A three-dimensional S-shaped curved concave flow channel design method and system

Abstract

The present invention discloses a three-dimensional S-shaped curved concave flow channel design method and system. The design method includes the following steps: obtaining the flow channel inlet and outlet profiles of a supersonic ramjet flow channel; extracting an integer number of discrete points N along the circumference of each of the inlet and outlet profiles to form N sets of inlet and outlet discrete point pairs; setting the variation pattern of S-shaped curve parameters along the circumference of the flow channel inlet and outlet profiles to obtain N S-curves; obtaining a set of N*M discrete point coordinates on the curve set using M parallel intercepting planes; generating an S-shaped surface by enveloping, calculating the area of ​​the two-dimensional cross-sectional figure, obtaining the variation pattern of the flow channel cross-sectional area along the flow direction and the variation pattern of the slope of the center curve of the S-shaped surface; and determining whether the design is reasonable. The present invention can be applied to computer-aided design of flow channels transitioning from various shapes, including irregular shapes, to circular or elliptical shapes, and can also meet the needs of flow channel design with offset inlet and outlet positions.

Description

Technical Field

[0001] The present invention belongs to the technical field of computer-aided design, and in particular relates to a design method and system for a three-dimensional S-shaped curved concave flow channel. Background Art

[0002] The scramjet engine is mainly composed of an air inlet, an isolation section, and a combustion chamber. The isolation section is located between the air inlet and the combustion chamber. It decelerates and pressurizes the incoming flow captured by the air inlet through a shock wave train, providing the combustion chamber with an airflow that meets the combustion requirements, while reducing the impact of the isolation combustion chamber back pressure on the upstream flow. There are many types of isolation section flow channels. According to the geometric shape, they can be divided into straight flow channels and curved flow channels; from the cross-sectional shape, they can include circular flow channels, rectangular flow channels, and special-shaped flow channels; from the law of area change, they can be classified as expansion flow channels and contraction flow channels, etc. Under the current constraints of aircraft aerodynamic design, it is necessary to generate a three-dimensional special-shaped isolation section with different inlet and outlet shapes and an offset cross-sectional center, which poses a challenge to the isolation section design.

[0003] Predecessors have conducted relatively extensive research on the design of isolation sections. Among them, the Chinese invention patent with the announcement number CN110210185A: A method and system for optimizing the design of hypersonic isolation sections, which adopts a method based on geometric fusion for flow channel design, and includes simulation optimization of the flow channel. This method can simultaneously meet the shape and offset requirements of the inlet and outlet, but it is difficult to directly control the change in the circumferential curvature of the flow channel under the offset condition. The Chinese invention patent with the announcement number CN102996581A: A method for designing supersonic turning flow channels, which combines the inlet parameters with the characteristic line method, reversely derives the corresponding side wall profile from the given single-side wall profile, and constructs a flow channel geometric configuration that meets the supersonic flow requirements based on the inversion of the flow characteristic parameters at the outlet, but the characteristic line method is very complex and computationally intensive when facing three-dimensional configurations. The Chinese invention patent with announcement number CN114564817A: A design method for a fan-shaped inlet to rectangular outlet isolation section, which can achieve a smooth transition of the inlet and outlet cross-sections by smoothly transitioning the inlet fan-shaped height, arc length and fan-shaped angle to the corresponding height, arc length and fan-shaped angle of the outlet rectangle. However, there is a problem that the inlet and outlet cross-section shapes are fixed and difficult to extend to other cross-section shapes. Summary of the Invention

[0004] The present invention proposes a three-dimensional S-shaped curved concave flow channel design method and system, which can be applied to the computer-aided design of flow channels that transition from various shapes including irregular shapes to circular or elliptical shapes, and can meet the needs of flow channel design with offset inlet and outlet positions.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0006] A method for designing a three-dimensional S-shaped concave flow channel includes the following steps:

[0007] S1. Obtaining the inlet and outlet profiles of a supersonic ramming flow channel;

