Variable geometry component characteristic modeling method for variable cycle engine based on reference characteristic line

Abstract

The application discloses a variable cycle engine variable geometry component characteristic modeling method based on a benchmark characteristic line, and comprises the following steps: a component working point offset coefficient model of a negative opening guide vane angle of a variable cycle engine is established; a negative opening guide vane angle component characteristic diagram is generated; a positive opening guide vane angle component characteristic diagram is expanded and corrected according to engineering experience; and simulation verification is carried out based on the positive and negative opening guide vane angle component characteristic diagrams. The application adopts a neural network to learn a variable cycle engine variable geometry component working point offset rule of a mature design, generates a negative opening guide vane angle component characteristic diagram based on a neural network offset coefficient model, further expands and corrects a positive opening guide vane angle component characteristic diagram based on least squares and engineering experience, and improves the integrity and accuracy of a variable cycle engine component level model. The method can quickly establish positive and negative opening guide vane angle component characteristics of a to-be-designed variable cycle engine based on a benchmark characteristic line by migrating a mature variable geometry component characteristic rule, and is suitable for various variable geometry rotating components.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine modeling technology, specifically relating to a method for modeling the characteristics of variable geometry components in a variable-cycle engine based on a baseline characteristic line. Background Technology

[0002] Faced with increasingly higher flight altitudes, Mach numbers, and more complex flight missions, traditional aero engines such as turbofan or turbojet engines are struggling to meet the performance demands of aircraft. Variable cycle engines, by adjusting the geometry of their components to switch between single / twin bypass operating modes, achieve the advantage of high thrust-to-weight ratio and low cruise fuel consumption. Furthermore, variable geometry adjustment can improve the stability margins of components such as the compressor without significantly reducing thrust, thereby enhancing engine operational safety. In addition, variable cycle engines can achieve supersonic cruise without afterburner, improving the economic efficiency of supersonic cruise for fighter jets. Therefore, variable cycle engines, with their inherent performance advantages and enormous development potential, have attracted the attention and research of developed aviation nations.

[0003] Mathematical models of variable cycle engines are fundamental to engine control system design. Internationally, research on the overall structural design and numerical simulation of variable cycle engines began as early as the 1960s; however, related literature lacked knowledge on modeling key geometric components. While domestically, variable cycle engine models have been established and their dynamic and steady-state simulation capabilities verified, issues such as incomplete geometric component variation characteristics leading to model non-convergence persist. A variable cycle engine variable geometry component characteristic modeling method based on a baseline characteristic line can rapidly establish the characteristics of the positive and negative opening guide vane angle components to be designed by transferring mature variable geometry component characteristic laws based on the baseline characteristic line, thereby improving the completeness, stability, and accuracy of the variable cycle engine component-level model. Summary of the Invention

[0004] Objective: To improve the characteristics of variable geometry components and enhance the stability of the model operation when the guide vane angle of a variable cycle engine changes, this invention proposes a modeling method for the characteristics of variable geometry components of a variable cycle engine based on a baseline characteristic line. Based on neural networks and least squares, supplemented by mature variable geometry component characteristic laws transferred from engineering experience, the method rapidly establishes the characteristics of the positive and negative opening guide vane angle components to be designed using the baseline characteristic line. This improves the operational stability, completeness, and reliability of the variable cycle engine component-level model when the guide vane angle of the variable geometry component changes.

[0005] To achieve the above objectives, a method for modeling the characteristics of variable geometry components in a variable cycle engine based on a baseline characteristic line is provided, comprising the following steps:

[0006] Step 1: Establish a component operating point offset coefficient model for the negative opening guide vane angle of a variable cycle engine;

[0007] Step 2: Generate the characteristic diagram of the negative opening guide vane angle component;

[0008] Step 3: Expand and revise the characteristic diagram of the positive opening guide vane angle component based on engineering experience;

[0009] Step 4: Perform simulation verification based on the characteristic diagram of the guide vane angle component with positive and negative opening.

