Test section subsonic flow field quality evaluation method, electronic device and storage medium

Abstract

The test section subsonic flow field quality evaluation method, electronic equipment and storage medium belong to the field of experimental aerodynamics. In order to reduce the complexity of the slot type surface or the hole distribution of the open hole wall, the improved Keller panel method is used to calculate the disturbance velocity basic solution of the test section subsonic flow field, and the disturbance velocity database of the test section subsonic flow field is constructed. The singularity method is used to construct the expression of the test model; the singularity strength of the lift effect of the test model is calculated; the singularity strength of the blockage effect of the test model is calculated; the singularity strength of the lift effect of the test model is used to calculate the lift effect of the model and the support, and the singularity strength of the blockage effect of the test model is used to calculate the blockage effect of the model and the support, and the lift effect and the blockage effect jointly constitute the disturbance of the test section gas permeable wall to the flow field. The present application can be applied to the subsonic flow field quality evaluation of various types of test section wall panels, and is simple to operate and high in calculation efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aerodynamics, and particularly relates to a test section subsonic flow field quality evaluation method, an electronic device and a storage medium. BACKGROUND

[0002] The test section of a transonic wind tunnel is divided into a solid wall test section and a porous wall test section, and the porous wall test section mainly includes a slotted wall test section and a perforated wall test section. Different types of porous wall test sections interfere with the flow field of a model test during subsonic testing. In the past, in order to obtain the interference of the test section on the flow field, a large number of wind tunnel test researches or CFD calculation researches need to be conducted on various porous walls, which makes this work quite expensive and time-consuming. Although CFD applications are very extensive, simulating a slotted wall test section or a perforated wall test section is still a time-consuming and laborious work, especially at the beginning of designing a test section, a large amount of comparative analysis work needs to be conducted on the slot profile of the slotted wall or the hole distribution of the perforated wall. SUMMARY

[0003] In order to reduce the complexity and workload of the comparative analysis work on the slot profile of the slotted wall or the hole distribution of the perforated wall, the present application provides a test section subsonic flow field quality evaluation method, an electronic device and a storage medium.

[0004] To achieve the above object, the present application realizes by the following technical scheme:

[0005] A test section subsonic flow field quality evaluation method, comprising the following steps:

[0006] S1, calculating a disturbance velocity basic solution of a test section subsonic flow field by using an improved Keller panel method, and constructing a disturbance velocity database of the test section subsonic flow field;

[0007] S2, constructing an expression of a test model by using a singularity method;

[0008] S3, calculating a singularity strength of a lift effect of the test model according to the expression of the test model constructed in step S2;

[0009] S4, calculating a singularity strength of a blockage effect of the test model according to the expression of the test model constructed in step S2 and the singularity strength of the lift effect of the test model obtained in step S3;

[0010] S5, using the singularity strength of the lift effect of the test model calculated in step S3 to calculate a lift effect of a model and a support, and using the singularity strength of the blockage effect of the test model calculated in step S4 to calculate a blockage effect of the model and the support, and the lift effect and the blockage effect jointly constitute a disturbance of a test section porous wall on a flow field.

[0011] Further, the specific implementation method of step S1 comprises the following steps:

[0012] S1.1 The subsonic flow field in the test section includes a solid wall, a free jet boundary, an orifice wall, a slotted wall without viscosity influence, and a slotted wall with viscosity influence. The boundary conditions of the subsonic flow field in the test section are set as follows:

[0013]

[0014] Where C1 is the first boundary condition parameter, C2 is the second boundary condition parameter, C3 is the third boundary condition parameter, and C4 is the fourth boundary condition parameter. Let x be the velocity potential of the flow field, x be the axial coordinate, and n be the normal coordinate.