[0008] S2. Extract N discrete points along the circumference of the inlet profile and the outlet profile respectively to form N pairs of inlet and outlet discrete points;

[0009] S3. Set the variation pattern of the S-curve parameters along the circumference of the runner inlet profile / runner outlet profile, select any set of discrete point pairs, and obtain N S-curves based on the corresponding point coordinates and the S-curve formula;

[0010] S4. Obtain a set of N*M discrete point coordinates on the curve set using M parallel intercepting planes;

[0011] S5. Generate an S-shaped surface from the generated N S-curve envelopes, calculate the area of ​​the two-dimensional cross-sectional figure, and obtain the variation pattern of the flow channel cross-sectional area along the flow direction and the variation pattern of the slope of the center curve of the S-shaped surface;

[0012] S6. Determine whether the change in cross-sectional area of ​​the flow channel along the flow direction and the slope of the center curve are within a reasonable range. If so, the design is completed, the obtained discrete point data file is exported, and imported into the 3D software to create a model. Otherwise, return to step S2 and redesign.

[0013] Furthermore, in step S1, the obtained flow channel inlet profile and flow channel outlet profile are both circular closed lines.

[0014] Furthermore, in step S2, for the symmetrical annular closed line, half of the same side of the runner inlet line and the runner outlet line is used as the selection curve for N discrete points, and the N discrete points are selected sequentially along the selection curve including the end point.

[0015] Furthermore, in step S5, after the N S-curves are generated, the other half of the N S-curves are symmetrically supplemented, and an S-shaped surface is generated by enveloping the 2N S-curves.

[0016] Furthermore, in step S3, the center point of the runner inlet profile is taken as the coordinate origin O, the plane where the runner inlet profile is located is the yz plane, and the direction perpendicular to the yz plane is the x direction, and a coordinate system space O-xyz is established, wherein the projections of the direction in which the runner inlet profile is offset to the runner outlet profile on each coordinate axis are the positive direction of the x-axis, the negative direction of the y-axis, and the positive direction of the z-axis, respectively.

[0017] Furthermore, in step S3, the S-shaped curve formula selected is the cubic Bezier curve formula in the B-spline curve:

[0018] , ;

[0019] Where, represents the coordinates of any point on the S curve, 、 、 and They represent the coordinates of the starting point, inflection point 1, inflection point 2, and end point of the S-curve respectively.

[0020] Furthermore, in step S4, M intercepting planes are set at equal intervals along the x-axis direction to obtain M x-axis coordinates on any S-curve, and then the corresponding parameters are obtained. t The corresponding M y-axis coordinates are obtained by solving the S-shaped curve formula, and the corresponding M z-axis coordinates are obtained by the preset xz coordinate curve to obtain the coordinates of M discrete points.

[0021] Furthermore, in step S5, corresponding to any two-dimensional cross-sectional figure, its area is obtained by the shoelace formula:

[0022] ;

[0023] Where, and The first of the N discrete points of the corresponding two-dimensional cross-sectional graph i The y-axis coordinates and z-axis coordinates of discrete points, and , ;

[0024] Thus, the areas of M two-dimensional cross-sectional figures are obtained.

[0025] Furthermore, the centroid of each two-dimensional cross-sectional figure is obtained by the following formula:

[0026] ;

[0027] Based on the centroids of the M two-dimensional cross-sectional figures obtained, these M discrete points are sequentially connected to construct the center curve of the S-shaped curved surface;

[0028] Formula for finding the slope based on two points:

[0029] ;

[0030] Obtain the centroid position of the y-axis of the center curve of the S-shaped surface at each two-dimensional cross-sectional figure The slope about the x-axis.

[0031] Inverse solution is obtained in this The angle between the cross section of the S-shaped surface and the two-dimensional cross-sectional figure at the position , and then obtain the corresponding cross-sectional area .

