Method for obtaining boundary conditions of opening walls for CFD calculations in transonic wind tunnels

Abstract

The present invention discloses a method for obtaining aperture wall boundary conditions for transonic wind tunnel CFD calculations. The method receives input set wind tunnel parameters and receives CFD calculation states extracted from a flow field; calls a set aperture wall mass flow flux calculation function based on the received wind tunnel parameters and CFD calculation parameters; reads the static pressure value and grid center coordinates of each grid surface unit at the aperture wall boundary in each CFD iterative calculation; and calculates the mass flow flux within each grid surface unit at the aperture wall boundary using the static pressure value and grid center coordinates as parameters of the called calculation function in each CFD iterative calculation, thereby replacing the mass flow flux in the previous generation of iterative calculations and completing the iterative calculations. The present invention avoids the problem of low precision caused by incomplete consideration of various influencing factors and the rough functional relationship between the various influencing factors in the prior art; and improves the efficiency of adjusting the calculation state by dynamically acquiring flow field parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of transonic wind tunnel testing, and in particular relates to a method for obtaining boundary conditions of an opening wall for CFD calculation of a transonic wind tunnel. Background Art

[0002] Wind tunnel experiments provide detailed aerodynamic data for aircraft design and other industrial designs. The wind tunnel walls and other experimental equipment cause differences between the experimental model in the wind tunnel environment and the real working environment, which will reduce the validity of the wind tunnel test data. In order to increase the accuracy of wind tunnel test data, it is necessary to correct the wind tunnel measurement data. With the development of computer equipment and computational fluid dynamics (CFD), the CFD method is used to simulate and calculate the aerodynamic data of the experimental object under wind tunnel and far-field boundary conditions respectively, and the difference is the correction value. In addition, due to the physical limitations of the wind tunnel measurement equipment, the CFD method can capture some details of the wind tunnel flow field that are difficult to measure.

[0003] Transonic wind tunnels use slots or holes in the test section to reduce congestion caused by the model, supports, and wall boundary layer growth, as well as shock wave reflection interference generated by the model under transonic conditions. However, the complex wall flow of transonic wind tunnel openings can produce wall interference. Furthermore, direct simulation modeling of the wall to obtain simulated wind tunnel test data is unsuitable for large-scale, multi-condition applications due to model complexity, large mesh size, and slow convergence. To improve the efficiency of CFD calculations for wall interference, the wall pressure information method and the permeable wall property method have been developed. In simulations, the holes and stagnation chambers are removed from the opening wall, and the wall flow information from the wall pressure information method and the permeable wall property method is assigned to this boundary, thereby reducing the mesh size and simplifying the wall boundary conditions. The wall pressure information method was widely used to correct for wall interference in the 1980s and 1990s. The wall flow information is obtained from wall measurements during wind tunnel experiments.

[0004] The wall flow information used in the wall pressure information method is the static pressure distribution measured by piezometers installed on the walls of the experimental section during wind tunnel experiments. This provides a relatively intuitive representation of the flow field near the aperture wall, but using it as a simplified aperture wall boundary condition fails to adequately characterize the flow within the aperture. Furthermore, measurements must be performed for each experiment, which is cumbersome and lacks precision in capturing detailed information. Increasing the number of piezometers to improve measurement accuracy introduces additional interference. The permeable wall property method, based on the physical structure of the aperture wall pores, studies the flow characteristics within and near the aperture wall, providing a more realistic representation of the flow state at the aperture wall, simplifying the experimental steps and increasing the efficiency of the aperture wall interference correction.

[0005] The permeability of the transonic wind tunnel opening wall is related to the hole geometry and wind tunnel flow parameters. When studying the boundary layer exhaust flow of supersonic inlets, Harloff established a hole flow model with the pressure difference on both sides of the hole and the local Mach number as the influencing parameters under different hole depth-to-diameter ratios. Domestic researchers have added the boundary layer displacement thickness influencing parameter, all in order to increase the impact analysis of flow field details and improve the accuracy of the model. In order to increase the scope of application of the model, domestic researchers have added the hole inclination angle influence analysis, but the free flow Mach number and boundary layer displacement thickness influencing parameters under different inclination angle holes all use the same coefficients as the right-angle hole. Summary of the Invention

[0006] Purpose of the invention: The present invention provides a method for obtaining the boundary conditions of the opening wall for CFD calculations in transonic wind tunnels, which solves the high cost problem caused by directly using the opening wall CFD calculation in related technologies and the low accuracy and small applicability of other boundary expressions.