[0015] S1.2 The formula for calculating the total velocity potential of the permeable wall boundary is:

[0016] φ=φ m +φ w

[0017] Where, φ m Let m be the total velocity potential of the experimental model, and φ be the experimental model. w Let w be the total velocity potential of the permeable wall;

[0018] S1.3 and S2: The total velocity potential of the test model and the total velocity potential of the permeable wall satisfy the boundary conditions of the subsonic flow field in the test section of step S1.1. Therefore, the calculation formula is as follows:

[0019]

[0020] S1.4. Model the permeable wall using the improved Keller surface method. Set the center of each mesh of the permeable wall to a point source with a slope of σ'. The velocity potential function φ of the i-th row of the permeable wall mesh... wi The expression is:

[0021]

[0022] in, Let σ' be the velocity potential function at the center of the grid in the i-th row and j-th column of the permeable wall. j Let be the slope of the point source at the center of the grid in column j;

[0023] And the velocity potential function at the center of the permeable wall grid The calculation formula is:

[0024]

[0025] The coordinates of the corner points of the wall grid of the permeable wall are (ξ,η,ζ), and B is the downstream boundary;

[0026] S1.5, then according to the calculation formula of step S1.3 and step S1.4, the following is obtained:

[0027]

[0028]

[0029]

[0030] Wherein, a ij is the velocity potential function of the grid center satisfying the boundary condition calculation result, is the velocity potential generated by the model at the i-th row grid, b i is the velocity potential generated by the model at the i-th row grid satisfying the negative value of the boundary condition calculation result;

[0031] The disturbance velocity of the permeable wall to the subsonic flow field of the test section is calculated as:

[0032]

[0033]

[0034]

[0035] Wherein, k is any one of n, u w is the axial disturbance velocity of the permeable wall to the subsonic flow field of the test section, u w is the lateral disturbance velocity of the permeable wall to the subsonic flow field of the test section, ω w is the normal disturbance velocity of the permeable wall to the subsonic flow field of the test section;

[0036] By calculating the flow field disturbance velocity of the unit strength singularity of the model, a database of the disturbance velocity of the subsonic flow field of the test section of the unit singularity is constructed.

[0037] Further, the specific implementation method of step S2 includes the following steps:

[0038] S2.1, construct the expression of source or sink, the expression of line dipole, the velocity potential of unit source or sink The expression of the velocity potential of the unit line dipole is:

[0039]

[0040] Wherein, (x, y, z) is the spatial position coordinate of the space other than the source or sink, (x0, y0, z0) is the spatial position coordinate of the source or sink, and σ is the unit singularity strength;

[0041] The expression of the velocity potential of the unit line dipole is: The expression of the velocity potential of the unit line dipole is:

[0042]

[0043] ξ0=x0

[0044] η0=y0·cosθ-z0·sinθ

[0045] ζ0=y0·sinθ+z0·cosθ

[0046] wherein θ is a directional angle of the line dipole;

[0047] S2.2, using the singularity method to construct an expression of the test model, including an expression of a fuselage of the test model, an expression of a separated wake of the test model, an expression of a wing and a tail of the test model;

[0048] The expression of the fuselage of the test model is:

[0049] σ k* =λ k ·σ * , k=1,2,…2μ

[0050] λ k =-λ k-μ , k=μ+1,μ+2,…2μ

[0051] wherein σ k* is a fuselage strength of the test model, λ k is a specific gravity coefficient, σ * is a unit singularity strength of the fuselage using a source or sink, μ is a number of fuselage sources, and 2μ is a number of fuselage sources or sinks;

[0052] The expression of the separated wake of the test model is:

[0053] σ k** =λ k ·σ ** , k=2μ+1,2μ+2…ε

[0054] wherein σ k** is a separated wake strength of the test model, σ ** is a unit singularity strength of the separated wake using a source or sink, and ε is a number of fuselage sources or sinks and wake sources;

[0055] The expression of the wing of the test model is, and the expression of the tail is:

[0056]

[0057]

[0058] wherein σ dΔs is the strength of the wing of the test model d λ is the span interval of the wing of the test model d Γ is the relative density coefficient of the wing of the test model d U is the circulation of the wing of the test model ref σ is the velocity of the reference point of the flow field t Δs is the strength of the tail of the test model t λ is the span interval of the tail of the test model t Γ is the relative density coefficient of the tail of the test model t U is the circulation of the tail of the test model