[0032] A three-dimensional S-shaped curved concave flow channel design system is also provided, 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.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. The design method proposed in this invention is applicable to various symmetrical inlet and outlet cross-section shapes, such as rectangles, rounded rectangles, circles, ellipses, and some irregular shapes. It can also accommodate flow channels with offset inlet and outlet positions. Therefore, it is applicable to the design of various types of S-bend three-dimensional special-shaped isolation sections, meeting the design requirements of hypersonic vehicles with different aerodynamic layouts.

[0035] 2. The present invention can conveniently adjust the transition curve type of the S-shaped flow channel and the parameters of the S-shaped transition curve at different circumferential positions. By controlling the parameters of the S-shaped transition curve at different circumferential positions, different S-shaped concave flow channel configurations can be obtained under the constraint of fixed inlet and outlet cross-sections. Combined with the guidance of gas dynamics theory, by adjusting the degree of change in the angle of the curve at different circumferential positions (for example, the top curve is slow at first and then fast, or the top curve is fast at first and then slow, with uniform circumferential transition), the circumferential airflow compression process can be adjusted, thereby achieving the effect of optimizing the design of the S-shaped concave flow channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flowchart of the design method of the three-dimensional S-shaped curved concave flow channel of the present invention;

[0037] Figure 2 This is a schematic diagram of the discrete points extracted from the inlet and outlet profiles of the present invention;

[0038] Figure 3 It is a schematic diagram of the changing rules of parameters of multiple S-shaped curves arranged along the axial direction in the present invention;

[0039] Figure 4 is a schematic diagram of an S-shaped curve formed by a set of discrete point pairs in the present invention;

[0040] Figure 5 Schematic diagram of generating N S-curve envelopes to form a three-dimensional S-shaped curved concave flow channel in the present invention;

[0041] Figure 6 Schematic diagram of the centerline of the three-dimensional flow channel, its slope, and the cross-sectional position of the flow channel in the present invention;

[0042] Figure 7 Schematic diagram of the rate of change of the area of ​​the contraction section of the two-dimensional area of ​​the cross-section of the flow channel in the present invention;

[0043] Figure 8Schematic diagram of the curve of the square inlet three-dimensional flow channel designed with the same curve parameters in Example 1;

[0044] Figure 9 3D model diagram of the square inlet 3D flow channel designed with the same curve parameters in Example 1;

[0045] Figure 10 Schematic diagram of the curve of the elliptical inlet three-dimensional flow channel designed with the same curve parameters in Example 2;

[0046] Figure 11 is a three-dimensional model diagram of the elliptical inlet three-dimensional flow channel designed with the same curve parameters in Example 2;

[0047] Figure 12 Schematic diagram of the curve of the elliptical inlet three-dimensional flow channel designed with different curve parameters in Example 3;

[0048] Figure 13 3D model diagram of the elliptical inlet 3D flow channel designed with different curve parameters in Example 3;

[0049] Figure 14 The CFD simulation results of the configuration symmetry plane position in Example 2;

[0050] Figure 15 This is the CFD simulation result of the configuration symmetry plane position in Example 3. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] This invention provides a design method for three-dimensional S-shaped concave flow channels. This method can be applied to the computer-aided design of flow channels transitioning from various shapes, including irregular ones, to circular or elliptical shapes. It can also meet the design requirements of flow channels with offset inlet and outlet positions. The designed flow channel inlet and outlet surfaces are closed. For example, the shape of the flow channel inlet can be set to an irregular quadrilateral, irregular sector, or standard shapes such as rectangle, circle, or ellipse.

[0054] See attached Figure 1A three-dimensional S-shaped curved concave flow channel design method includes the following steps:

[0055] S1. Obtaining a supersonic ramjet flow channel inlet and outlet profiles, wherein the flow channel inlet and outlet profiles form a closed figure, including any regular or irregular shape.

