An optimization design method and system for isolation sections based on FFD method

Abstract

The present invention discloses an optimization design method and system of an isolation section based on the FFD method, the method comprising: based on the shape of the air inlet outlet and the combustion chamber inlet, by adjusting the flow area change law in the isolation section, the first aerodynamic performance optimization of the isolation section shape is performed to obtain the discrete points of the initial isolation section; a cuboid that completely envelops the isolation section is divided in the local coordinate system, and a number of evenly distributed control points are selected on the cuboid to form a control point grid; the local coordinates of each control point in the control point grid are used as variables, and the total pressure recovery coefficient of the isolation section is used as the optimization target, and the global optimization algorithm is used to perform the second aerodynamic performance optimization, and the discrete points of the isolation section with the best aerodynamic performance are obtained, and a three-dimensional entity is generated. The present invention is applied to the field of hypersonic aircraft technology, and can significantly improve the total pressure recovery coefficient of the isolation section outlet. For hypersonic aircraft where every centimeter counts, the optimization effect is very considerable.

Description

Technical Field

[0001] The present invention relates to the technical field of hypersonic aircraft, and particularly to the field of isolation section design of an air-breathing hypersonic aircraft engine, and specifically to an optimization design method and system for an isolation section based on an FFD method. Background Art

[0002] Hypersonic aircraft refers to a new type of aircraft that flies at a speed exceeding five times the speed of sound. Its development has received extensive attention and in-depth research. The mass of the oxidizer carried by non-air-breathing hypersonic aircraft accounts for most of the take-off weight, while its effective load accounts for a very small proportion. Therefore, from the perspective of economy alone, the development of air-breathing hypersonic flight is inevitable.

[0003] For air-breathing hypersonic vehicles, the isolation section is an important component of its power system. It also separates the air inlet from the combustion chamber to prevent the combustion chamber from interfering with the air inlet. There are different design methods for isolation sections of different configurations.

[0004] For straight isolators, the flow mechanism of shock waves, expansion waves and boundary layers is relatively clear, so some semi-empirical formulas that can guide the design of straight isolators are proposed. For curved isolators, the main methods include a cross-sectional shape generation and transition technology based on curvature control proposed in the literature "A design method for complex variable cross-section inlet", a supersonic turning flow channel design method proposed in the literature "Supersonic turning flow channel design method", and a three-dimensional curved variable cross-section flow channel design method based on geometric fusion proposed in the literature "A hypersonic isolator optimization design method and system".

[0005] In the above-mentioned existing isolation section design methods, engineers mostly "draw" the corresponding shape through 3D modeling software such as Solidworks, CATIA, etc., and then use commercial software to perform meshing and fluid mechanics simulation to obtain its performance, which is extremely time-consuming; some existing technologies have also proposed parametric design methods for isolation sections, but lack an understanding of the aerodynamic characteristics of pipeline flow, which easily limits the types of generated configurations. Summary of the invention

[0006] In view of the deficiencies in the above-mentioned prior art, the present invention provides an optimization design method and system for an isolation section based on the FFD method. Compared with the original isolation section, the total pressure recovery coefficient at the isolation section outlet can be significantly improved. For hypersonic aircraft where every centimeter counts, the optimization effect is very considerable.

[0007] To achieve the above object, the present invention provides an optimization design method for an isolation segment based on an FFD method, comprising the following steps:

[0008] Step 1: Based on the shapes of the inlet port outlet and the combustion chamber inlet, the first aerodynamic performance optimization is performed using CFD cycle simulation to obtain the discrete points of the initial isolation section;

[0009] Step 2: convert the discrete points of the initial isolation segment from the global coordinate system to the local coordinate system, and divide a cuboid that completely envelops the isolation segment in the local coordinate system based on the overall size of the isolation segment, and select a number of evenly distributed control points on the cuboid to form a control point grid;

[0010] Step 3, taking the local coordinates of each control point in the control point grid as variables and the total pressure recovery coefficient of the isolation section as the optimization target, a global optimization algorithm is used to perform a second aerodynamic performance optimization, obtain the isolation section discrete points with the best aerodynamic performance, and further obtain the isolation section surface grid with the best aerodynamic performance;

[0011] Step 4, import the surface mesh of the isolation section with the best aerodynamic performance into CATIA software to intercept the contour lines at different geometric positions, and then loft the contour lines in sequence to generate smooth surfaces and three-dimensional entities to obtain the final configuration of the isolation section.

