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CN-121997817-A - Full three-dimensional air inlet space wall surface pressure distribution reverse design feature construction method

CN121997817ACN 121997817 ACN121997817 ACN 121997817ACN-121997817-A

Abstract

The invention provides a method for constructing a three-dimensional wall surface pressure distribution reverse design characteristic of a full three-dimensional air inlet channel, which comprises the following steps of (1) providing a circumferential change rule of a pressure curve control point according to a circumferential angle of a shock wave dependence region end point, (2) providing a p-x curve of a pseudo flow direction based on spline curves and defining that theta values of each curve are the same in a p-x-theta coordinate system, (3) carrying out parameter distribution on each p-x curve of the pseudo flow direction, reversely solving control points of a spline mixing function with low frequency, and obtaining a mixing function of each pressure curve of the pseudo flow direction, (4) constructing a three-dimensional pressure curve interpolated on the pressure curve according to a parameter equation of the pressure curve. The invention can improve the construction efficiency and flexibility of the space wall surface pressure distribution reverse design characteristic of the full three-dimensional air inlet reverse design method.

Inventors

  • LIU RUI
  • JIN ZHIGUANG

Assignees

  • 南京航空航天大学

Dates

Publication Date
20260508
Application Date
20260112

Claims (10)

  1. 1. A method for constructing a full three-dimensional air inlet three-dimensional wall surface pressure distribution reverse design feature is characterized by comprising the following steps: (1) According to the circumferential angle of the end point of the shock wave dependent region, a circumferential change rule of a pressure curve control point is given; (2) Giving a p-x curve of a pseudo flow direction based on a spline curve, and defining that theta values of each curve are the same in a p-x-theta coordinate system, wherein p is the pressure, x is the flow direction position, and theta is the circumferential angle of the end point of a corresponding dependent region of the pressure curve; (3) Parameter distribution is carried out on each p-x curve of the pseudo flow direction, control points of spline mixing functions with low times are reversely solved, and a mixing function of each pseudo flow direction pressure curve is obtained; (4) And constructing and obtaining the three-dimensional pressure curved surface interpolated on the pressure curve according to the parameter equation of the pressure curved surface.
  2. 2. The method according to claim 1, wherein the step (1) specifically comprises: (1.1) determining an axial point of a circumferential angle of the ending point as an intersection point of a symmetrical plane and a lip profile, wherein the circumferential angle is formed by the connecting line of the ending point and the axial point and a y axis; (1.2) giving the change rule of the coordinates of the pressure curve control points along with the angle by using a spline rule; (1.3) coordinates of the control point of each curve are determined according to the circumferential angle of the corresponding end point.
  3. 3. The method of claim 2, wherein in the step (1.2), the circumferential change rule of the pressure curve control points is set according to the top plate and the side plate of the air intake duct, respectively.
  4. 4. The method of claim 1, wherein in step (2), the first control point of each "pseudo-flow direction" p-x curve is defined as the end point of the shock-dependent region, and the second control point is positioned so as to satisfy the slope of the line connecting the second control point and the first control point, and is consistent with the flow direction pressure gradient at the end point.
  5. 5. The method according to claim 1, wherein said step (3) of inverse-solving the control points of the spline mixing function of a low number of times comprises the steps of: (3.1) performing parameter distribution on each pressure curve to obtain a parameter vector ; (3.2) Constructing the mixing function with low-order B-splines Wherein the distribution value of the pressure curve parameter needing interpolation maintains the original data Unchanged; (3.3) determining a node vector of the B-spline mixing function to be solved; (3.4) solving a B spline basis function according to the node vector; and (3.5) substituting the parameter points to be interpolated into a B spline parameter equation, and solving a linear equation set to obtain control points of the B spline mixing function by inverse solution.
  6. 6. The method of claim 5, wherein in the step (3.1), the parameter distribution is performed on each pressure curve in a uniform distribution manner within a range of 0-1.
  7. 7. The method of claim 5, wherein in the step (3.2), the mixing function is a function of Adopting a low-order B-spline structure to avoid oscillation, and meeting the following formula: Wherein, the For the numbering of the pressure curve corresponding to the mixing function, The value of (2) is the total number of pressure curves minus one, Assigning vectors to parameters I-th element of (a) in the list.
  8. 8. The method of claim 5, wherein in the step (3.3), the node vector U of the B-spline blending function is determined by the following formula: Wherein, the For the number of pressure curves, For the number of times of the B-spline curve, For the i +1 element in the node vector U, Assigning vectors to parameters I-th element of (a) in the list.
  9. 9. The method according to claim 1, wherein the step (4) specifically comprises: (4.1) defining each pressure curve as an isoparametric line of the pressure curve, wherein the parameter value is an allocated parameter; (4.2) constructing a three-dimensional pressure curved surface according to a parameter equation of the pressure curved surface, wherein the parameter expression of the three-dimensional pressure curved surface is as follows: Wherein, the For the numbering of the pressure curve corresponding to the mixing function, Is the first The parametric expression of the pressure curve, 、 As an argument of the parametric expression, The value of (2) is the total number of pressure curves minus one.
  10. 10. The three-dimensional pressure curved surface for the reverse design of the full three-dimensional air inlet channel is characterized in that the pressure curved surface is constructed by the method for constructing the reverse design characteristics of the pressure distribution of the three-dimensional wall surface of the full three-dimensional air inlet channel according to any one of claims 1 to 9; The pressure curved surface is expressed by parameters Definition, wherein, Is the first The parametric expression of the pressure curve, Is the first to The pressure curves correspond to a mixing function based on a low-order B-spline construction, and the pressure surfaces are interpolated over a given set of spatial pressure curves.