[0056] S2, along the circumference of the inlet and outlet profiles, extract an integer number of N discrete points to form N groups of inlet and outlet discrete point pairs. For the case where both the inlet and outlet profiles are standard regular shapes, such as ellipse, circle, rectangle, regular polygon and other symmetrical shapes. Figure 2 As shown, half of the symmetrical figure with the inlet and outlet lines on the same side is selected as the curve for discrete point selection. N non-overlapping discrete points are sequentially extracted from one end of the curve to the other, and the discrete points include the starting point of the curve. Preferably, the N discrete points are equally divided along the path direction of the curve (with equal length or equal center angle). To facilitate the distinction between points on the inlet and outlet lines, the points on the inlet line are marked as , the points on the outlet profile are marked as .

[0057] S3. Set the variation pattern of the S-curve parameters along the circumference of the runner inlet profile line / runner outlet profile line, select any set of discrete point pairs, and obtain N S-curves based on the corresponding point coordinates and the S-curve formula.

[0058] like Figure 3 and Figure 4 As shown, the center point of the plane area enclosed by the flow channel inlet profile is the coordinate origin O, the plane where the flow channel inlet profile is located is the yz plane, and the direction perpendicular to the yz plane is the x direction. A coordinate system space O-xyz is established, wherein the direction in which the flow channel inlet profile is offset to the flow channel outlet profile is projected on each coordinate axis as the positive direction of the x axis, the negative direction of the y axis, and the positive direction of the z axis. In this way, after the inlet profile and outlet profile are determined, the flow distance L (corresponding to the x-axis direction), the center point height difference H (corresponding to the y-axis direction), and the symmetry plane offset difference D (corresponding to the z-axis direction) between the two profiles are set to determine the inlet profile. The coordinates of each point and the exit profile The coordinates of each point.

[0059] like Figure 3 As shown, according to the four points marked on the inlet profile The four points corresponding to the marked exit lines , respectively, the inlet profile and outlet linear correspondingly divided into three segments. According to the coordinate difference of each discrete point pair, consider the variation law of the S-shaped curve formula parameters along the circumferential direction: for example Discrete point pairs The discrete point pairs can be controlled by parameters to select the spline curve with the type of fast at the beginning and slow at the end. Discrete point pairs The discrete point pairs can use a spline curve of moderate speed, from Discrete point pairs For discrete point pairs, select a spline curve with a slow-in-front and a steep-back curve. In the "sharp-in-front, slow-back" and "slow-in-front, steep-back" scenarios, "front" refers to the section of the S-curve near the inlet profile, "back" refers to the section of the S-curve near the outlet profile, "slow" means the average curvature within the corresponding S-curve segment changes relatively little, and "sharp" means the average curvature within the corresponding S-curve segment changes relatively much.

[0060] Use discrete points to select the discrete point pairs of vertex positions on the curve For example, select an appropriate S-shaped curve formula, such as the Vitor curve formula, the bicubic curve formula, the spline curve formula, etc. Here, the cubic Bezier curve formula in the B-spline curve is selected:

[0061] , ;

[0062] Where, represents the coordinates of any point on the S curve, 、 、 and They represent the coordinates of the starting point, inflection point 1, inflection point 2, and end point of the S-curve respectively.

[0063] like Figure 4 As shown, this type of curve is 、 、 and Four points are used to control its changes, according to the coordinates of the vertices of the import and export points and , which can be determined in the calculation formula and The x-axis coordinate values ​​and y-axis coordinate values ​​corresponding to the two control points are, and Corresponding to the formula and The x-axis coordinate values ​​of the two control points, and Corresponding to the formula and The y-axis coordinate values ​​of the two control points. Adjust the coordinate positions of the two inflection points A and B according to the speed of the curve. and , which can be determined in the calculation formula and The x-axis coordinate values ​​and y-axis coordinate values ​​corresponding to the two inflection points are, and Corresponding to the formula and The x-axis coordinate values ​​of the two control points, and Corresponding to the formula and The y-axis coordinate values ​​of the two control points.