[0010] Furthermore, the specific steps in step 1 are as follows:

[0011] Step 1-1: Analyze the characteristics of the variable geometry components of the maturely designed variable cycle engine, and obtain the operating point offset coefficient, i.e., the flow offset coefficient k, from the characteristic diagram of the variable geometry components to determine the negative opening degree of the guide vane angle. w Pressure ratio offset coefficient k π Efficiency offset coefficient k η As shown in equation (1)

[0012]

[0013] In the formula, Δα is the change in guide vane angle, and n cor To convert the rotational speed, p i (i = 1, 2, 3) represent different operating points, w represents the flow rate of the variable geometry component at the operating point, π represents the pressure ratio of the variable geometry component at the operating point, η represents the efficiency of the variable geometry component at the operating point, subscript 0 represents the guide vane angle corresponding to the baseline characteristic line, subscript α represents the guide vane angle corresponding to the baseline characteristic line with a change of Δα, and subscript d represents the characteristic diagram of the core drive fan stage component of the maturely designed variable cycle engine.

[0014] Step 1-2: Establish a component operating point offset coefficient model for the negative opening guide vane angle of a variable cycle engine based on a neural network, and select the conversion speed n. cor The change in guide vane angle Δα and the operating point p of the variable geometry component i The labels s corresponding to (i = 1, 2, 3) are used as the input to the neural network, and the flow offset coefficient k w Pressure ratio offset coefficient k π and efficiency offset coefficient k η As the output of the neural network;

[0015] Steps 1-3: Verify the accuracy of the component operating point offset coefficient model of the negative opening guide vane angle of the variable cycle engine by using the characteristics of the variable geometry components of the maturely designed variable cycle engine. Repeatedly adjust the neural network parameters until the accuracy of the offset coefficient neural network model meets the requirements.

[0016] Furthermore, the specific steps in step 2 are as follows:

[0017] Step 2-1: Based on the component operating point offset coefficient model of the negative opening guide vane angle of the variable cycle engine established in Step 1, and according to the converted speed n of the variable geometry component to be designed... cor The change in guide vane angle Δα and the operating point p i (i = 1, 2, 3) to obtain the flow offset coefficient k w Pressure ratio offset coefficient k π and efficiency offset coefficient k η ;

[0018] Step 2-2: Based on the offset coefficient obtained in Step 2-1 and the working point on the reference characteristic line, determine the position of the working point after the negative opening of the guide vane angle changes, as shown in Equation (2).

[0019]

[0020] In the formula, the subscript 0 represents the guide vane angle corresponding to the reference characteristic line, the subscript α represents the guide vane angle corresponding to the reference characteristic line with a change of Δα, w is the flow rate at the working point of the variable geometry component, π is the pressure ratio at the working point of the variable geometry component, and η is the efficiency at the working point of the variable geometry component.

[0021] Steps 2-3: Based on the operating point of the variable geometry component with negative opening guide vane angle, a polynomial fitting of the component characteristic line is used to generate the component characteristic diagram with negative opening guide vane angle.

[0022] Furthermore, the specific steps in step 3 are as follows:

[0023] Step 3-1: Based on the characteristic diagram of the negative opening guide vane angle component generated in Step 2, the flow rate, pressure ratio, and efficiency offset coefficient curves of the variable geometry component guide vane at different equivalent speeds are obtained by least squares fitting. This allows for the extrapolation of the flow rate offset coefficient k at the positive opening guide vane angle component operating point. w Pressure ratio offset coefficient k π and efficiency offset coefficient k η ;

[0024] Step 3-2: Based on the offset coefficient obtained in Step 3-1 and the working point on the reference characteristic line, determine the position of the working point after the offset when the guide vane angle changes positively, as shown in Equation (2);

[0025] Step 3-3: Based on engineering experience, i.e., the efficiency is not greater than 0.9, correct the unreasonable efficiency value of the component's operating point when the guide vane angle changes positively, as shown in equation (3).

[0026] η αc =c η ·η α (3)

[0027] In the formula, c ηη is the efficiency correction factor. αc The efficiency of the working point of the modified variable geometry component;

[0028] Steps 3-4: Based on the operating point of the variable geometry component at the positive opening guide vane angle, a polynomial fitting is used to fit the component characteristic line, thereby generating the component characteristic diagram at the positive opening guide vane angle.

[0029] Furthermore, the specific steps in step 4 are as follows:

[0030] Step 4-1: Import the generated positive and negative opening guide vane angle component characteristic diagram into the variable cycle engine component-level model, give the variable cycle engine control quantity and state quantity, and only change the fuel quantity to simulate the acceleration process of the variable cycle engine.