[0012] As a further improvement of the above technical solution, step 1 specifically includes:

[0013] Step 1.1, extract the shapes of the inlet duct outlet and the combustion chamber inlet, and perform numerical discretization to obtain the coordinates of discrete points representing the shapes of the inlet and outlet of the isolation section;

[0014] Step 1.2, based on the coordinates of the discrete points at the inlet and outlet of the isolation section, the initial coordinates of the discrete points of each section along the isolation section are obtained by using the geometric fusion method, and the initial value of the area of ​​each section along the isolation section is obtained by integrating the initial coordinates of the discrete points of each section along the isolation section;

[0015] Step 1.3, constructing a cross-sectional area variation model along the isolation section having at least one control parameter, and obtaining the area design value of each cross section along the isolation section based on the cross-sectional area variation model along the isolation section;

[0016] Step 1.4, obtaining the scaling factor of each section along the course based on the initial area value and the design area value of each section along the course, and obtaining the final coordinates of the discrete points of each section along the course based on the scaling factor of each section along the course and the initial coordinates of the discrete points, that is, obtaining the discrete points of the entire isolation section;

[0017] Step 1.5, express the discrete points of the entire isolation section in STL format and import them into the meshing software for CFD cyclic simulation. Take the total pressure recovery coefficient of the isolation section as the optimization target, and use the optimization algorithm to change the value of the control parameter until the simulation optimization target converges, that is, the discrete points of the initial isolation section are obtained.

[0018] As a further improvement of the above technical solution, in step 1.2, the initial coordinates of the discrete points of each section along the isolation section are obtained by using the geometric fusion method, specifically:

[0019] For the i-th along-the-line section of the isolation segment, its along-the-line coordinate is x(i), that is, the x-axis coordinate of each discrete point in the i-th along-the-line section is x(i), and the corresponding y-axis coordinate and z-axis coordinate are:

[0020] y(i,j)=(1-k i )·y in (j)+k i ·y in (j)

[0021] z(i,j)=(1-k i )·z in (j)+k i ·z in (j)

[0022]

[0023] Where y(i,j) is the y-axis coordinate of the j-th discrete point in the i-th section along the process, z(i,j) is the z-axis coordinate of the j-th discrete point in the i-th section along the process, and k i is the fusion coefficient of the i-th section along the process, y in (j) is the y-axis coordinate of the jth discrete point in the inlet outlet section, z in (j) is the z-axis coordinate of the jth discrete point in the inlet outlet cross section, x in is the x-axis coordinate of the inlet duct outlet section, x out The x-axis coordinate of the combustion chamber inlet section;

[0024] That is, the initial coordinates of the jth discrete point in the i-th section along the way are: (x(i), y(i,j), z(i,j)).

[0025] As a further improvement of the above technical solution, in step 1.3, the cross-sectional area variation model of the isolation section along the way is specifically:

[0026]

[0027] In the formula, A i represents the design value of the area of ​​the i-th section along the way, A in Indicates the area of ​​the inlet duct outlet cross section, A out It represents the area of ​​the combustion chamber inlet section, n represents the total number of sections along the way used to describe the shape of the isolation section, and a and b are control parameters.

[0028] As a further improvement of the above technical solution, in step 1.4, the process of obtaining the final coordinates of the discrete points of each along-the-cross section is specifically as follows:

[0029] Divide the initial value of the area of ​​the i-th section along the process by the design value and take the square root to obtain the scaling factor p(i) of the i-th section along the process;

[0030] The final coordinates of the jth discrete point in the i-th section along the way are: (x(i), p(i)·y(i,j), p(i)·z(i,j)).

[0031] As a further improvement of the above technical solution, the optimization algorithm described in step 1.5 is used to change the value of the control parameter until the simulation optimization target converges, specifically:

[0032] The gradient optimization algorithm is used to change the values ​​of the control parameters until the simulation optimization goal converges.