[0007] Technical solution: The present invention provides a method for obtaining the boundary conditions of an opening wall for CFD calculation in a transonic wind tunnel, which specifically includes the following steps:

[0008] (1) Obtain wind tunnel parameters in advance;

[0009] (2) Extract the surface average Mach number, surface average static pressure, surface average dynamic pressure and mass flow flux at the wind tunnel inlet;

[0010] (3) Extract the static pressure value and the coordinates of the grid center point in each grid calculation unit at the boundary of the opening wall;

[0011] (4) In each grid calculation unit at the boundary of the opening wall, a mass flow flux calculation function is selected according to the wind tunnel parameters in step (1);

[0012] (5) using the surface average Mach number, surface average static pressure value, surface average dynamic pressure and mass flow rate at the wind tunnel inlet in step (2) and the static pressure value and grid center point coordinates of each grid calculation unit on the opening wall boundary in step (3) as the independent variables of the mass flow flux calculation function in each calculation grid unit;

[0013] (6) Calculate the mass flow flux corresponding to each grid calculation unit from the independent variables corresponding to each grid calculation unit in step (5) and the calculation function in step (4), and overwrite the original value with the mass flow flux;

[0014] (7) When each grid calculation unit on the opening wall boundary completes step (6), another CFD iterative calculation of the entire wind tunnel flow field is carried out, that is, steps (2) to (6) are repeated until the physical quantities of the entire flow field tend to be stable and the residual converges.

[0015] Furthermore, the wind tunnel parameters include the diameter, depth, inclination angle and opening ratio of the wind tunnel opening wall.

[0016] Furthermore, the calculation function of the mass flow flux of the opening wall in step (4) is composed of the following:

[0017] m=m′m=m′·m inlet

[0018]

[0019] △Cp=(P zs -P wt ) / Q inlet

[0020] Where m is the mass flow flux to be calculated; m′ is the dimensionless value of the mass flow flux; m inlet is the extracted wind tunnel inlet mass flow flux; Ma is the extracted wind tunnel inlet Mach number; D is the input aperture; α0 is the input target opening wall porosity; θ is the input target opening wall hole inclination angle; P zs is the extracted average static pressure at the inlet surface; P wt is the static pressure value of the extracted mesh surface unit; Q inlet is the extracted average inlet dynamic pressure, δ * is the boundary layer displacement thickness calculated based on the extracted grid unit center coordinates and the empirical formula of the flat plate boundary layer; d, e, i, and j are all constant coefficients; A Ma is the Mach number slope influencing factor; A is the influence factor of boundary layer displacement thickness slope; θ B is the influencing factor of the hole inclination angle slope; Ma is the Mach number intercept influence factor; B is the boundary layer displacement thickness intercept influence factor; θ is the hole inclination angle intercept influencing factor.

[0021] Furthermore, the following:

[0022] Mach number slope influence factor A Ma It is composed of a quadratic function relationship: A Ma =a1·Ma 2 +a2·Ma;

[0023] Boundary layer displacement thickness slope influencing factor It is composed of logarithmic function relationships:

[0024] Hole inclination angle slope influence factor A θ It is composed of a quartic function relationship: A θ=c1·θ 4 +c2·θ 3 +c3·θ 2 +c4θ;

[0025] Mach number intercept influence factor B Ma It is composed of a linear function relationship: B Ma =f·Ma;

[0026] Boundary layer displacement thickness intercept influencing factor It is composed of power function relationships:

[0027] Hole inclination angle intercept influence factor B θ It is composed of inverse relation numbers:

[0028] Among them, a1, a2, b, c1, c2, c3, c4, d, i, f, g1, g2, h1 and h2 are all constant coefficients.