[0059] S2.3, the disturbance velocity of the test section subsonic flow field obtained in step S1 is decomposed according to the linear subsonic linear superposition principle, and divided by the velocity of the reference point of the flow field U ref , the calculation formula is:

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] wherein σ is the strength of the singular point, σ k u (k) is the strength of the kth singular point, v * (k) is the axial disturbance velocity of the kth point, v * (k) is the lateral disturbance velocity of the kth point, ω * (k) is the normal disturbance velocity of the kth point, u (k) is the axial disturbance velocity of the kth point normalized by the strength, v (k) is the lateral disturbance velocity of the kth point normalized by the strength, ω (k) is the normal disturbance velocity of the kth point normalized by the strength.

[0066] Further, the specific implementation method of step S3 includes the following steps:

[0067] S3.1, the lift and the pitching moment of the test model include the lift of the wing and the tail, the pitching moment of the wing and the tail, wherein the calculation formula of the lift of the wing and the tail is:

[0068]

[0069] wherein L is the lift of the wing and the tail, L d u (i) is the lift of the ith segmented wing, Lt (j) is the lift of the jth segment tail wing, n d is the number of segments of the wing, n t denotes the number of segments of the tail wing;

[0070] The formula for calculating the pitching moment of the wing and tail wing is:

[0071]

[0072] where P is the pitching moment of the wing and tail wing, x mr is the x-coordinate of the moment reference point, x d (i) is the x-coordinate of the i th segment wing lift action point, x t (j) is the x-coordinate of the jth segment tail wing lift action point, P is the pitching moment;

[0073] S3.2, according to the Kutta-Joukowski formula, the lift in step S3.1 is rewritten as:

[0074]

[0075] where C L is the lift coefficient of the test model, ρ is the air density, U is the wind speed, and c is the average aerodynamic chord length;

[0076] The formula for calculating the air density is:

[0077]

[0078] where M ref is the Mach number of the reference point, ∈ is the blockage factor, and the initial value of ∈ is 0.01;

[0079] S3.3, the formula for calculating the normalized linear dipole strength is constructed as:

[0080]

[0081] S3.4, according to the expression of the wing of the test model obtained in step S2, the expression of the tail wing, and the normalized linear dipole strength constructed in step S3.3, the normalized linear dipole strength of the wing and the normalized linear dipole strength of the tail wing are calculated:

[0082]

[0083]

[0084] where σ d (i) is the wing strength of the i th segment test model, σ t (j) is the tail wing strength of the jth segment test model, σ dσ t is the normalized line dipole strength of the tail wing

[0085] S3.5, parameter setting is as follows:

[0086]

[0087]

[0088]

[0089]

[0090] Wherein, a1 is the specific gravity coefficient λ d of the test model wing, the product of the sum of the wing span interval Δs d of the test model and a2 is the specific gravity coefficient λ t of the test model tail wing, the product of the sum of the tail wing span interval Δs t of the test model, b1 is the specific gravity coefficient λ d of the test model wing, the product of the sum of the wing lift point to the moment reference point distance and the wing span interval Δs d of the test model, b2 is the specific gravity coefficient λ t of the test model tail wing, the product of the sum of the tail wing lift point to the moment reference point distance and the tail wing span interval Δs t of the test model.

[0091] Then the circulation of the test model wing and the circulation of the test model tail wing are calculated as:

[0092]

[0093]

[0094] Wherein, ρ ref is the air density of the reference point; the blockage factor ∈ is obtained by iterative calculation, and step S3 is recalculated after step S5 is completed, until the error of ∈ is less than 0.001.