[0031] Step 4-2: Obtain the position change curve of the operating point of the variable geometry component on the characteristic diagram during the acceleration process of the variable cycle engine, analyze the surge margin change trend caused by the change of guide vane angle, and verify the feasibility of the established variable geometry component characteristics.

[0032] Beneficial Effects: The variable-geometry component characteristic modeling method for a variable-cycle engine based on a reference characteristic line provided by this invention has the following technical advantages compared with existing technologies:

[0033] (1) The variable cycle engine variable geometry component characteristic modeling method based on the reference characteristic line proposed in this invention learns the working point offset law of maturely designed variable geometry components based on neural network, and has a certain generalization ability; and generates a negative opening guide vane angle component characteristic map based on the offset coefficient, which is more complete and more in line with the actual situation of variable geometry components than the existing variable geometry component characteristic correction method.

[0034] (2) The variable cycle engine variable geometry component characteristic modeling method proposed in this invention obtains the positive opening guide vane angle component characteristic diagram based on least squares expansion and engineering experience correction, which further expands the working range of variable geometry components and improves the stability of variable cycle engine model operation. Attached Figure Description

[0035] Figure 1 This is a diagram of the BP neural network topology.

[0036] Figure 2 These are surface plots showing the variation of offset coefficients at different operating points: (a) pressure ratio offset coefficient at surge boundary point, (b) pressure ratio offset coefficient at peak efficiency point, (c) pressure ratio offset coefficient at blockage boundary point, (d) flow rate offset coefficient at surge boundary point, (e) flow rate offset coefficient at peak efficiency point, (f) flow rate offset coefficient at blockage boundary point, (g) efficiency offset coefficient at surge boundary point, (h) efficiency offset coefficient at peak efficiency point, and (i) efficiency offset coefficient at blockage boundary point.

[0037] Figure 3 This is a diagram showing the negative opening guide vane angle pressure ratio flow characteristic.

[0038] Figure 4 This is a flow rate characteristic diagram of negative opening guide vane angle efficiency.

[0039] Figure 5 It is a diagram showing the flow rate characteristics of the guide vane angle pressure ratio with positive and negative opening.

[0040] Figure 6 It is a diagram showing the efficiency-flow characteristics of guide vane angles with positive and negative openings.

[0041] Figure 7 It is a graph showing the change in fuel quantity during acceleration.

[0042] Figure 8 This is a graph showing the change of the operating point when the guide vane angle of the variable geometry component changes. Detailed Implementation

[0043] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] To improve the characteristics of variable geometry components and enhance the stability of the model operation when the guide vane angle of variable geometry components in a variable cycle engine changes, this invention proposes a modeling method for the characteristics of variable geometry components in a variable cycle engine based on a baseline characteristic line. Based on neural networks and least squares, supplemented by mature characteristic laws of variable geometry components transferred from engineering experience, the method rapidly establishes the characteristics of the positive and negative opening guide vane angle components to be designed based on the baseline characteristic line. This improves the operational stability, completeness, and reliability of the component-level model of the variable cycle engine when the guide vane angle of the variable geometry components changes.

[0045] A specific embodiment of the present invention takes the design of a component characteristic modeling method based on a reference characteristic line for the core drive fan stage of a certain type of variable cycle engine with variable guide vane angle as an example. The design of this variable geometry component characteristic modeling method for a variable cycle engine based on a reference characteristic line includes the following steps:

[0046] Step 1: Establish a component operating point offset coefficient model for the negative opening guide vane angle of a variable cycle engine;

[0047] Step 2: Generate the characteristic diagram of the negative opening guide vane angle component;

[0048] Step 3: Expand and revise the characteristic diagram of the positive opening guide vane angle component based on engineering experience;

[0049] Step 4: Perform simulation verification based on the characteristic diagram of the guide vane angle component with positive and negative opening.