[0033] As a further improvement of the above technical solution, in step 2, the discrete points of the initial isolation segment are converted from the global coordinate system to the local coordinate system, specifically:

[0034] Set the global coordinate system to O-XYZ, and its coordinate axis origin O is (0,0,0) in the global coordinate system; set the local coordinate system to O′-STU, and its coordinate axis origin O′ is X0(x0,y0,z0) in the global coordinate system. The coordinates of any point on the isolation segment in the local coordinate system are x(s,t,u), and the coordinates in the global coordinate system are X(x,y,z), then:

[0035] X(x,y,z)=X0(x0,y0,z0)+s·S+t·T+u·U

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] Where S, T, U are the unit vectors of the local coordinate system axis; C o,p,qrepresents the local coordinates of the oth control point in the s direction, the pth control point in the t direction, and the qth control point in the u direction in the local coordinate system; l, m, n represent the order of the FFD equation, l+1, m+1, n+1 represent the number of control points in the s, t, and u directions respectively, and l, m, n are positive integers; B o (s), B p (t) and B q (u) represents the Bernstein basis functions in the s, t, and u directions respectively.

[0044] To achieve the above objectives, the present invention also provides an optimization design system for isolation segments based on the FFD method, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0045] Compared with the prior art, the optimization design method and system of the isolation segment based on the FFD method provided by the present invention has the following beneficial technical effects:

[0046] 1. The present invention proposes a geometric fusion method with controllable cross-sectional area using a gradient algorithm to obtain an isolation segment configuration with better performance as the basic configuration of the FFD optimization design method, which can effectively save optimization time;

[0047] 2. The present invention proposes for the first time to use the FFD method to parametrically express the hypersonic isolation section, and builds an optimization platform based on the global optimization algorithm. Compared with the original isolation section, the total pressure recovery coefficient at the isolation section outlet can be significantly improved. For hypersonic aircraft where every millimeter counts, the optimization effect is very considerable. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0049] Figure 1 Schematic diagram of the process of optimizing the design method of the isolation segment based on the FFD method in an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a process flow of the first aerodynamic performance optimization in an embodiment of the present invention;

[0051] Figure 3 Schematic diagram of discrete points of the inlet and outlet of the isolation section in an embodiment of the present invention;

[0052] Figure 4Schematic diagram of discrete points along the cross section of the isolation section in an embodiment of the present invention;

[0053] Figure 5 A schematic diagram of a grid of the isolation section during the first aerodynamic performance optimization in an embodiment of the present invention;

[0054] Figure 6 Schematic diagram of conversion between the global coordinate system and the local coordinate system in an embodiment of the present invention;

[0055] Figure 7 Schematic diagram of the positions of the control point grid and the isolation segment in the local coordinate system in an embodiment of the present invention;

[0056] Figure 8 A schematic diagram of a grid of an isolation section in the early stage of the second aerodynamic performance optimization in an embodiment of the present invention;

[0057] Fig. 9 A schematic diagram of a grid of an isolation section in a later stage of the second aerodynamic performance optimization in an embodiment of the present invention;

[0058] Fig.10 Schematic diagram for comparing total pressure recovery coefficients in embodiments of the present invention.

[0059] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0062] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0063] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0065] like Figure 1 The figure shows an optimization design method of an isolation segment based on the FFD method disclosed in this embodiment, which specifically includes the following steps 1-4.

[0066] Step 1: Based on the shapes of the inlet port outlet and the combustion chamber inlet, the first aerodynamic performance optimization is performed using CFD cycle simulation to obtain the discrete points of the initial isolation section.

[0067] In this embodiment, firstly, according to the shape constraints of the inlet and outlet of the isolation section and the change law of the isolation section area, the geometry fusion method is used to parametrically express the isolation section shape to obtain the initial isolation section profile. Then, CFD software is used for cyclic simulation, and the optimization algorithm is used to adjust the value of the control parameter until the simulation optimization target converges, and finally the discrete points of the initial isolation section are obtained. Figure 2 The specific implementation process includes the following steps 1.1-1.5.

[0068] Step 1.1, extract the shapes of the inlet port outlet and the combustion chamber inlet, and perform numerical discretization to obtain the coordinates of the discrete points representing the shapes of the inlet and outlet of the isolation section, that is, Figure 3 As shown, the rectangular discrete points are the inlet duct outlets, that is, the inlet discrete points of the isolation section, and the circular discrete points are the combustion chamber inlet, that is, the outlet discrete points of the isolation section.

