

[0036] The application provides a method and device for improving fan stability margin of deceleration control. During the deceleration process, the nozzle throat area is appropriately enlarged to realize the optimized matching of the whole machine during the deceleration process. According to the working characteristics of the turbofan engine, when the engine nozzle throat area is enlarged, the fan working line is lowered, but the sudden enlargement of the nozzle throat area will cause the sharp increase of the low-pressure turbine expansion ratio and the sharp increase of the low-pressure turbine power, which will cause the fan to over-speed. Therefore, the nozzle throat area adjustment plan can be set in a way that the nozzle throat area is gradually enlarged to match the decrease of the low-pressure converted speed, so as to realize the optimized matching of the whole machine during the deceleration process.

[0037] The first aspect of the application provides a method for improving fan stability margin of deceleration control, as shown in Figure 1 , mainly comprising:

[0038] Step S1, obtaining the initial value n 1r,max of the low-pressure converted speed at the engine deceleration start time and the initial value A 8,min of the nozzle throat area, the target value n 1r,min of the low-pressure converted speed after deceleration and the maximum value A 8,max of the nozzle throat area.

[0039] Step S2: Discretize the speed range from the initial value of the low-pressure converted speed to the target value of the low-pressure converted speed during the engine deceleration process to form multiple low-pressure converted speed control quantities.

[0040] In some alternative implementations, the speed range is discretized with a step size of 0.5%. For example, c) with a step size of 0.5%, in n... 1r,max and n 1r,min Select N points from the given data, denoted as n. 1r,1 n 1r,2 ...n 1r,N .

[0041] Step S3: For each low-pressure converted speed control value, determine the amount of nozzle throat area amplification when overshooting the initial value of the low-pressure converted speed based on the selected low-pressure converted speed control value. Add the amount of nozzle throat area amplification to the initial value of the nozzle throat area to form a first candidate value. At the same time, determine the nozzle throat area when the fan is kept working stably under the selected low-pressure converted speed control value as a second candidate value.

[0042] In this step, the first candidate value is denoted as A. 8,min +△A8(n 1r,N ), where △A8(n 1r,N ) represents the selected low-pressure equivalent speed control quantity n 1r,N Initial speed n for conversion from overspeed to low pressure 1r,max The increase in nozzle throat area can be obtained through a whole-machine performance calculation program.

[0043] For the second candidate value, in some optional implementations, the calculation process mainly includes:

[0044] Step S31: Determine the minimum operating line of the fan pressure ratio when the fan is operating stably based on the characteristics of the fan components, and obtain the converted flow rate w of the fan. a1r The first functional relationship w between the low-pressure converted speed and the speed. a1r =f(n) 1r ), and fan pressure ratio p if The second functional relationship p between the low-pressure converted speed and the speed. if =f(n) 1r ).

[0045] like Figure 2As shown, the horizontal axis represents the fan's converted flow rate, and the vertical axis represents the fan pressure ratio. The bottom solid line in the figure represents the fan's minimum operating line, and the top solid line represents the surge boundary. A steady-state operating line for the fan that takes into account the interests of all parties is selected between these two solid lines. When the engine decelerates, the original control system provides the control law shown by the upper dashed line in the figure. It can be seen from the figure that the fan approaches the surge boundary. To prevent it from exceeding the surge boundary, the deceleration time is usually lengthened. After optimization, the fan deceleration operating line is the lower dashed line, which shows that it is within the safe range. The fan has a high margin of safety, which can achieve rapid deceleration while ensuring flight safety.

[0046] Step S32: Determine the fan equivalent flow rate and fan pressure ratio corresponding to the selected low-pressure equivalent speed control quantity based on the first functional relationship and the second functional relationship;

[0047] Step S33: Determine the nozzle throat area, i.e., the second candidate value A, based on the fan's converted flow rate and fan pressure ratio. 8,NF .

[0048] Step S4: Select the lowest value from the first candidate value, the second candidate value and the maximum value of the nozzle throat area to form a nozzle throat area adjustment amount corresponding to the selected low-pressure converted speed control amount.