[0029] Furthermore, the implementation process of step (7) is as follows:

[0030] S1: Initialize the flow field, compile and load the boundary condition program;

[0031] S2: Load the GUI program, and the boundary condition program obtains the wind tunnel opening wall aperture D, depth L, inclination angle and opening ratio α0 input by the GUI program;

[0032] S3: Start iterative loop calculation;

[0033] S4: In each iterative calculation, the boundary condition program reads the static pressure value P of each grid surface unit on the opening wall boundary i and the coordinates of the grid center point (x i ,y i ,z i );

[0034] S5: The program reads the static pressure value P of the mesh unit on the boundary surface of the opening wall. i , static pressure at wind tunnel entrance P zs and the dynamic pressure value Q at the wind tunnel entrance, calculate the pressure difference ΔCp of each grid surface unit at the opening wall boundary according to the following formula;

[0035] ΔCp=(P i -P zs ) / Q

[0036] S6: The program retrieves the constant coefficient of the mass function based on the wind tunnel hole diameter D, hole depth L, and hole inclination angle θ obtained by the GUI program;

[0037] S7: Based on the grid unit coordinates of the opening wall boundary surface, calculate the distance between the center of each grid surface and the wind tunnel entrance, and calculate the boundary layer displacement thickness based on the flat plate boundary layer.

[0038] S8: Based on the wind tunnel inlet free flow Mach number Ma read by the program and the constant coefficient retrieved in S6, the Mach number slope influencing factor is calculated using a quadratic function relationship, and the Mach number intercept influencing factor is calculated using a linear function relationship;

[0039] S9: Based on the hole inclination angle θ inputted by the GUI and the constant coefficient retrieved in S6, a quartic function relationship is used to calculate the hole inclination angle slope influence factor, and a reciprocal function relationship is used to calculate the hole inclination angle intercept influence factor;

[0040] S10: Based on the boundary layer thickness at each mesh element of the opening wall boundary surface calculated in S7 and the constant coefficient retrieved in S6, the boundary layer displacement thickness slope is calculated using a logarithmic function relationship and the intercept influence factor is calculated using a power function relationship;

[0041] S11: Substitute the influencing factors in S8, S9 and S10 and some constant coefficients in S6 into the mass flow calculation function to calculate the magnitude and direction of the mass flow flux value of each grid surface unit;

[0042] S12: assigning the mass flow flux and direction of each grid surface unit calculated in S11 to the grid surface where the opening wall is located as the opening wall boundary condition;

[0043] S13: Perform flow field calculations, including mass, momentum, energy, turbulence, and transport equations;

[0044] S14: Complete one flow field iterative calculation and determine whether it has converged. If not, repeat the above calculation of the opening wall boundary and flow field.

[0045] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention avoids the problem of low precision caused by incomplete consideration of various influencing factors and rough functional relationships of various influencing factors in the prior art by adopting a mass flow flux calculation function composed of the Mach number slope influencing factor of a quadratic function relationship, the Mach number intercept influencing factor of a linear function relationship, the boundary layer displacement thickness slope of a logarithmic function relationship and the intercept influencing factor of a power function relationship, by adopting a quartic function relationship; the working conditions are quickly changed through GUI interface input, the steps of modifying programs, compiling programs and loading programs are reduced, the scope of application and operating performance are improved, the problems in the prior art are solved, and corresponding effects are achieved; by adaptively adjusting the resident chamber pressure, the frequency of manual adjustment is reduced, and the overall work efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the CFD calculation flow chart of the transonic wind tunnel based on the boundary conditions of the opening wall. DETAILED DESCRIPTION

[0047] The present invention will be further described in detail below with reference to the accompanying drawings.

[0048] The present invention provides a method for obtaining boundary conditions of an opening wall for CFD calculation in a transonic wind tunnel, which specifically comprises the following steps:

[0049] Step 1: Receive the input wind tunnel parameters: wind tunnel opening wall aperture, depth, inclination angle and opening ratio.

[0050] Step 2: After each iterative calculation of the entire wind tunnel flow field is completed, the surface average Mach number, surface average static pressure, surface average dynamic pressure and mass flow flux at the wind tunnel inlet are extracted.

[0051] Step 3: After each iterative calculation of the entire wind tunnel flow field is completed, the static pressure value and the coordinates of the grid center point are extracted in each grid calculation unit on the opening wall boundary.

[0052] Step 4: After each iterative calculation of the entire wind tunnel flow field is completed, the mass flow flux calculation function is selected in each grid calculation unit on the opening wall boundary according to the wind tunnel parameters in step 1.