[0069] Step 1.2, based on the coordinates of the discrete points at the entrance and exit of the isolation section, the initial coordinates of the discrete points of each section along the isolation section are obtained by using the geometric fusion method, and the initial value of the area of ​​each section along the isolation section is obtained by integrating the initial coordinates of the discrete points of each section along the isolation section. The specific implementation process of using the geometric fusion method to obtain the initial coordinates of the discrete points of each section along the isolation section is as follows:

[0070] refer to Figure 4 , for the i-th along-the-line section of the isolation segment, its along-the-line coordinate is x(i), that is, the x-axis coordinate of each discrete point in the i-th along-the-line section is x(i), and the corresponding y-axis coordinate and z-axis coordinate are:

[0071] y(i,j)=(1-k i )·y in (j)+k i ·y in (j)

[0072] z(i,j)=(1-k i )·z in (j)+k i ·z in (j)

[0073]

[0074] Where y(i,j) is the y-axis coordinate of the j-th discrete point in the i-th section along the process, z(i,j) is the z-axis coordinate of the j-th discrete point in the i-th section along the process, and k i is the fusion coefficient of the i-th section along the process, y in (j) is the y-axis coordinate of the jth discrete point in the inlet outlet section, z in (j) is the z-axis coordinate of the jth discrete point in the inlet outlet cross section, x in is the x-axis coordinate of the inlet duct outlet section, x out The x-axis coordinate of the combustion chamber inlet section;

[0075] That is, the initial coordinates of the jth discrete point in the i-th section along the process are obtained as: (x(i), y(i,j), z(i,j)). As for how to integrate the initial coordinates of the discrete points of each section along the process to obtain the initial value of the area of ​​each section along the process, it is a conventional integration method, so it will not be repeated in this embodiment.

[0076] Step 1.3, constructing a cross-sectional area variation model along the isolation section with at least one control parameter, and obtaining the area design value of each cross section along the isolation section based on the cross-sectional area variation model along the isolation section. In this embodiment, the control parameters in the cross-sectional area variation model along the isolation section are designed to be two, specifically:

[0077]

[0078] In the formula, A i represents the design value of the area of ​​the i-th section along the way, A in Indicates the area of ​​the inlet duct outlet cross section, A outIt represents the area of ​​the combustion chamber inlet section, n represents the total number of sections along the way used to describe the shape of the isolation section, and a and b are control parameters.

[0079] Step 1.4, based on the initial area value and the design area value of each section along the way, the scaling factor of each section along the way is obtained, and based on the scaling factor of each section along the way and the initial coordinates of the discrete points, the final coordinates of the discrete points of each section along the way are obtained, that is, the discrete points of the entire isolation section are obtained. The specific process of obtaining the final coordinates of the discrete points of each section along the way is:

[0080] Divide the initial value of the area of ​​the i-th section along the process by the design value and take the square root to obtain the scaling factor p(i) of the i-th section along the process;

[0081] The final coordinates of the jth discrete point in the i-th section along the way are: (x(i), p(i)·y(i,j), p(i)·z(i,j)).

[0082] Step 1.5, express the discrete points of the entire isolation segment in STL format. The specific implementation process is as follows:

[0083] The ASCII format of STL is as follows:

[0084] solid isolator / / file path and file name

[0085] facet normal xyz / / Three component values ​​of the normal vector of the triangle face

[0086] outer loop

[0087] vertex xyz∥The coordinates of the first vertex of the triangle

[0088] vertex xyz / / Coordinates of the second vertex of the triangle

[0089] vertex xyz∥The coordinates of the third vertex of the triangle

[0090] endloop

[0091] endfacet / / The first triangle is defined

[0092] …

[0093] …

[0094] endsolid isolator∥The entire file ends.

[0095] Then, the discrete points of the isolation section as a whole expressed in STL format are imported into the meshing software and CFD cycle simulation is performed to obtain the aerodynamic performance of the isolation section, that is, Figure 5 As shown. The total pressure recovery coefficient is a generally accepted performance metric for the compression components of the propulsion system. It can accurately measure the size of the flow loss in the flow process. The larger the total pressure recovery coefficient, the smaller the flow loss; conversely, the greater the flow loss. Therefore, taking a and b in the cross-sectional area change model of the isolation section as variables, and the total pressure recovery coefficient of the isolation section as the optimization target, the gradient optimization algorithm is used to change the values ​​of a and b until the simulation optimization target converges, thereby obtaining the isolation section with the best aerodynamic performance, that is, obtaining the discrete points of the initial isolation section after the first aerodynamic performance optimization.

