Elastic deformation structure grid generation method for revolution body model

Abstract

The invention provides an elastic deformation structure grid generation method for a revolution body model, and the method comprises the steps: constructing a structure grid of a rigid body model, and obtaining the three-dimensional coordinates of grid points in the structure grid of the rigid body model; according to the axial position and the normal deformation amount of the central axis of the elastic deformation model, fitting to obtain a high-order spline curve equation most conforming to the contour of the central axis; constructing a three-dimensional coordinate mapping relation between grid point coordinates of the rigid body model and grid point coordinates of the elastic deformation model according to a high-order spline curve equation of the central axis contour; and performing coordinate transformation on the rigid body model grid points according to the three-dimensional coordinate mapping relation, determining three-dimensional coordinates of the elastic deformation model grid points, and obtaining a grid structure of the elastic deformation model. The method can be suitable for program generation of the structural grid of the elastic model when the spline curve equation of the axis of the revolution body appearance is known, manual grid generation is not needed, and the efficiency can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of computational fluid dynamics (CFD), and in particular relates to a method for generating an elastic deformation structure grid for a rotational body model. Background Art

[0002] Reaction Control System (RCS) is a direct force control system that uses the engine jet to generate reaction force to quickly change the motion attitude or trajectory of the aircraft. Its role is to supplement the inefficiency of aerodynamic control surfaces and quickly change the flight state. It has broad prospects for engineering applications. When the RCS jet enters the super / hypersonic outflow, it will interact with each other to form a complex shock wave / boundary layer interference flow field containing various flow phenomena such as boundary layer separation and reattachment, shock waves, expansion waves, Mach disks, shear layers, etc., and produce aerodynamic / thermal interference that varies strongly nonlinearly with jet parameters, flight conditions, layout forms, etc.

[0003] Numerical grid generation technology is a discipline that emerged with the development of CFD. Grids can generally be divided into three categories, namely rectangular grids, structured grids, and unstructured grids. In engineering applications, it is required to simulate this complex interference flow field as accurately as possible, and extract the aerodynamic / thermal changes caused by the interference as input for control system design to ensure design accuracy. Therefore, structured grids are generally used to simulate jet interference flow fields. Structured grids are body-fitting and can accurately and efficiently simulate boundary layers, discontinuities, etc., with high calculation accuracy. However, structured grids have poor adaptability to complex geometric configurations, and grid generation is difficult and time-consuming, which greatly limits the calculation efficiency.

[0004] For a high slenderness ratio rotational body model, elastic deformation will occur under the action of high dynamic pressure / high static pressure / high angle of attack of the external flow. This deformation will cause the aerodynamic load on the model surface to change, affecting the accurate estimation of aerodynamic force. This elastic deformation changes with the external flow parameters. Traditional grid generation methods require a lot of manpower and time to perform one by one, which is difficult to meet engineering needs. Therefore, it is urgent to establish a structural grid based on an inelastic rigid body model and a processing method for quickly generating elastic deformation structural grids of high-order spline curves with a given central axis profile. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the inventors have conducted intensive research and provided a method for generating elastic deformation structural meshes for rotational body models. Taking the structural mesh of the original rigid body model as a benchmark, the method realizes the generation of elastic deformation structural meshes of high-order spline curves with a given central axis profile through coordinate transformation, thereby ensuring the consistency of mesh quality, mesh quantity and mesh topology before and after the conversion to the greatest extent, which can greatly save the time of manual mesh generation.

[0006] The technical solution provided by the present invention is as follows:

[0007] In a first aspect, a method for generating an elastic deformation structure mesh for a rotational body model comprises:

[0008] Constructing a structural grid of the rigid body model, and obtaining three-dimensional coordinates of grid points in the structural grid of the rigid body model;

[0009] A three-dimensional coordinate system is established, the central axis direction of the elastic deformation model is set as the X-axis, the normal direction is set as the Y-axis, the elastic deformation model is deformed along the Y-axis, and the Z-axis is determined according to the right-hand rule;

[0010] According to the axial position and normal deformation of the central axis of the elastic deformation model, a high-order polynomial is used to approximate the central axis, fit the central axis, determine the highest power and independent variable coefficient of the high-order spline curve equation, and obtain the high-order spline curve equation that best fits the contour of the central axis;

[0011] According to the high-order spline curve equation of the central axis contour, a three-dimensional coordinate mapping relationship between the grid point coordinates of the rigid model and the grid point coordinates of the elastic deformation model is constructed to satisfy the unchanged axial coordinates, the normal coordinates are converted according to the high-order spline curve equation of the central axis, and the Z-axis coordinates remain unchanged;

[0012] The grid points of the rigid body model are transformed according to the three-dimensional coordinate mapping relationship, the three-dimensional coordinates of the grid points of the elastic deformation model are determined, and the grid structure of the elastic deformation model is obtained.

[0013] In a second aspect, a device for generating an elastic deformation structure grid for a rotational body model comprises:

[0014] one or more processors;

[0015] a storage device for storing one or more programs,

[0016] When the one or more programs are executed by the one or more processors, the one or more processors implement the elastic deformation structure mesh generation method for a rotational body model described in the first aspect.