Description

Full three-dimensional air inlet space wall surface pressure distribution reverse design feature construction method Technical Field The invention belongs to the technical field of aerospace, and particularly relates to a method for constructing reverse design characteristics of wall surface pressure distribution of a full three-dimensional air inlet space. Background The existing mature design concept of the inner rotating air inlet mainly adopts a reference flow field and streamline tracking to design the air inlet profile, the air inlet can also keep the flow characteristics of the reference flow field to a certain extent, the conventional design method of the inner rotating air inlet can only directly specify the wall pressure distribution of the reference flow field, and the wall pressure distribution of the air inlet obtained by streamline tracking is deviated from a preset input condition. And the shock wave shape of the air inlet is still limited to axisymmetric/non-axisymmetric inner conical curved surfaces, and the air inlet reverse design aiming at the reverse design target in a general sense cannot be completed by the traditional method. In order to further expand the design freedom degree of the three-dimensional inward-rotation air inlet, a novel multi-feature and controllable full-three-dimensional curved surface compression air inlet concept (Gneralized three-dimensional inlet, G3D inlet) is provided, the flow field and the compression surface of the full-three-dimensional air inlet are not dependent on any translational symmetry or rotational symmetry any more, the novel full-three-dimensional air inlet has general three-dimensional characteristics, wherein the characteristic line method (SMOC) based on a spatial streamline can carry out the inverse design of an air inlet profile based on general three-dimensional inverse design characteristics, the three-dimensional wall pressure distribution is obtained by not solving three-dimensional coordinates of the wall surface of a main compression area of the air inlet, therefore, given bulge three-dimensional wall pressure distribution in "Stream-Surface Iteration-Based Flowfield Calculation Method for Pressure-Controllable Waverider Design" paper published by sun and the like can only be limited to be given in a mode of plane projection, the wall pressure distribution given in the three-dimensional inward-rotation air inlet design considering cruise attack angle published by Zheng Xiaogang and the like is limited to be given in a local virtual plane according to a pressure curve, the starting point of the three-dimensional wall pressure distribution related to the text is an ending point of a front edge wave dependent area, the spatial distribution flow direction and the circumferential span is large, and the following main compression area is not solved, and the pressure distribution in a radial plane cannot be directly configured to a two-dimensional space pressure distribution is required to be given by a proper method. Disclosure of Invention In view of the lack of an effective, flexible and physically realizable parameterized definition method for spatial wall pressure distribution in the reverse design of an all-three-dimensional air inlet channel in the prior art, particularly, the problem that a three-dimensional pressure distribution characteristic which is smoothly connected with an upstream shock wave dependent region and is controllable in both the flow direction and the circumferential direction cannot be directly constructed is solved. Specifically, the invention provides a construction method of a three-dimensional wall pressure distribution reverse design feature, which aims to overcome the defect that pressure distribution assignment in the traditional method is limited by two-dimensional plane projection or local flow surface and cannot adapt to large-span three-dimensional space distribution. In order to achieve the above purpose, the invention adopts the following technical scheme: a method for constructing a full three-dimensional air inlet three-dimensional wall pressure distribution reverse design feature comprises the following steps: (1) According to the circumferential angle of the end point of the shock wave dependent region, a circumferential change rule of a pressure curve control point is given; (2) Giving a p-x curve of a pseudo flow direction based on a spline curve, and defining that theta values of each curve are the same in a p-x-theta coordinate system, wherein p is the pressure, x is the flow direction position, and theta is the circumferential angle of the end point of a corresponding dependent region of the pressure curve; (3) Parameter distribution is carried out on each p-x curve of the pseudo flow direction, control points of spline mixing functions with low times are reversely solved, and a mixing function of each pseudo flow direction pressure curve is obtained; (4) And constructing and obtaining the t