[0049] In this step, the final determined nozzle throat area adjustment amount A 8,N for:

[0050] A 8,N =min{A 8,min +△A8(n 1r,N ), A 8,max A 8,NF}

[0051] Step S5: When the engine enters the deceleration process, adjust the nozzle throat area according to the real-time low-pressure converted speed and the correspondence between the low-pressure converted speed control amount and the nozzle throat area adjustment amount.

[0052] In some alternative implementations, in step S5, the nozzle throat area adjustment amount corresponding to the real-time low-pressure converted speed is determined by interpolation.

[0053] like Figure 3 As shown, in the optimized nozzle throat area adjustment plan, the nozzle throat area increases as soon as the engine's low-pressure equivalent speed begins to decrease. Compared to the original nozzle throat area adjustment plan, this reduces deceleration time, thereby improving aircraft maneuverability and ensuring the successful completion of flight missions.

[0054] The second aspect of this application provides a speed reduction control device for improving fan stability margin, corresponding to the above-described method, mainly comprising:

[0055] a deceleration parameter acquisition module configured to acquire an initial value of a low-pressure conversion speed at a start time of engine deceleration and an initial value of a nozzle throat area, a target value of the low-pressure conversion speed after deceleration, and a maximum value of the nozzle throat area;

[0056] a low-pressure conversion speed discretization module configured to discretize a speed interval in which the low-pressure conversion speed decreases from the initial value of the low-pressure conversion speed to the target value of the low-pressure conversion speed during engine deceleration, to form a plurality of low-pressure conversion speed control amounts;

[0057] a nozzle throat area calculation module configured to determine, for each low-pressure conversion speed control amount, a nozzle throat area increase amount when the low-pressure conversion speed control amount is selected and the low-pressure conversion speed increases to the initial value of the low-pressure conversion speed, and to form a first candidate value by adding the nozzle throat area increase amount to the initial value of the nozzle throat area, and to determine a nozzle throat area when the low-pressure conversion speed control amount is selected and the fan works stably as a second candidate value;

[0058] a nozzle throat area selection module configured to select, from among the first candidate value, the second candidate value, and the maximum value of the nozzle throat area, a nozzle throat area adjustment amount corresponding to the selected low-pressure conversion speed control amount;

[0059] a nozzle throat adjustment module configured to adjust the nozzle throat area according to a corresponding relationship between the low-pressure conversion speed control amount and the nozzle throat area adjustment amount based on a real-time low-pressure conversion speed when the engine enters the deceleration process.

[0060] In some optional embodiments, the low-pressure conversion speed discretization module discretizes the speed interval by taking 0.5% as a step size.

[0061] In some optional embodiments, the nozzle throat area calculation module includes:

[0062] a fan pressure ratio minimum working line calculation unit configured to determine a fan pressure ratio minimum working line corresponding to fan stable working according to fan component characteristics, to obtain a first functional relationship between a fan conversion flow and the low-pressure conversion speed, and a second functional relationship between a fan pressure ratio and the low-pressure conversion speed;

[0063] a fan conversion flow and fan pressure ratio calculation unit configured to determine a fan conversion flow and a fan pressure ratio corresponding to the selected low-pressure conversion speed control amount according to the first functional relationship and the second functional relationship;

[0064] a nozzle throat area calculation unit configured to determine the nozzle throat area according to the fan conversion flow and the fan pressure ratio.

[0065] In some optional embodiments, the nozzle throat adjusting module comprises an interpolation unit configured to determine the nozzle throat area adjusting amount corresponding to the real-time low-pressure conversion speed by interpolation.

[0066] The application can ensure that the deceleration time reaches the index requirement and improve the aircraft maneuverability.

[0067] Although the application has been described in detail with general description and specific embodiments, some modifications or improvements can be made on the basis of the application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the application, all belong to the scope of the application claimed.