[0095] Further, the specific implementation method of step S4 includes the following steps:

[0096] S4.1, the measured disturbance velocity of the permeable wall is equal to the sum of the disturbance velocity generated by the lift effect on the permeable wall and the disturbance velocity generated by the model blockage effect on the permeable wall, and the calculation formula is:

[0097]

[0098] Wherein, δ is the measuring point of the porous wall, U e is the empty wind tunnel speed, u t is the axial disturbance speed generated by the test model and support on the porous wall, u t s is the axial disturbance speed generated by the support on the porous wall;

[0099] S4.2, set the number of measuring points on the porous wall as m, and solve σ * and σ ** by the least square fitting method, and the calculation formula is:

[0100]

[0101] Wherein, A m×2 is the matrix of the sum of the specific gravity coefficient of the fuselage and the wake and the product of the normalized axial disturbance speed, B m×1 is the vector of the result of the measured porous wall disturbance speed minus the disturbance speed generated by the lift effect on the porous wall, X 2×1 is the vector of the unit singular point strength of the fuselage source and the wake source;

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108] Wherein, a δ,1 is the sum of the specific gravity coefficient of the fuselage and the product of the normalized axial disturbance speed, a δ,2 is the sum of the specific gravity coefficient of the wake and the product of the normalized axial disturbance speed, b k is the result of the measured porous wall disturbance speed minus the disturbance speed generated by the lift effect on the porous wall.

[0109] Further, the specific implementation method of step S5 includes the following steps:

[0110] S5.1, set the calculation formula of the blockage factor as:

[0111]

[0112] Wherein, ∈ (v) is the total blockage factor of the model and the support, ∈ m (ψ) is the blockage factor of the position point of the test model in the wind tunnel flow field, ∈s (ψ) is the blockage factor of the position point supported in the flow field of the wind tunnel, ψ represents the position point in the flow field of the wind tunnel, u wm is the axial disturbance velocity generated by the test model and the porous wall in the flow field of the test section, u m is the axial disturbance velocity generated by the test model in the free flow, u ws is the axial disturbance velocity generated by the support and the porous wall in the flow field of the test section, u s is the axial disturbance velocity generated by the support in the free flow, is the axial disturbance velocity generated by the test model in the flow field of the test section, is the axial disturbance velocity generated by the support in the flow field of the test section. and The calculation formula is:

[0113]

[0114] The blockage effect of the flow field disturbance caused by Mach number interference is calculated, and the calculation formula is:

[0115]

[0116] Where, M ∞ is the Mach number far ahead, and γ is the specific heat ratio of air;

[0117] S5.2, relative to the reference point, the flow angle induced by the porous wall includes the lift interference and the disturbance of the flow field by the support, the lift effect of the flow field disturbance caused by the flow angle interference is calculated, and the calculation formula is:

[0118]

[0119] Where, ω wm is the normal disturbance velocity generated by the test model and the porous wall in the flow field of the test section, ω m is the normal disturbance velocity generated by the test model in the free flow, ω ws is the normal disturbance velocity generated by the support and the porous wall in the flow field of the test section, ω s is the normal disturbance velocity generated by the support in the free flow, and α is the flow angle, α m is the flow angle induced by the test model, α s is the flow angle induced by the support, is the normal disturbance generated by the test model in the flow field of the test section, is the axial disturbance generated by the test model in the flow field of the test section. and The calculation formula is:

[0120]

[0121] S5.3, relative to the far front airflow, the calculation formula of the airflow angle induced by the air-permeable wall is:

[0122]

[0123] The electronic device comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the test section subsonic flow field quality evaluation method when executing the computer program.

[0124] The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the test section subsonic flow field quality evaluation method.

[0125] The beneficial effects of the present application are:

[0126] The test section subsonic flow field quality evaluation method provided by the present application is a verified and relatively reliable simulation method, which has the advantages that after the boundary conditions are given, the required results can be obtained in a very short time through program operation. However, the application of this method is limited to the simulation of subsonic flow. The singularity method can simulate the test section wall and the model to obtain the interference of the test section wall on the wind tunnel flow field. Through the test section subsonic flow field quality evaluation method provided by the present application, some test section air-permeable walls with obviously poor effects can be excluded, and better slotted wall slot profiles or open hole distribution of open hole walls can be retained for further CFD or wind tunnel test research.