[0017] In a third aspect, a readable storage medium stores a computer program, which, when executed by a processor, implements the elastic deformation structure mesh generation method for a rotational body model described in the first aspect.

[0018] In a fourth aspect, a computer program product is provided, comprising: a computer program (also referred to as code, or instruction), which, when executed, executes the elastic deformation structural mesh generation method for a rotational body model described in the first aspect.

[0019] The elastic deformation structure grid generation method for a rotational body model provided by the present invention has the following beneficial effects:

[0020] (1) The present invention provides a method for generating an elastic deformation structural grid for a rotational body model. Based on the normal deformation amount of the central axis of the rotational body model and the high-order spline curve equation of the axial position, a mapping relationship between the coordinates of the structural grid points of the inelastic rigid body model and the coordinates of the structural grid points of the elastic deformation model is established, so as to realize the generation of the structural grid of the elastic deformation model from the original inelastic model structural grid to the given central axis curve. The method is suitable for programmatic generation of the structural grid of the elastic model when the spline curve equation of the central axis of the rotational body shape is known, without the need for manual grid generation, which can greatly improve efficiency.

[0021] (2) The present invention provides a method for generating a mesh of an elastic deformation structure for a rotational body model. It only needs to give a spline curve equation of the central axis and adjust the coefficients and degrees of the high-order spline curve equation to make it fit the geometric contour of the central axis as closely as possible. This can realize the generation of mesh of the elastic deformation model under different flight parameters (Mach number, altitude, angle of attack). The method has a fast processing speed and is relatively simple to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the grid conversion method;

[0023] Figure 2 It is a schematic diagram of the original rigid body model mesh and the elastic deformation model mesh after conversion;

[0024] Figure 3 Schematic diagram of numerical simulation flow field results. DETAILED DESCRIPTION

[0025] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0026] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0027] The present invention provides a method for generating elastic deformation structure grids for a rotational body model, such as Figure 1 As shown, the following steps are included:

[0028] (1) Construct a structural grid of a rigid body digital model (referred to as model) as a benchmark, and obtain the three-dimensional coordinates of the grid points in the structural grid of the rigid body model.

[0029] (2) Establish a three-dimensional coordinate system, set the central axis direction of the elastic deformation model as the X-axis, set the model head to tail as the positive direction, and record the axial position as x; set the normal (vertical) direction as the Y-axis, set the vertical upward direction as the positive direction, the elastic deformation model deforms along the Y-axis, and the normal deformation is recorded as y; determine the Z-axis according to the right-hand rule, and record the position on the Z-axis as z; then the central axis of the original rigid body model satisfies y=0, z=0; the central axis of the elastic deformation model satisfies y=f(x), z=0.

[0030] (3) Based on the axial position x and normal deformation y of the central axis of the elastic deformation model, a high-order polynomial is used to approximate the central axis at this time, and the high-order spline curve equation that best fits the contour of the central axis is obtained. The highest power n and independent variable coefficients A~N of the curve are determined. The format is as follows:

[0031] f(x)=A+B·x+…+N·x n , n≤6

[0032] (4) Establish a three-dimensional coordinate mapping between the grid point coordinates of the inelastic rigid body model and the grid point coordinates of the elastic deformation model. The mapping relationship satisfies that the X-axis (axial) coordinate remains unchanged, the Y-axis (normal) coordinate is converted according to the spline curve of the central axis of the deformed model, and the Z-axis (lateral) coordinate remains unchanged.

[0033] For the part of the grid point whose axial (X-axis) coordinates are within the model range, the normal (Y-axis) grid point is transformed based on the normal deformation of the model, and the axial (X-axis) and lateral (Z-axis) coordinates remain unchanged. The three-dimensional coordinates of the grid points before and after the transformation satisfy the following mapping relationship:

[0034] x 弹性 =x 刚体

[0035] y 弹性 =y 刚体 +f(x)

[0036] z 弹性 =z 刚体

[0037] For the part where the axial (X-axis) coordinates of the grid points exceed the model range, the normal (Y-axis) grid points are transformed based on the normal deformation of the model end point, and the axial (X-axis) and lateral (Z-axis) coordinates remain unchanged. The three-dimensional coordinates of the grid points before and after the transformation satisfy the following mapping relationship:

[0038] x 弹性 =x 刚体

[0039] y 弹性 =y 刚体 +f(x 末端点 )

[0040] z 弹性 =z 刚体

[0041] (5) The grid points of the rigid body model are transformed according to the three-dimensional coordinate mapping relationship, the three-dimensional coordinates of the grid points of the elastic deformation model are determined, and the grid structure of the elastic deformation model is obtained.

[0042] The present invention conducts a grid generation method test on a rotational body model, the axial length of the model is 5450mm, Figure 2 The grid schematic diagrams before and after the conversion are compared. The converted grid retains the geometric topology of the original grid, the grid volume remains unchanged, and the grid has no negative volume. In order to verify the reliability of the grid generation method, numerical simulation tests are carried out on the grids before and after the conversion. The incoming flow Mach number is given as 4, the incoming flow static pressure is 5529.31Pa, the incoming flow static temperature is 216.65K, and the angle of attack is 0°. Both grids can obtain flow field calculation results that conform to the rules, such as Figure 3 As shown, the effectiveness of the present invention in calculating the jet interference flow field is verified.