[0096] Step 2: Convert the discrete points of the initial isolation segment from the global coordinate system to the local coordinate system, and divide a cuboid that completely envelops the isolation segment in the local coordinate system based on the overall size of the isolation segment, and select a number of evenly distributed control points on the cuboid to form a control point grid. The specific implementation process is as follows:

[0097] refer to Figure 6 , set the global coordinate system to O-XYZ, and its coordinate axis origin O is (0,0,0) in the global coordinate system; set the local coordinate system to O′-STU, and its coordinate axis origin O′ is X0 (x0, y0, z0) in the global coordinate system, and create a control point grid to embed the isolation segment into this framework, that is, Figure 7 As shown. The coordinates of any point on the isolation segment in the local coordinate system are x(s,t,u), and the coordinates in the global coordinate system are X(x,y,z), then:

[0098] X(x,y,z)=X0(x0,y0,z0)+s·S+t·T+u·U

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] Where S, T, U are the unit vectors of the local coordinate system axes, and 0≤s≤1, 0≤t≤1, 0≤u≤1; C o,p,qrepresents the local coordinates of the oth control point in the s direction, the pth control point in the t direction, and the qth control point in the u direction in the local coordinate system; l, m, n represent the order of the FFD equation, l+1, m+1, n+1 represent the number of control points in the s, t, and u directions respectively, and l, m, n are positive integers; B o (s), B p (t) and B q (u) represents the Bernstein basis functions in the s, t, and u directions respectively.

[0107] Step 3: The movement of the control points in the control point grid will cause the geometric shape of the internal isolation segment to deform smoothly. The local coordinates of each control point in the control point grid are used as variables, and the total pressure recovery coefficient of the isolation segment is used as the optimization target. The global optimization algorithm is used to perform a second aerodynamic performance optimization to obtain the STL format file of the discrete points of the isolation segment with the best aerodynamic performance. The meshing and calculation solutions of the iterative process will also be automatically completed, that is, Figure 8-9 As shown;

[0108] Step 4, import the surface mesh of the isolation section with the best aerodynamic performance into CATIA software to intercept the contour lines at different geometric positions, and then loft the contour lines in sequence to generate smooth surfaces and three-dimensional entities to obtain the final configuration of the isolation section.

[0109] In a specific example, the method of this embodiment is used to optimize a certain type of hypersonic isolation section. Fig.10 , where the ordinate is the total pressure recovery coefficient, from Fig.10 It can be seen that, compared with the original isolation section, the total pressure recovery coefficient at the isolation section outlet after optimization using this embodiment is increased by 3%. For hypersonic aircraft where every inch counts, the optimization effect is very significant.

[0110] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An optimization design method for an isolation segment based on the FFD method, characterized in that: The steps include: Step 1: Based on the shapes of the inlet port outlet and the combustion chamber inlet, the first aerodynamic performance optimization is performed using CFD cycle simulation to obtain the discrete points of the initial isolation section; Step 2: convert the discrete points of the initial isolation segment from the global coordinate system to the local coordinate system, and divide a cuboid that completely envelops the isolation segment in the local coordinate system based on the overall size of the isolation segment, and select a number of evenly distributed control points on the cuboid to form a control point grid; Step 3, taking the local coordinates of each control point in the control point grid as variables and the total pressure recovery coefficient of the isolation section as the optimization target, a global optimization algorithm is used to perform a second aerodynamic performance optimization, obtain the isolation section discrete points with the best aerodynamic performance, and further obtain the isolation section surface grid with the best aerodynamic performance; Step 4, import the surface mesh of the isolation section with the best aerodynamic performance into CATIA software to intercept the contour lines at different geometric positions, and then loft the contour lines in sequence to generate smooth surfaces and three-dimensional entities to obtain the final configuration of the isolation section.

2. The optimization design method of the isolation segment based on the FFD method according to claim 1 is characterized in that: Step 1 specifically includes: Step 1.1, extract the shapes of the inlet duct outlet and the combustion chamber inlet, and perform numerical discretization to obtain the coordinates of discrete points representing the shapes of the inlet and outlet of the isolation section; Step 1.2, based on the coordinates of the discrete points at the inlet and outlet of the isolation section, the initial coordinates of the discrete points of each section along the isolation section are obtained by using the geometric fusion method, and the initial value of the area of ​​each section along the isolation section is obtained by integrating the initial coordinates of the discrete points of each section along the isolation section; Step 1.3, constructing a cross-sectional area variation model along the isolation section having at least one control parameter, and obtaining the area design value of each cross section along the isolation section based on the cross-sectional area variation model along the isolation section; Step 1.4, obtaining the scaling factor of each section along the course based on the initial area value and the design area value of each section along the course, and obtaining the final coordinates of the discrete points of each section along the course based on the scaling factor of each section along the course and the initial coordinates of the discrete points, that is, obtaining the discrete points of the entire isolation section; Step 1.5, express the discrete points of the entire isolation section in STL format and import them into the meshing software for CFD cyclic simulation. Take the total pressure recovery coefficient of the isolation section as the optimization target, and use the optimization algorithm to change the value of the control parameter until the simulation optimization target converges, that is, the discrete points of the initial isolation section are obtained.