[0127] The test section subsonic flow field quality evaluation method provided by the present application can be used to analyze the interference of different types of test sections on the flow field. It has the advantages of simple operation and high calculation efficiency, and can quickly evaluate the quality of the test section subsonic flow field.

[0128] The test section subsonic flow field quality evaluation method provided by the present application can be used for subsonic flow field quality evaluation of various types of test section wall panels, and is suitable for solid wall test sections, open hole wall test sections and slotted wall test sections.

[0129] The test section subsonic flow field quality evaluation method provided by the present application provides a large amount of analysis data for the aerodynamic design of the test section, and saves a large amount of calculation time and cost for the design and selection of the test section. BRIEF DESCRIPTION OF DRAWINGS

[0130] Figure 1 The flow chart of the test section subsonic flow field quality evaluation method provided by the present application is shown in the figure;

[0131] Figure 2 The grid coordinates of the point source with a slope of σ' on the wall surface are shown in the figure;

[0132] Figure 3 Singularity plot for the test model of the present invention;

[0133] Figure 4 Lift disturbance factor plot for the model flow field on the wind tunnel axis for different types of porous walls of the present invention. DETAILED DESCRIPTION

[0134] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, i.e., the specific embodiments described are only a part of the embodiments of the present invention, but not all the specific embodiments. The components of the specific embodiments of the present invention generally described and shown in the accompanying drawings can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0135] Therefore, the detailed description of the specific embodiments of the present invention provided below in the accompanying drawings is not intended to limit the scope of the claimed invention, but only represents selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative efforts fall within the scope of the present invention.

[0136] In order to further understand the inventive content, characteristics and effects of the present invention, the following specific embodiments are exemplified, and the accompanying drawings are Figure 1 - the accompanying drawings Figure 4 The detailed description is as follows: Specific embodiment one:

[0138] A test section subsonic flow field quality evaluation method, comprising the following steps:

[0139] S1, using the improved Keller panel method to calculate the disturbance velocity basic solution of the test section subsonic flow field, and constructing the disturbance velocity database of the test section subsonic flow field;

[0140] Further, the specific implementation method of step S1 comprises the following steps:

[0141] S1.1, the test section subsonic flow field includes solid wall, free jet boundary, open hole wall, open slot wall without viscous effect, and open slot wall with viscous effect, and the boundary conditions of the test section subsonic flow field are set as:

[0142]

[0143] Wherein, C1 is the first boundary condition parameter, C2 is the second boundary condition parameter, C3 is the third boundary condition parameter, C4 is the fourth boundary condition parameter, is the velocity potential of the flow field, x is the axial coordinate, and n is the normal coordinate;

[0144] Table 1 Parameter values corresponding to different boundary conditions

[0145]

[0146] The parameter values corresponding to different boundary conditions are shown in Table 1, and the calculation formula of the slot parameter K of the slotted wall is:

[0147]

[0148] where d is the distance between adjacent slots, t is the slot width, and R is a flow characteristic parameter, which is generally obtained by experimental measurement;

[0149] S1.2, the calculation formula of the total velocity potential of the gas permeable wall boundary is:

[0150] φ = φ m + φ w

[0151] where φ m is the total velocity potential of the test model, m is the test model, φ w is the total velocity potential of the gas permeable wall, and w is the gas permeable wall.

[0152] S1.3, the total velocity potential of the test model and the total velocity potential of the gas permeable wall obtained in step S2 satisfy the boundary conditions of the subsonic flow field of the test section in step S1.1, and the calculation formula is:

[0153]

[0154] S1.4, according to the improved Keller panel method, set a point source with a slope of φ' at the center of each grid of the gas permeable wall, and the velocity potential function φ wi of the i-th row of grids of the gas permeable wall is:

[0155]

[0156] where φ is the velocity potential function of the center of the i-th row and j-th column grid of the gas permeable wall, and σ' j is the slope of the point source at the center of the j-th column grid.