[0050] Taking the component characteristic modeling of the core drive fan stage of a certain type of variable cycle engine with variable guide vane angle as an example, the specific steps in step 1 are as follows:

[0051] Step 1-1: Analyze the characteristics of variable geometry components in a maturely designed variable cycle engine. Taking the core drive fan stage as an example, select the operating points of the variable geometry components on its baseline characteristic line: surge boundary point, peak efficiency point, and clogging boundary point, as reference objects. Obtain the operating point offset coefficient, i.e., the flow offset coefficient k, for the change in the negative opening of the guide vane angle in the variable geometry component characteristic diagram. w Pressure ratio offset coefficient k π Efficiency offset coefficient k η As shown in equation (1)

[0052]

[0053] In the formula, Δα is the change in guide vane angle, and n cor To convert the rotational speed, p i (i = 1, 2, 3) represent different operating points, w represents the flow rate of the variable geometry component at the operating point, π represents the pressure ratio of the variable geometry component at the operating point, η represents the efficiency of the variable geometry component at the operating point, subscript 0 represents the guide vane angle corresponding to the baseline characteristic line, subscript α represents the guide vane angle corresponding to the baseline characteristic line with a change of Δα, and subscript d represents the characteristic diagram of the core drive fan stage component of the maturely designed variable cycle engine.

[0054] Step 1-2: Establish a component operating point offset coefficient model for the negative opening guide vane angle of a variable cycle engine based on a neural network, and select the conversion speed n. cor The change in guide vane angle Δα and the operating point p of the variable geometry component i The labels s corresponding to (i = 1, 2, 3) are used as the input to the neural network, and the flow offset coefficient k w Pressure ratio offset coefficient k π and efficiency offset coefficient k η As the output of the neural network, this invention uses the BP neural network algorithm to establish the offset coefficient model, with the topology as follows: Figure 1 As shown in the figure, l i (i = 1, 2, 3) represent network layers, x is the input of the neural network, and y is the output of the neural network. The mapping relationship is shown in equation (2).

[0055]

[0056] In the formula, f(·) is the established offset coefficient neural network model;

[0057] Steps 1-3: Verify the accuracy of the established component operating point offset coefficient model for the negative opening guide vane angle of the variable cycle engine using the characteristics of the variable geometry components of a maturely designed variable cycle engine. Repeatedly adjust the neural network parameters until the accuracy of the offset coefficient neural network model meets the requirements. Finally, determine the number of hidden layers to be 1, the number of hidden layer nodes to be 25, and the flow offset coefficient k for the three operating points. w Pressure ratio offset coefficient k π and efficiency offset coefficient k η With converted speed n cor The relationship between the change in guide vane angle Δα and the following is as follows: Figure 2 As shown in the figure, the offset coefficient is basically monotonic with the changes in the converted rotational speed and the guide vane angle.

[0058] Furthermore, the specific steps in step 2 are as follows:

[0059] Step 2-1: Based on the component operating point offset coefficient model of the negative opening guide vane angle of the variable cycle engine established in Step 1, and according to the converted speed n of the variable geometry component to be designed... cor The change in guide vane angle Δα and the operating point p i (i = 1, 2, 3) to obtain the corresponding flow offset coefficient k w Pressure ratio offset coefficient k π and efficiency offset coefficient k η ;

[0060] Step 2-2: Based on the offset coefficient obtained in Step 2-1 and the working point on the reference characteristic line, determine the position of the working point after the negative opening of the guide vane angle changes, as shown in Equation (3).

[0061]

[0062] In the formula, the subscript 0 represents the guide vane angle corresponding to the reference characteristic line, the subscript α represents the guide vane angle corresponding to the reference characteristic line with a change of Δα, w is the flow rate at the working point of the variable geometry component, π is the pressure ratio at the working point of the variable geometry component, and η is the efficiency at the working point of the variable geometry component.

[0063] Steps 2-3: Based on the operating point of the variable geometry component with negative guide vane angle, a polynomial is used to fit the component characteristic curve. Taking the pressure ratio-flow characteristic diagram as an example, let the fitting polynomial be...

[0064]

[0065] In the formula, a0, a1, ..., a k Let be the polynomial coefficients. Find the polynomial coefficients that satisfy .

[0066]

[0067] In the formula, w is the operating point flow rate, π is the operating point pressure ratio, and n is the number of operating points. Since the number of operating points is less than the polynomial order, the polynomial coefficients are not unique. The polynomial coefficients obtained through adjustment are used to smooth the component characteristic lines, thereby generating the negative opening guide vane angle component characteristic diagram. The final pressure ratio-flow characteristic diagram is shown below. Figure 3 As shown in the figure, the efficiency-flow characteristic diagram is as follows: Figure 4 As shown.