3. The optimization design method of the isolation segment based on the FFD method according to claim 2 is characterized in that: In step 1.2, the geometric fusion method is used to obtain the initial coordinates of the discrete points of each section along the isolation section, specifically: For the i-th along-the-line section of the isolation segment, its along-the-line coordinate is x(i), that is, the x-axis coordinate of each discrete point in the i-th along-the-line section is x(i), and the corresponding y-axis coordinate and z-axis coordinate are: y(i,j)=(1-k i )·y in (j)+k i ·y in (j) z(i,j)=(1-k i )·z in (j)+k i ·z in (j) Where y(i,j) is the y-axis coordinate of the j-th discrete point in the i-th section along the process, z(i,j) is the z-axis coordinate of the j-th discrete point in the i-th section along the process, and k i is the fusion coefficient of the i-th section along the process, y in (j) is the y-axis coordinate of the jth discrete point in the inlet outlet section, z in (j) is the z-axis coordinate of the jth discrete point in the inlet outlet cross section, x in is the x-axis coordinate of the inlet duct outlet section, x out The x-axis coordinate of the combustion chamber inlet section; That is, the initial coordinates of the jth discrete point in the i-th section along the way are: (x(i), y(i,j), z(i,j)).

4. The optimization design method of the isolation segment based on the FFD method according to claim 3 is characterized in that: In step 1.3, the cross-sectional area variation model of the isolation section along the way is specifically: In the formula, A i represents the design value of the area of ​​the i-th section along the way, A in Indicates the area of ​​the inlet duct outlet cross section, A out It represents the area of ​​the combustion chamber inlet section, n represents the total number of sections along the way used to describe the shape of the isolation section, and a and b are control parameters.

5. The optimization design method of the isolation segment based on the FFD method according to claim 4 is characterized in that: In step 1.4, the process of obtaining the final coordinates of the discrete points along the cross section is as follows: Divide the initial value of the area of ​​the i-th section along the process by the design value and take the square root to obtain the scaling factor p(i) of the i-th section along the process; The final coordinates of the jth discrete point in the i-th section along the way are: (x(i), p(i)·y(i,j), p(i)·z(i,j)).

6. The optimization design method of the isolation segment based on the FFD method according to any one of claims 2 to 5, characterized in that: Step 1.5 uses the optimization algorithm to change the value of the control parameter until the simulation optimization target converges, specifically: The gradient optimization algorithm is used to change the values ​​of the control parameters until the simulation optimization goal converges.

7. The optimization design method of the isolation segment based on the FFD method according to any one of claims 1 to 5, characterized in that: In step 2, the discrete points of the initial isolation segment are converted from the global coordinate system to the local coordinate system, specifically: Set the global coordinate system to O-XYZ, and its coordinate axis origin O is (0,0,0) in the global coordinate system; set the local coordinate system to O′-STU, and its coordinate axis origin O′ is X0(x0,y0,z0) in the global coordinate system. The coordinates of any point on the isolation segment in the local coordinate system are x(s,t,u), and the coordinates in the global coordinate system are X(x,y,z), then: X(x,y,z)=X0(x0,y0,z0)+s·S+t·T+u·U Where S, T, U are the unit vectors of the local coordinate system axis; C o,p,q represents the local coordinates of the oth control point in the s direction, the pth control point in the t direction, and the qth control point in the u direction in the local coordinate system; l, m, n represent the order of the FFD equation, l+1, m+1, n+1 represent the number of control points in the s, t, and u directions respectively, and l, m, n are positive integers; B o (s), B p (t) and B q (u) represents the Bernstein basis functions in the s, t, and u directions respectively.

8. An optimization design system for isolation segments based on the FFD method, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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