[0157] The calculation formula of the velocity potential function φ of the center of the grid of the gas permeable wall is:

[0158]

[0159] where the coordinates of the wall grid angle point of the gas permeable wall are (ξ, η, ζ), and B is the downstream boundary.

[0160] S1.5. Based on the calculation formulas in steps S1.3 and S1.4, we obtain:

[0161]

[0162]

[0163]

[0164] Among them, a ij The velocity potential function at the grid center The calculation results satisfy the boundary conditions. b is the velocity potential generated by the model in the i-th row of the grid. i The velocity potential generated by the model in the i-th row of the grid. The negative value of the calculation result that satisfies the boundary conditions;

[0165] The permeable wall's disturbance velocity on the subsonic flow field of the test section is calculated as follows:

[0166]

[0167]

[0168]

[0169] Where k is any one of n, u w v is the axial perturbation velocity of the permeable wall on the subsonic flow field of the test section. w ω represents the lateral perturbation velocity of the permeable wall on the subsonic flow field in the test section. w The normal perturbation velocity of the permeable wall on the subsonic flow field of the test section;

[0170] By calculating the flow field disturbance velocity at the unit intensity singularity of the expression model, a database of subsonic flow field disturbance velocities at the unit singularity of the test section is constructed.

[0171] S2. Construct the expression for the experimental model using the singularity method;

[0172] Furthermore, the specific implementation method of step S2 includes the following steps:

[0173] S2.1 Construct the expressions for the source or sink, the expression for the linear dipole, and the velocity potential of the unit source or sink. The expression is:

[0174]

[0175] Where (x, y, z) are the spatial coordinates of the source or sink, (x0, y0, z0) are the spatial coordinates of the source or sink, and σ is the unit singularity intensity;

[0176] Velocity potential of a unit linear dipole The expression is:

[0177]

[0178] ξ0=x0

[0179] η0=y0·cosθ-z0·sinθ

[0180] ζ0=y0·sinθ+z0·cosθ

[0181] Where θ is the direction angle of the linear dipole;

[0182] S2.2 Use the singularity method to construct the expression of the test model, including the fuselage expression of the test model, the separation wake expression of the test model, and the wing and tail expressions of the test model;

[0183] The fuselage expression of the experimental model is:

[0184] σ k* =λ k ·σ * k = 1, 2, ..., 2μ

[0185] λ k =-λ k-μ k = μ+1, μ+2, ..., 2μ

[0186] Where, σ k* For the fuselage strength of the test model, λ k σ is the specific gravity coefficient. * The unit singularity intensity of the source or sink used in the fuselage, μ is the number of sources in the fuselage, and 2μ is the number of sources or sinks in the fuselage;

[0187] The separation tail expression of the experimental model is:

[0188] σ k** =λ k ·σ ** k = 2μ+1, 2μ+2…ε

[0189] In the formula, σ k** σ represents the separation wake intensity of the experimental model. ** The unit singularity intensity of the source or sink is used to separate the wake, where ε is the number of fuselage sources or sinks and wake sources;

[0190] The expression for the wing of the experimental model is: [expression here], and the expression for the tail wing is: [expression here]

[0191]

[0192]

[0193] where σ is the singular point strength, σ d is the wing strength of the test model, Δs d is the wing span interval of the test model, λ d is the specific gravity coefficient of the wing of the test model, Γ d is the circulation of the wing of the test model, U ref is the reference point velocity of the flow field; σ t is the tail strength of the test model, Δs t is the tail span interval of the test model, λ t is the specific gravity coefficient of the tail of the test model, Γ t is the circulation of the tail of the test model;

[0194] S2.3, the disturbance velocity of the test section subsonic flow field obtained in step S1 is decomposed according to the linear subsonic linear superposition principle, and divided by the reference point velocity U ref of the flow field, and the calculation formula is:

[0195]

[0196]

[0197]

[0198]

[0199]

[0200] where σ is the singular point strength, σ t is the strength of the k singular point, u * (k) is the axial disturbance velocity of the k point, v * (k) is the transverse disturbance velocity of the k point, ω * (k) is the normal disturbance velocity of the k point, is the axial disturbance velocity of the k point normalized by the strength, is the transverse disturbance velocity of the k point normalized by the strength, is the normal disturbance velocity of the k point normalized by the strength.