[0064] Considering that the inlet and outlet of the supersonic flow channel are designed to be as horizontal as possible, the y-axis in the formula is kept upward when designing the curve: For the x-axis, according to the properties of the cubic Bezier curve formula and the coordinates of the import and export points, when designing the curve, if the curve needs to be moderate, keep the formula If the curve needs to be fast at the beginning and slow at the end, keep the formula If the curve needs to be slow at the beginning and fast at the end, keep . Once the appropriate curve type is determined, the changing trend of the curve coordinates on the x-axis and y-axis is determined. For the coordinate change of the same S-curve in the z-axis direction, that is, the offset of the z coordinate of the discrete points on the inlet / outlet linear type, can be set as needed, such as the z coordinate and the x coordinate change linearly or nonlinearly. In this embodiment, the z coordinate and the x coordinate change linearly, so that an xz coordinate curve between the two points can be established. In particular, for the two S-shaped curves located on the symmetry plane formed by the two symmetry lines of the inlet linear type and the outlet linear type, the z coordinate values ​​of each point on the curve are the same.

[0065] Repeating the above steps, (N-1) S-shaped curves passing through the remaining (N-1) discrete point pairs can be calculated, for a total of N S-shaped curves. Figure 3 Shown in FIG. 1 are two different types of spline curves constructed by a discrete point pair at the highest point and a discrete point pair at the lowest point.

[0066] S4. Obtain a set of N*M discrete point coordinates on the curve set using M parallel intercepting planes.

[0067] By setting M interception planes parallel to the plane where the inlet line shape / exit line shape is located, M x-axis coordinates on any S curve are obtained, and then the corresponding parameters are obtained. t The corresponding M y-axis coordinates are obtained by solving the S-shaped curve formula, and the corresponding M z-axis coordinates are obtained through the preset xz coordinate curve, and the coordinates of M discrete points are obtained to form a three-dimensional curve containing an array of M points.

[0068] To facilitate subsequent calculations, the M intercepting planes are set at equal intervals along the x-axis, that is, the numerical differences of the x-axis coordinates of the M discrete points intercepted are the same. In this embodiment, the z-coordinate changes linearly with the x-coordinate, so the numerical differences of the z-axis coordinates of the M discrete points intercepted are also the same.

[0069] S5. Generate an S-shaped surface by enveloping the N generated S-curves, calculate the area of ​​the two-dimensional cross-sectional figure, and obtain the variation law of the flow channel cross-sectional area along the flow direction and the variation law of the slope of the center curve of the S-shaped surface.

[0070] Since in the previous step, half of the symmetrical figure with the inlet and outlet lines on the same side is selected as the curve for discrete point selection, the N S-curves obtained above can be automatically supplemented with the N S-curves on the other side of the symmetry plane after being symmetrically mirrored by the symmetry plane. In this way, a three-dimensional figure can be generated by the envelope of the 2N curves, as shown in FIG. Figure 5 When the inlet profile or outlet profile is asymmetrical, since the N discrete point pairs are selected along the entire closed loop of the inlet profile or outlet profile, the N S-shaped curves formed by the above process can be directly enveloping to generate an S-shaped surface.

[0071] Similarly, the M intercepting planes in step S4 are selected to divide the S-shaped curved surface generated by the envelope into M two-dimensional cross-sectional figures at equal intervals, such as Figure 6 As shown in the figure, the dotted closed loop graph corresponds to the x-axis coordinate selected as The intersection line of a cutting plane and the S-shaped surface at this time is the dotted closed loop figure, which is one of the two-dimensional cross-sectional figures obtained by dividing the S-shaped surface by the cutting plane. The centroid of each two-dimensional cross-sectional figure is obtained by the following formula:

[0072] ;

[0073] Based on the centroids of the M two-dimensional cross-sectional figures obtained, these M discrete points are connected in sequence to construct the central curve of the S-shaped surface.

[0074] According to the derivation formula:

[0075] ;

[0076] Find the centroid position of the y-axis in each two-dimensional cross-section figure Slope about the x-axis .