[0053] The mass flow flux calculation function consists of the following:

[0054] m=m′·m inlet

[0055]

[0056] △Cp=(P zs -P wt ) / Q inlet

[0057] Where m is the mass flow flux to be calculated; m′ is the dimensionless value of the mass flow flux; m inlet is the mass flow flux at the wind tunnel inlet; Ma is the Mach number at the wind tunnel inlet; D is the aperture set by input; α0 is the porosity of the target opening wall set by input; θ is the inclination angle of the target opening wall hole set by input; P zs is the extracted static pressure at the wind tunnel inlet; P wt is the static pressure value of the grid surface unit read; δ * A is the boundary layer displacement thickness calculated based on the read grid cell center coordinates and the empirical formula for the flat plate boundary layer; d and i are both constant coefficients. Ma is the Mach number slope influencing factor; A is the influence factor of boundary layer displacement thickness slope; θ B is the influencing factor of the hole inclination angle slope; Ma is the Mach number intercept influence factor; B is the boundary layer displacement thickness intercept influence factor; θ is the hole inclination angle intercept influencing factor.

[0058] Mach number slope influence factor A Ma It is composed of quadratic function relationships:

[0059] A Ma =a1·Ma 2 +a2·Ma

[0060] Boundary layer displacement thickness slope influencing factors It is composed of logarithmic function relationships:

[0061]

[0062] Hole inclination angle slope influence factor A θ It is composed of the fourth function relationship:

[0063] A θ =c1·θ 4 +c2·θ 3 +c3·θ 2 +c4θ

[0064] Mach number intercept influence factor B Ma It is composed of a linear function relationship:

[0065] B Ma =f·Ma

[0066] Boundary layer displacement thickness intercept influencing factor It is composed of power function relationships:

[0067]

[0068] Hole inclination angle intercept influence factor B θ It is composed of inverse relation numbers:

[0069]

[0070] Among them, a1, a2, b, c1, c2, c3, c4, d, i, f, g1, g2, h1 and h2 are all constant coefficients. The constant coefficients are composed of the following:

[0071] Table 1 Mass flow flux calculation function constant coefficient (inflow)

[0072]

[0073] Table 2 Mass flow flux calculation function constant coefficient table (outflow)

[0074]

[0075]

[0076] The method for determining and selecting the constant coefficient is:

[0077] (1) Receive the target wind tunnel opening wall diameter D and depth L, and determine the value range of L / D, where L is the received and set hole depth.

[0078] If L / D is 0.5, 1.0, and 1.2, the coefficient values ​​in the constant coefficient table are directly used;

[0079] If 0.5<L / D<1.0, the mass flow flux is calculated according to the constant coefficients of L / D of 0.5 and 1.0 respectively, and linear interpolation is performed;

[0080] If 1.0<L / D<1.2, the mass flow flux is calculated according to the constant coefficients of L / D of 1.0 and 1.2 respectively, and linear interpolation is performed;

[0081] (2) Receive the set target wind tunnel opening wall hole inclination angle θ.

[0082] If θ>90°, select the constant coefficients in Table 1 (inflow);

[0083] If θ<90°, select the constant coefficients in Table 2 Constant Coefficients (Outflow) table.

[0084] Step 5: After each iterative calculation of the entire wind tunnel flow field is completed, the surface average Mach number, surface average static pressure value, surface average dynamic pressure and mass flow rate at the wind tunnel inlet in step 2 and the static pressure value and grid center point coordinates of each grid calculation unit at the opening wall boundary in step 3 are used as the independent variables of the mass flow flux calculation function in each calculation grid unit.

[0085] Step 6: After each iterative calculation of the entire wind tunnel flow field is completed, the mass flow flux corresponding to each grid calculation unit is calculated based on the independent variables corresponding to each grid calculation unit in step 5 and the calculation function in step 4, and the mass flow flux is used to overwrite the original value.

[0086] Step 7: When each grid calculation unit of the opening wall boundary completes step 6, another CFD iterative calculation of the entire wind tunnel flow field is carried out. Figure 1 As shown:

[0087] S1: Initialize the flow field, compile and load the boundary condition program;

[0088] S2: Load the GUI program, and the boundary condition program obtains the wind tunnel opening wall aperture D, depth L, inclination angle and opening ratio α0 input by the GUI program;

[0089] S3: Start iterative loop calculation;

[0090] S4: In each iterative calculation, the boundary condition program extracts the static pressure value P of each grid surface unit at the opening wall boundary i and the coordinates of the grid center point (x i ,y i ,z i );

[0091] S5: The program reads the static pressure value P of the surface grid cell i , static pressure at wind tunnel entrance P zs and the dynamic pressure value Q at the wind tunnel entrance, calculate the pressure difference ΔCp of each grid surface unit at the opening wall boundary according to the following formula;

[0092] ΔCp=(P i -P zs ) / Q

[0093] S6: The program retrieves the constant coefficient of the mass function based on the wind tunnel hole diameter D, hole depth L, and hole inclination angle θ obtained by the GUI program;

[0094] S7: Based on the grid unit coordinates of the opening wall boundary surface, calculate the distance between the center of each grid surface and the wind tunnel entrance, and calculate the boundary layer displacement thickness based on the flat plate boundary layer.