[0043] The present invention also provides a device for generating an elastic deformation structure grid for a rotational body model, comprising:

[0044] one or more processors;

[0045] A storage device for storing one or more programs;

[0046] When the one or more programs are executed by the one or more processors, the one or more processors implement the elastic deformation structure mesh generation method for a rotational body model described in the first aspect.

[0047] The present invention also provides a readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the elastic deformation structure grid generation method for a rotational body model described in the first aspect.

[0048] The readable storage medium includes, but is not limited to, various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0049] The present invention also provides a computer program product, which includes: a computer program (also referred to as code, or instruction), which, when executed, executes the elastic deformation structural grid generation method for a rotational body model described in the first aspect.

[0050] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, microwave, etc.) mode to another website site, computer, server or data center.

[0051] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0052] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0053] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0054] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for generating elastic deformation structure grid for a rotational body model, characterized in that: include: Constructing a structural grid of the rigid body model, and obtaining three-dimensional coordinates of grid points in the structural grid of the rigid body model; A three-dimensional coordinate system is established, the central axis direction of the elastic deformation model is set as the X-axis, the normal direction is set as the Y-axis, the elastic deformation model is deformed along the Y-axis, and the Z-axis is determined according to the right-hand rule; According to the axial position and normal deformation of the central axis of the elastic deformation model, a high-order polynomial is used to approximate the central axis, fit the central axis, determine the highest power and independent variable coefficient of the high-order spline curve equation, and obtain the high-order spline curve equation that best fits the contour of the central axis; According to the high-order spline curve equation of the central axis contour, a three-dimensional coordinate mapping relationship between the grid point coordinates of the rigid model and the grid point coordinates of the elastic deformation model is constructed to satisfy the unchanged axial coordinates, the normal coordinates are converted according to the high-order spline curve equation of the central axis, and the Z-axis coordinates remain unchanged; The grid points of the rigid body model are transformed according to the three-dimensional coordinate mapping relationship, the three-dimensional coordinates of the grid points of the elastic deformation model are determined, and the grid structure of the elastic deformation model is obtained.

2. The method for generating elastic deformation structure grid for rotational body model according to claim 1, characterized in that: The high-order spline curve equation is: f(x)=A+B·x+…+N·x n , n≤6; Where x is the axial position of the central axis, and y is the normal deformation of the central axis.

3. The method for generating elastic deformation structure grid for rotational body model according to claim 1, characterized in that: The step of transforming the grid points of the rigid body model according to the three-dimensional coordinate mapping relationship includes: for the part where the axial position of the grid points is within the model range, the normal grid points are transformed based on the normal deformation of the model, and the axial and lateral directions remain unchanged. The three-dimensional coordinates of the grid points before and after the transformation satisfy the following mapping relationship: x 弹性 =x 刚体 y 弹性 =y 刚体 +f(x) With 弹性 =from 刚体 Among them, x 刚体 、x 弹性 are the axial coordinates of the grid points of the structural grid of the rigid body model and the elastic deformation model, respectively. 刚体 ,y 弹性 are the normal coordinates of the grid points of the structural mesh of the rigid body model and the elastic deformation model, respectively, 刚体 、z 弹性 The lateral coordinates of the grid points of the structural mesh for the rigid body model and the elastic deformation model, respectively.

4. The method for generating elastic deformation structure grid for rotational body model according to claim 1, characterized in that: The step of transforming the grid points of the rigid body model according to the three-dimensional coordinate mapping relationship includes: for the part of the grid points that exceeds the model range in the axial direction, the normal grid points are transformed based on the normal deformation of the end point of the model, and the axial and lateral directions remain unchanged. The three-dimensional coordinates of the grid points before and after the transformation satisfy the following mapping relationship: x 弹性 =x 刚体 y 弹性 =y 刚体 +f(x 末端点 ) With 弹性 =from 刚体 Among them, x 刚体 、x 弹性 are the axial coordinates of the grid points of the structural grid of the rigid body model and the elastic deformation model, respectively. 刚体 ,y 弹性 are the normal coordinates of the grid points of the structural mesh of the rigid body model and the elastic deformation model, respectively, 刚体 、z 弹性 The lateral coordinates of the grid points of the structural mesh for the rigid body model and the elastic deformation model, respectively.

5. A device for generating elastic deformation structure grids for a rotational body model, characterized in that: include: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the elastic deformation structure mesh generation method for a rotational body model as described in any one of claims 1 to 4.

6. A readable storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the method for generating an elastic deformation structure grid for a rotational body model as claimed in any one of claims 1 to 4 is implemented.

7. A computer program product, characterized in that The computer program product comprises: a computer program, which, when being executed, executes the elastic deformation structure mesh generation method for a rotational body model according to any one of claims 1 to 4.

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