[0201] Taking a civil aircraft half model as an example, the singular points of the model are arranged according to Figure 3 and Table 2, a source is arranged at the nose (position 1), a sink is arranged at the tail (position 2), sources are arranged at positions 3 and 4, and a line dipole is arranged at the 1 / 4 chord length of the wing, and the specific gravity coefficient w of the line dipole strength is set according to an elliptic function distribution.

[0202] Table 2 Singular point position distribution and specific gravity coefficient of the half model

[0203] Position number Type x [m] y [m] z [m] Specific gravity coefficient λ 1 Source 0 0 0 1 2 Sink 2.484 0 0 -1 3 Source 1.506 0.297 0 1 4 Source 1.572 0.747 0 1 5 Line dipole 1.032 0.0999 0 0.997 6 Line dipole 1.14 0.3057 0 0.977 7 Line dipole 1.245 0.5112 0 0.934 8 Line dipole 1.353 0.717 0 0.866 9 Line dipole 1.461 0.9228 0 0.766 10 Line dipole 1.569 1.1283 0 0.619 11 Line dipole 1.674 1.3341 0 0.371

[0204] S3, according to the expression of the test model constructed in step S2, the singularity strength of the lift effect of the test model is calculated;

[0205] Further, the specific implementation method of step S3 includes the following steps:

[0206] S3.1, the lift and the pitching moment of the test model include the lift of the wing and the tail, and the pitching moment of the wing and the tail, wherein the calculation formula of the lift of the wing and the tail is:

[0207]

[0208] Wherein, L is the lift of the wing and the tail, L d (i) is the lift of the i-th segmented wing, L t (j) is the lift of the j-th segmented tail, n d is the number of segments of the wing, n t denotes the number of segments of the tail;

[0209] The calculation formula of the pitching moment of the wing and the tail is:

[0210]

[0211] Wherein, P is the pitching moment of the wing and the tail, x mr is the x coordinate of the moment reference point, x d (i) is the x coordinate of the i-th segmented wing lift action point, x t (j) is the x coordinate of the j-th segmented tail lift action point, P is the pitching moment;

[0212] S3.2, according to the Kutta-Joukowski formula, the lift in step S3.1 is rewritten as:

[0213]

[0214] Wherein, C L is the lift coefficient of the test model, ρ is the air density, U is the wind speed, and c is the average aerodynamic chord length;

[0215] The calculation formula of the air density is:

[0216]

[0217] Wherein, M ref is the Mach number of the reference point, ∈ is the blockage factor, and the initial value of ∈ is 0.01;

[0218] S3.3, the calculation formula of the standardized linear dipole strength is constructed as:

[0219]

[0220] S3.4. Based on the expressions for the wing and tail of the test model obtained in step S2, and the standardized linear dipole strength constructed in step S3.3, calculate the standardized linear dipole strength of the wing and the standardized linear dipole strength of the tail:

[0221]

[0222]

[0223] Where, σ d (i) represents the wing strength of the i-th segmented test model, σ t (j) represents the tail fin strength of the j-th segment test model, σ d For the standardized linear dipole strength of the wing, σ t The standardized linear dipole strength for the tail fin;

[0224] S3.5. Set the parameters as follows:

[0225]

[0226]

[0227]

[0228]

[0229] Where a1 is the specific gravity coefficient λ of the experimental model wing. d The sum of the wing span interval Δs of the experimental model d The product parameter, a2 is the specific gravity coefficient λ of the tail fin of the experimental model. t The sum of the tail fin span interval Δs of the experimental model t The product parameter, b1 is the specific gravity coefficient λ of the test model wing. d The sum of the products of the distance between the point of application of the lift force on the wing and the distance between the moment reference point and the wing span interval Δs of the test model. d The product parameter, b2 is the specific gravity coefficient λ of the tail fin of the experimental model. t The sum of the products of the distance between the tail fin lift application point and the moment reference point, and the tail fin span interval Δs of the experimental model. t The product parameters;