[0095] S8: Based on the wind tunnel inlet free flow Mach number Ma read by the program and the constant coefficient retrieved in step S6, a quadratic function relationship is used to calculate the Mach number slope influence factor, and a linear function relationship is used to calculate the Mach number intercept influence factor;

[0096] S9: Based on the hole inclination angle θ inputted by the GUI and the constant coefficient retrieved in step S6, a quartic function relationship is used to calculate the hole inclination angle slope influence factor, and a reciprocal function relationship is used to calculate the hole inclination angle intercept influence factor;

[0097] S10: Based on the boundary layer thickness at each mesh unit of the opening wall boundary surface calculated in step S7 and the constant coefficient retrieved in step S6, a logarithmic function relationship is used to calculate the boundary layer displacement thickness slope and a power function relationship is used to calculate the intercept influence factor;

[0098] S11: Substitute the influencing factors in steps S8, S9, and S10 and some constant coefficients in S6 into the mass flow calculation function to calculate the magnitude and direction of the mass flow flux value of each grid surface unit;

[0099] S12: assigning the mass flow flux and direction of each grid surface unit calculated in S11 to the grid surface where the opening wall is located as the opening wall boundary condition;

[0100] S13: Perform flow field calculations, including mass, momentum, energy, turbulence, and transport equations;

[0101] S14: Complete one flow field iterative calculation and determine whether it has converged. If not, repeat the above calculation of the opening wall boundary and flow field.

[0102] The present invention utilizes a mass flow flux calculation function composed of a quadratic Mach number slope influence factor, a linear Mach number intercept influence factor, a logarithmic boundary layer displacement thickness slope and power intercept influence factors, a quartic hole tilt angle slope influence factor, and a reciprocal hole tilt angle intercept influence factor. This function avoids the problems of incomplete consideration of various influencing factors and the resulting low precision caused by the rough functional relationships of the influencing factors in the prior art, as well as the limited applicability of the prior art for specific wind tunnels with fixed depth-to-diameter ratios and hole tilt angles. By dynamically acquiring wind tunnel inlet flow field parameters and wall flow parameters and performing adaptive iterative calculations, the efficiency of adjusting the wind tunnel calculation state is improved.

Claims

1. A method for obtaining boundary conditions of opening walls for CFD calculations in transonic wind tunnels, characterized in that: The following steps are involved: (1) Obtain wind tunnel parameters in advance; (2) Extract the surface average Mach number, surface average static pressure, surface average dynamic pressure and mass flow flux at the wind tunnel inlet; (3) Extract the static pressure value and the coordinates of the grid center point in each grid calculation unit at the boundary of the opening wall; (4) In each grid calculation unit at the boundary of the opening wall, a mass flow flux calculation function is selected according to the wind tunnel parameters in step (1); (5) using the surface average Mach number, surface average static pressure value, surface average dynamic pressure and mass flow rate at the wind tunnel inlet in step (2) and the static pressure value and grid center point coordinates of each grid calculation unit on the opening wall boundary in step (3) as the independent variables of the mass flow flux calculation function in each calculation grid unit; (6) Calculate the mass flow flux corresponding to each grid calculation unit from the independent variables corresponding to each grid calculation unit in step (5) and the calculation function in step (4), and overwrite the original value with the mass flow flux; (7) When each grid calculation unit on the opening wall boundary completes step (6), another CFD iterative calculation of the entire wind tunnel flow field is carried out, that is, steps (2) to (6) are repeated until all physical quantities of the entire flow field tend to be stable and the residual converges; The calculation function of the mass flow rate of the opening wall in step (4) is composed of the following: m=m′·m inlet ΔCp=(P zs -P wt ) / Q inlet Where m is the mass flow flux to be calculated; m′ is the dimensionless value of the mass flow flux; m inlet is the extracted wind tunnel inlet mass flow flux; Ma is the extracted wind tunnel inlet Mach number; D is the input aperture; α0 is the input target opening wall porosity; θ is the input target opening wall hole inclination angle; P zs is the extracted average static pressure at the inlet surface; P wt is the static pressure value of the mesh surface unit read; Q inlet is the extracted average inlet dynamic pressure, δ * is the boundary layer displacement thickness calculated based on the read grid unit center coordinates and the empirical formula of the flat plate boundary layer; d, e, i and j are all constant coefficients; A Ma is the Mach number slope influencing factor; A is the influence factor of boundary layer displacement thickness slope; θ B is the influencing factor of the hole inclination angle slope; Ma is the Mach number intercept influence factor; B is the boundary layer displacement thickness intercept influence factor; θ is the hole inclination angle intercept influencing factor.