[0077] For symmetrical figures, the z coordinate of the centroid of each two-dimensional interface figure is a constant, so the z coordinate of the three-dimensional center line formed is fixed, and the three-dimensional center line can be projected onto the two-dimensional curve in the xy plane for calculation.

[0078] Centroid position of a two-dimensional cross-section figure And the slope is The straight line is used as the normal line to create M cross-sectional planes, which can correspondingly separate the S-shaped surface into M two-dimensional cross-sectional sections. Figure 6 As shown, the solid closed loop graph in the figure corresponds to the x-axis coordinate selected as The intersection line of a transverse cutting plane and the S-shaped curved surface is a solid closed loop figure, which is one of the two-dimensional cross-sectional figures obtained by separating the S-shaped curved surface by the transverse cutting plane.

[0079] For any two-dimensional cross-sectional shape, its area is obtained by the shoelace formula:

[0080] , ;

[0081] Where, and The first of the N discrete points of the corresponding two-dimensional cross-sectional graph i The y-axis coordinates and z-axis coordinates of discrete points, and , . Thus, the areas of M two-dimensional cross-sectional figures are obtained.

[0082] Find the centroid position of the y-axis in each two-dimensional cross-section figure Slope about the x-axis Afterwards, according to Figure 6 The geometric relationship between the figures shown in the figure can be solved by reverse analysis. The angle between the cross section of the S-shaped surface and the two-dimensional cross-sectional figure at the position , and then estimate the corresponding cross-sectional area .

[0083] S6. Determine whether the change in cross-sectional area of ​​the flow channel along the flow direction and the slope of the center curve are within a reasonable range. If so, the design is completed, the obtained discrete point data file is exported, and imported into the 3D software to create a model. Otherwise, return to step S2 and redesign.

[0084] After calculating and obtaining M cross-sectional areas in step S5, it is possible to determine whether the cross-sectional area change trend of the channel is within a reasonable range based on the change in the cross-sectional area, and whether the cross-sectional area change trend of the channel is within a reasonable range. Figure 7 Whether the change in the area of ​​the contraction section shown meets the requirements can be used to determine whether the curve design is reasonable.

[0085] If the change in cross-sectional area meets the relevant requirements, the design can be considered complete. At this point, the obtained discrete point coordinate data is saved and exported in a preset format file. Furthermore, the obtained discrete point coordinates can be imported into 3D software to generate a 3D flow channel surface. If the change in cross-sectional area does not meet the relevant requirements, refer to the previously calculated parameters and re-enter step S2 to reselect a more appropriate curve type and parameters. Then, repeat the subsequent steps to regenerate the S-shaped curve and generate the S-shaped surface through the S-shaped curve envelope.

[0086] Example 1:

[0087] In this embodiment, the flow channel has a square inlet and a circular outlet with an offset in the inlet and outlet cross-section centers. The square side length of the inlet cross-section is 106.4 mm, and the radius of the circular outlet cross-section is 60 mm. The flow distance between the inlet and outlet cross-sections is 1400 mm, and the center point height difference is 140 mm. In this design case, the inlet and outlet cross-section curves are divided into 402 pairs of discrete points. The transition curve type of the discrete point pairs is a B-spline curve, and the formula parameters of this curve are: , .

[0088] According to the coordinates of the discrete points at the import and export locations, determine the and The value of , combined with the curve's urgency, adjusts the coordinate points A and B to determine the formula and In this embodiment, set , The number of coordinates on the x-axis is determined to be 1401, and the numerical difference of the distribution is the same, that is, a coordinate point is set every 1mm in the x-axis direction. The corresponding coordinate points on the x-axis are used to find the corresponding t After determining the value of the parameter, we can then find the y-axis coordinate point value corresponding to the x-axis coordinate point. The z-coordinate and x-coordinate of the import and export discrete points change linearly.