Claims

1. A method of improving fan stability margin for speed reduction control, characterized by, The method comprises the following steps: Step S1, obtaining the low-pressure conversion speed initial value and the nozzle throat area initial value at the engine deceleration start time, the low-pressure conversion speed target value after the deceleration ends, and the maximum nozzle throat area; Step S2, discretizing the speed interval from the low-pressure conversion speed initial value to the low-pressure conversion speed target value in the engine deceleration process to form a plurality of low-pressure conversion speed control amounts; Step S3, for each low-pressure conversion speed control amount, determining the nozzle throat area release amount when the selected low-pressure conversion speed control amount is super-transited to the low-pressure conversion speed initial value, and determining the nozzle throat area when the fan is stably operated under the selected low-pressure conversion speed control amount as a second candidate value; Step S4, selecting the minimum value from the first candidate value, the second candidate value, and the maximum nozzle throat area to form the nozzle throat area adjustment amount corresponding to the selected low-pressure conversion speed control amount; Step S5, when the engine enters the deceleration process, adjusting the nozzle throat area according to the corresponding relationship between the low-pressure conversion speed control amount and the nozzle throat area adjustment amount based on the real-time low-pressure conversion speed.

2. The method of claim 1, wherein the method is performed by a controller of the engine. In step S2, the speed interval is discretized by taking 0.5% as the step size.

3. The method of claim 1, wherein the method is performed by a controller of the engine. In step S3, determining the nozzle throat area when the fan is stably operated under the selected low-pressure conversion speed control amount comprises: Step S31, determining the fan stable operation corresponding fan pressure ratio minimum working line according to the fan component characteristics to obtain the first functional relationship between the fan conversion flow and the low-pressure conversion speed, and the second functional relationship between the fan pressure ratio and the low-pressure conversion speed; Step S32, determining the fan conversion flow and the fan pressure ratio corresponding to the selected low-pressure conversion speed control amount according to the first functional relationship and the second functional relationship; Step S33, determining the nozzle throat area according to the fan conversion flow and the fan pressure ratio.

4. The method of claim 1, wherein the method is performed by a controller of the engine. In step S5, the nozzle throat area adjustment amount corresponding to the real-time low-pressure conversion speed is determined by interpolation.

5. A deceleration control device for improving a fan stability margin, characterized by, The method comprises the following steps: A deceleration parameter acquisition module is configured to obtain the low-pressure conversion speed initial value and the nozzle throat area initial value at the engine deceleration start time, the low-pressure conversion speed target value after the deceleration ends, and the maximum nozzle throat area; A low-pressure conversion speed discretization module is configured to discretize the speed interval from the low-pressure conversion speed initial value to the low-pressure conversion speed target value in the engine deceleration process to form a plurality of low-pressure conversion speed control amounts; A nozzle throat area calculation module is configured to, for each low-pressure conversion speed control amount, determine the nozzle throat area release amount when the selected low-pressure conversion speed control amount is super-transited to the low-pressure conversion speed initial value, and determine the nozzle throat area when the fan is stably operated under the selected low-pressure conversion speed control amount as a second candidate value; The nozzle throat area selection module is configured to select a nozzle throat area from among the first candidate value, the second candidate value, and the maximum nozzle throat area, and to form a nozzle throat area adjustment value corresponding to the selected low-pressure conversion speed control value; The nozzle throat adjustment module is configured to, when the engine enters the deceleration process, adjust the nozzle throat area according to the real-time low-pressure conversion speed and the corresponding relationship between the low-pressure conversion speed control value and the nozzle throat area adjustment value.

6. The deceleration control device for improving a fan stability margin according to claim 5, wherein In the low-pressure conversion speed discretization module, the speed interval is discretized with a step of 0.5%.

7. The deceleration control device for improving a fan stability margin according to claim 5, wherein The nozzle throat area calculation module includes: The fan pressure ratio minimum working line calculation unit is configured to determine a fan pressure ratio minimum working line corresponding to a stable working state of the fan component according to a fan component characteristic, to obtain a first functional relationship between a fan conversion flow and the low-pressure conversion speed, and a second functional relationship between a fan pressure ratio and the low-pressure conversion speed; The fan conversion flow and fan pressure ratio calculation unit is configured to determine a fan conversion flow and a fan pressure ratio corresponding to the selected low-pressure conversion speed control value according to the first functional relationship and the second functional relationship; The nozzle throat area calculation unit is configured to determine the nozzle throat area according to the fan conversion flow and the fan pressure ratio.

8. The deceleration control device for improving a fan stability margin according to claim 5, wherein The nozzle throat adjustment module includes an interpolation unit configured to determine the nozzle throat area adjustment value corresponding to the real-time low-pressure conversion speed by interpolation.

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