[0068] Furthermore, the specific steps in step 3 are as follows:

[0069] Step 3-1: Based on the characteristic diagram of the negative opening guide vane angle component generated in Step 2, the flow rate, pressure ratio, and efficiency offset coefficient curves of the variable geometry component guide vane at different equivalent speeds are obtained by least squares fitting. This allows for the extrapolation of the flow rate offset coefficient k at the positive opening guide vane angle component operating point. w Pressure ratio offset coefficient k π and efficiency offset coefficient k η Taking the surge boundary point p1 on a certain converted speed characteristic line as an example, the flow rate, pressure ratio, and efficiency offset coefficients at different negative guide vane angles corresponding to this operating point can be obtained from the neural network offset coefficient model. Let the fitting polynomial be...

[0070]

[0071] In the formula, The coefficients are the fitting polynomials for the flow offset coefficients. The coefficients are the fitting polynomials for the pressure ratio offset coefficient. The coefficients of the fitting polynomial for the efficiency offset coefficients are obtained, and the polynomial coefficients are calculated to satisfy the following conditions.

[0072]

[0073] In the formula, m is the number of guide vane angles with different opening degrees. Based on the fitted polynomial, the flow rate, pressure ratio, and efficiency offset coefficients corresponding to the positive opening degree guide vane angle can be obtained;

[0074] Step 3-2: Based on the offset coefficient obtained in Step 3-1 and the working point on the reference characteristic line, determine the position of the working point after the offset when the guide vane angle changes positively, as shown in Equation (3);

[0075] Step 3-3: Based on engineering experience, i.e., the efficiency is not greater than 0.9, correct the unreasonable efficiency value of the component's operating point when the guide vane angle changes positively, as shown in equation (8).

[0076] η αc =c η ·η α (8)

[0077] In the formula, c ηη is the efficiency correction factor. αc The efficiency of the working point of the modified variable geometry component;

[0078] Steps 3-4: Based on the operating point of the variable geometry component with a positive guide vane angle, a polynomial fitting is used to fit the component characteristic curve, thereby generating the component characteristic diagram with a positive guide vane angle. The component pressure ratio and flow rate characteristic diagrams with positive and negative guide vane angles are shown below. Figure 5 As shown in the figure, the efficiency-flow characteristic diagram is as follows: Figure 6 As shown.

[0079] Furthermore, the specific steps in step 4 are as follows:

[0080] Step 4-1: Import the generated positive and negative opening guide vane angle component characteristic diagrams into the variable cycle engine component-level model. Taking the single-bypass variable cycle engine mode as an example, given the control and state variables of the variable cycle engine, only change the fuel quantity to simulate the acceleration process of the variable cycle engine. The fuel quantity change curve is shown below. Figure 7 As shown in the figure, the fuel values ​​have been normalized based on the fuel quantity at the single bypass design point of the variable cycle engine.

[0081] Step 4-2: Obtain the position change curve of the component's operating point on the characteristic diagram during the acceleration process of the variable cycle engine when the guide vane angle changes, such as... Figure 8 As shown in the figure, at the same converted speed, the surge margin of the variable geometry component increases with the negative opening of the guide vane angle, and decreases with the positive opening of the guide vane angle. This demonstrates that the variable geometry component characteristic modeling method based on the baseline characteristic line can reflect the characteristics of the variable geometry component. During engine operation, adjusting the guide vane angle of the variable geometry component can effectively adjust the surge margin of the component while ensuring engine performance.