2. The method for obtaining the boundary conditions of the opening wall for CFD calculation in a transonic wind tunnel according to claim 1, characterized in that: The wind tunnel parameters include the diameter, depth, inclination angle and opening ratio of the wind tunnel opening wall.

3. The method for obtaining the boundary conditions of the opening wall for CFD calculation in a transonic wind tunnel according to claim 1, characterized in that: Mach number slope influence factor A Ma It is composed of a quadratic function relationship: A Ma =a1·Ma 2 +a2·Ma; Boundary layer displacement thickness slope influencing factors It is composed of logarithmic function relationships: Hole inclination angle slope influence factor A θ It is composed of a quartic function relationship: A θ =c1·θ 4 +c2·θ 3 +c3·θ 2 +c4θ; Mach number intercept influence factor B Ma It is composed of a linear function relationship: B Ma =f·Ma; Boundary layer displacement thickness intercept influencing factor It is composed of power function relationships: Hole inclination angle intercept influence factor B θ It is composed of inverse relation numbers: Among them, a1, a2, b, c1, c2, c3, c4, d, i, f, g1, g2, h1 and h2 are all constant coefficients.

4. The method for obtaining the boundary conditions of the opening wall for CFD calculation in a transonic wind tunnel according to claim 1, characterized in that: The implementation process of step (7) is as follows: S1: Initialize the flow field, compile and load the boundary condition program; S2: Load the GUI program, and the boundary condition program obtains the wind tunnel opening wall aperture D, depth L, inclination angle θ and opening ratio α0 input by the GUI program; S3: Start iterative loop calculation; S4: In each iterative calculation, the boundary condition program reads the static pressure value P of each grid surface unit on the opening wall boundary i and the coordinates of the grid center point (x i ,y i ,z i ); S5: The program extracts the static pressure value P of the mesh element on the boundary surface of the opening wall. i , static pressure at wind tunnel entrance P zs and the dynamic pressure value Q at the wind tunnel entrance, calculate the pressure difference ΔCp of each grid surface unit at the opening wall boundary according to the following formula; ΔCp=(P i -P zs ) / Q S6: The program retrieves the constant coefficient of the mass function based on the wind tunnel hole diameter D, hole depth L, and hole inclination angle θ obtained by the GUI program; S7: Based on the grid unit coordinates of the opening wall boundary surface, calculate the distance between the center of each grid surface and the wind tunnel entrance, and calculate the boundary layer displacement thickness based on the flat plate boundary layer. S8: Based on the freeflow Mach number Ma read by the program and the constant coefficient retrieved in S6, the Mach number slope influencing factor is calculated using a quadratic function relationship, and the Mach number intercept influencing factor is calculated using a linear function relationship; S9: Based on the hole inclination angle θ inputted by the GUI and the constant coefficient retrieved in S6, a quartic function relationship is used to calculate the hole inclination angle slope influence factor, and a reciprocal function relationship is used to calculate the hole inclination angle intercept influence factor; S10: Based on the boundary layer thickness at each mesh element of the opening wall boundary surface calculated in S7 and the constant coefficient retrieved in S6, the boundary layer displacement thickness slope is calculated using a logarithmic function relationship and the intercept influence factor is calculated using a power function relationship; S11: Substitute the influencing factors in S8, S9 and S10 and some constant coefficients in S6 into the mass flow calculation function to calculate the magnitude and direction of the mass flow flux value of each grid surface unit; S12: assigning the mass flow flux and direction of each grid surface unit calculated in S11 to the grid surface where the opening wall is located as the opening wall boundary condition; S13: Perform flow field calculations, including mass, momentum, energy, turbulence, and transport equations; S14: Complete one flow field iterative calculation and determine whether it has converged. If not, repeat the above calculation of the opening wall boundary and flow field.

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