[0089] Figure 8 This figure shows the curves that form the flow channel envelope during the design process. It should be noted that for clarity, only a portion of the curves are shown. Figure 9 This is the three-dimensional model diagram of the designed flow channel surface.

[0090] Example 2:

[0091] In this embodiment, the flow channel has an elliptical inlet and a circular outlet, with the inlet and outlet cross-sections offset from each other. The semi-major axis of the inlet cross-section ellipse is 90 mm, the semi-minor axis is 40 mm, and the radius of the outlet cross-section is 60 mm. The flow distance between the inlet and outlet cross-sections is 1400 mm, and the height difference between the center points is 140 mm. In this design example, the inlet and outlet cross-section curves are divided into 402 pairs of discrete points, and the transition curve type for these discrete point pairs is the same B-spline curve as above.

[0092] According to the coordinates of the discrete points at the import and export locations, determine the and The value of , combined with the curve's urgency, adjusts the coordinate points A and B to determine the formula and In this embodiment, set , Similarly, the number of coordinates in the x-axis direction is determined to be 1401, and the numerical difference of the distribution is the same, that is, a coordinate point is set every 1mm in the x-axis direction. The corresponding coordinate points on the x-axis are used to find the corresponding t After determining the value of the parameter, we can then find the y-axis coordinate point value corresponding to the x-axis coordinate point. The z-coordinate and x-coordinate of the import and export discrete points change linearly.

[0093] Figure 10 This figure shows the curves that form the flow channel envelope during the design process. It should be noted that for clarity, only a portion of the curves are shown. Figure 11 This is the three-dimensional model diagram of the designed flow channel surface.

[0094] Example 3:

[0095] In this embodiment, the flow channel has an elliptical inlet and a circular outlet, with the inlet and outlet cross-sections offset from each other. The semi-major axis of the inlet cross-section ellipse is 90 mm, the semi-minor axis is 40 mm, and the radius of the circular outlet cross-section is 60 mm. The flow distance between the inlet and outlet cross-sections is 1400 mm, and the height difference between the center points is 140 mm. Similarly, in this design case, the inlet and outlet cross-section curves are divided into 402 pairs of discrete points, and the transition curve type for these discrete point pairs is the same B-spline curve as above.

[0096] According to the coordinates of the discrete points at the import and export locations, determine the and The value of , combined with the curve's urgency, adjusts the coordinate points A and B to determine the formula and In this embodiment, set , and in the x-axis direction, and The value of is adjusted in clockwise direction. Specifically: there are 201 pairs of discrete points on the right side of the discrete point, and the value is set at the vertex. , .for , from point At the beginning, each time a point is passed, the corresponding parameter value decreases by 1; , each time a point is reached, the corresponding parameter value increases by 1 until the endpoint is reached At this time , Similarly, the number of coordinates in the x-axis direction is determined to be 1401, and the numerical difference of the distribution is the same, that is, a coordinate point is set every 1mm in the x-axis direction. The corresponding coordinate points on the x-axis are used to find the corresponding t After determining the value of the parameter, we can then find the y-axis coordinate point value corresponding to the x-axis coordinate point. The z-coordinate and x-coordinate of the import and export discrete points change linearly, thus completing the setting of the curve parameters.

[0097] Figure 12 This figure shows the curves that form the flow channel envelope during the design process. It should be noted that for clarity, only a portion of the curves are shown. Figure 13 This is the three-dimensional model diagram of the designed flow channel surface.

[0098] Figure 14 and Figure 15 The CFD simulation results of the positions of the symmetric planes of the configurations in Example 2 and Example 3 are shown respectively. Under the same conditions of an inlet flow of 2 Mach, a static pressure of 12494 Pa, and an outlet static pressure of 3 times the inlet flow, the position of the symmetric surface shock wave train in Example 3 is closer to the downstream. In addition, the experimental data in the table below also show that the total pressure recovery coefficient of the outlet section of the configuration in Example 3 is higher than that of the configuration in Example 2. This shows that the flow channel designed in Example 3 has higher performance, and also reflects the advantage of this method, that is, the optimized design of the flow channel can be achieved by adjusting the circumferential curve parameters.