[0082] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method of modeling variable geometry component characteristics for a variable cycle engine based on a reference characteristic line, the method comprising: The method comprises the following steps: Step 1: establishing a component working point offset coefficient model of the negative opening guide vane angle of the variable cycle engine; Step 2: generating a component characteristic map of the negative opening guide vane angle; Step 3: extending and correcting the component characteristic map of the positive opening guide vane angle according to engineering experience; Step 4: simulating and verifying based on the component characteristic maps of the positive and negative opening guide vane angles. The component working point offset coefficient model of the negative opening guide vane angle in the step 1 is established according to the following steps: Step 1-1: Analyzing the variable geometry component characteristics of the already matured design of the variable cycle engine, obtaining the working point offset coefficient, i.e. the flow rate offset coefficient, of the guide vane angle negative opening change in the variable geometry component characteristic diagram , the pressure ratio offset coefficient , the efficiency offset coefficient , as shown in the following formula ； wherein, is the guide vane angle change, is the converted speed, is the different operating points, is the flow of the variable geometry component operating point, is the pressure ratio of the variable geometry component operating point, is the efficiency of the variable geometry component operating point, subscript 0 represents the guide vane angle corresponding to the reference characteristic line, subscript represents the guide vane angle corresponding to the guide vane angle change of the reference characteristic line, subscript is the variable cycle engine core driving fan stage component characteristic map of the mature design; Step 1-2: Establishing a variable cycle engine negative opening guide vane angle component working point offset coefficient model based on a neural network, selecting a conversion speed , a guide vane angle change amount , and a variable geometry component working point corresponding labels as inputs to the neural network, a flow offset coefficient , a pressure ratio offset coefficient , and an efficiency offset coefficient as outputs of the neural network; Step 1-3: verifying the precision of the established component working point offset coefficient model of the negative opening guide vane angle of the variable cycle engine by using the variable geometry component characteristics of the mature designed variable cycle engine, and repeatedly adjusting the neural network parameters until the precision of the offset coefficient neural network model reaches the requirement.

2. A method of modeling variable geometry component characteristics of a variable cycle engine based on a reference characteristic line according to claim 1, characterized in that: The specific steps of generating the component characteristic map of the negative opening guide vane angle in the step 2 are as follows: Step 2-1: Based on the variable cycle engine negative opening guide vane angle component working point offset coefficient model, according to the conversion speed of the variable geometry component to be designed , guide vane angle change amount and working point Flow offset coefficient , pressure ratio offset coefficient and efficiency offset coefficient ; Step 2-2: determining the position of the working point after offset according to the offset coefficient and the working point on the reference characteristic line obtained in the step 2-1 when the negative opening guide vane angle changes, as shown in the following formula ； Step 2-3: generating the component characteristic map of the negative opening guide vane angle by using polynomial fitting of the working point when the negative opening guide vane angle of the variable geometry component changes.

3. A method of modeling variable geometry component characteristics of a variable cycle engine based on a reference characteristic line according to claim 2, characterized in that: The specific steps of extending and correcting the component characteristic map of the positive opening guide vane angle according to engineering experience in the step 3 are as follows: Step 3-1: According to the negative opening guide vane angle component characteristic map, the flow rate, pressure ratio, and efficiency offset coefficient curves of different conversion speed working points when the guide vane changes are fitted based on the least square fitting, so as to obtain the flow rate offset coefficient of the positive opening guide vane angle component working point , the pressure ratio offset coefficient , and the efficiency offset coefficient ; Step 3-2: determining the position of the working point after offset according to the offset coefficient and the working point on the reference characteristic line obtained in the step 3-1 when the positive opening guide vane angle changes, as shown in the formula (2); Step 3-3: correcting the unreasonable efficiency value of the working point of the variable geometry component when the positive opening guide vane angle changes according to the engineering experience that the efficiency is not greater than 0.9, as shown in the following formula ； In the formula, is the efficiency correction factor, is the corrected efficiency of the variable geometry component operating point; Step 3-4: generating the component characteristic map of the positive opening guide vane angle by using polynomial fitting of the working point when the positive opening guide vane angle of the variable geometry component changes.

4. A method of modeling variable geometry component characteristics of a variable cycle engine based on a reference characteristic line as recited in claim 1, characterized by: The specific steps of simulating and verifying based on the component characteristic maps of the positive and negative opening guide vane angles in the step 4 are as follows: Step 4-1: importing the generated component characteristic maps of the positive and negative opening guide vane angles into the component level model of the variable cycle engine, giving the control quantity and state quantity of the variable cycle engine, and only changing the fuel quantity to simulate the acceleration process of the variable cycle engine for simulation; Step 4-2: obtaining the position change curve of the working point of the variable geometry component on the characteristic map in the acceleration process of the variable cycle engine, analyzing the trend of the surge margin change caused by the guide vane angle change, and verifying the feasibility of the established variable geometry component characteristics.

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