[0099]

[0100] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A three-dimensional S-shaped curved concave flow channel design method, characterized in that: The following steps are involved: S1. Obtaining the inlet and outlet profiles of a supersonic ramming flow channel; S2. Extract N discrete points along the circumference of the inlet profile and the outlet profile respectively to form N pairs of inlet and outlet discrete points; S3. Set the variation pattern of the S-curve parameters along the circumference of the runner inlet profile / runner outlet profile, select any set of discrete point pairs, and obtain N S-curves based on the corresponding point coordinates and the S-curve formula; S4. Obtain a set of N*M discrete point coordinates on the curve set using M parallel intercepting planes; S5. Generate an S-shaped surface from the generated N S-curve envelopes, calculate the area of ​​the two-dimensional cross-sectional figure, and obtain the variation pattern of the flow channel cross-sectional area along the flow direction and the variation pattern of the slope of the center curve of the S-shaped surface; S6. Determine whether the change in cross-sectional area of ​​the flow channel along the flow direction and the slope of the center curve are within a reasonable range. If so, the design is completed, the obtained discrete point data file is exported, and imported into the 3D software to create a model. Otherwise, return to step S2 and redesign.

2. The method for designing a three-dimensional S-shaped concave flow channel according to claim 1, characterized in that: In step S1 , the obtained flow channel inlet profile and flow channel outlet profile are both circular closed lines.

3. The method for designing a three-dimensional S-shaped concave flow channel according to claim 2, wherein: In step S2, for a symmetrical annular closed line, half of the same side of the runner inlet line and the runner outlet line is used as a selection curve for N discrete points, and the N discrete points are selected sequentially along the selection curve including the end point.

4. The method for designing a three-dimensional S-shaped concave flow channel according to claim 3, wherein: In step S5, after the N S-curves are generated, the other half of the N S-curves are symmetrically supplemented, and an S-shaped surface is generated by enveloping the 2N S-curves.

5. The method for designing a three-dimensional S-shaped concave flow channel according to any one of claims 1 to 4, characterized in that: In step S3, the center point of the runner inlet profile is taken as the coordinate origin O, the plane where the runner inlet profile is located is the yz plane, and the direction perpendicular to the yz plane is the x direction. A coordinate system space O-xyz is established, wherein the projections of the direction in which the runner inlet profile is offset to the runner outlet profile on each coordinate axis are the positive direction of the x-axis, the negative direction of the y-axis, and the positive direction of the z-axis respectively.

6. The method for designing a three-dimensional S-shaped concave flow channel according to claim 5, characterized in that: In step S3, the S-shaped curve formula selected is the cubic Bezier curve formula in the B-spline curve: ， ； Where, represents the coordinates of any point on the S curve, 、 、 and They represent the coordinates of the starting point, inflection point 1, inflection point 2, and end point of the S-curve respectively.

7. The method for designing a three-dimensional S-shaped concave flow channel according to claim 6, wherein: In step S4, M intercepting planes are set at equal intervals along the x-axis direction to obtain M x-axis coordinates on any S-curve, and then the corresponding parameters are obtained. t The corresponding M y-axis coordinates are obtained by solving the S-shaped curve formula, and the corresponding M z-axis coordinates are obtained by the preset xz coordinate curve to obtain the coordinates of M discrete points.

8. The method for designing a three-dimensional S-shaped concave flow channel according to claim 7, wherein: In step S5, corresponding to any two-dimensional cross-sectional figure, its area is obtained by the shoelace formula: ； Where, and The first of the N discrete points of the corresponding two-dimensional cross-sectional graph i The y-axis coordinates and z-axis coordinates of discrete points, and , ; Thus, the areas of M two-dimensional cross-sectional figures are obtained.

9. A three-dimensional S-shaped concave flow channel design system, 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 8 are implemented.

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