[0230] Then the circulation of the test model wing and the circulation of the test model tail were calculated as follows:

[0231]

[0232]

[0233] wherein, ρ ref is the air density of the reference point; the blockage factor ∈ is obtained by iterative calculation, and step S3 is recalculated after step S5 is completed, until the error of ∈ is less than 0.001;

[0234] S4, according to the expression of the test model constructed in step S2, the singularity strength of the lift effect of the test model obtained in step S3, the singularity strength of the blockage effect of the test model is calculated;

[0235] Further, the specific implementation method of step S4 includes the following steps:

[0236] S4.1, the measured disturbance velocity of the porous wall is equal to the sum of the disturbance velocity generated by the lift effect on the porous wall and the disturbance velocity generated by the model blockage effect on the porous wall, and the calculation formula is:

[0237]

[0238] wherein, δ is the measurement point of the porous wall, U e is the wind tunnel speed, u t is the axial disturbance velocity generated by the test model and the support on the porous wall, and u t s is the axial disturbance velocity generated by the support on the porous wall;

[0239] S4.2, the number of measurement points on the porous wall is set to m, and σ * and σ ** are solved by the least square fitting method, and the calculation formula is:

[0240]

[0241] wherein, A m×2 is the matrix of the sum of the specific gravity coefficient of the fuselage and the wake and the product of the normalized axial disturbance velocity, B m×1 is the vector of the result of the measured disturbance velocity of the porous wall minus the disturbance velocity generated by the lift effect on the porous wall, X 2×1 is the vector of the unit singularity strength of the fuselage source and the wake source;

[0242]

[0243]

[0244]

[0245]

[0246]

[0247]

[0248] wherein a δ,1 is the sum of the product of the specific gravity coefficient of the model and the normalized axial disturbance velocity, a δ,2 is the sum of the product of the specific gravity coefficient of the wake and the normalized axial disturbance velocity, b k is the measured disturbance velocity of the porous wall minus the disturbance velocity of the porous wall caused by the lift effect;

[0249] S5, the singularity strength of the lift effect of the test model calculated in step S3 is used to calculate the lift effect of the calculation model and the support, and the singularity strength of the blockage effect of the test model calculated in step S4 is used to calculate the blockage effect of the calculation model and the support, and the lift effect and the blockage effect jointly constitute the disturbance of the test section porous wall to the flow field.

[0250] Further, the specific implementation method of step S5 includes the following steps:

[0251] S5.1, the calculation formula of the blockage factor is set as:

[0252]

[0253] wherein ∈ (v) is the total blockage factor of the model and the support, ∈ m (ψ) is the blockage factor of the test model at the position point in the wind tunnel flow field, ∈ s (ψ) is the blockage factor of the support at the position point in the wind tunnel flow field, ψ represents the position point in the wind tunnel flow field, u wm is the axial disturbance velocity of the test model and the porous wall in the test section flow field, u m is the axial disturbance velocity of the test model in the free flow, u ws is the axial disturbance velocity of the support and the porous wall in the test section flow field, u s is the axial disturbance velocity of the support in the free flow, is the axial disturbance velocity of the porous wall caused by the model to the test section flow field, is the axial disturbance velocity of the porous wall caused by the support to the test section flow field. and The calculation formula is:

[0254]

[0255] The blockage effect of the flow field disturbance caused by the Mach number interference is calculated, and the calculation formula is:

[0256]

[0257] wherein M∞ Ma is the Mach number of the far field, and γ is the ratio of specific heat of air;

[0258] S5.2, relative to the reference point, the angle of attack induced by the porous wall includes the lift interference and the support interference to the flow field, the lift effect of the flow field disturbance caused by the angle of attack interference is calculated, and the calculation formula is:

[0259]

[0260] Wherein, ω wm is the normal disturbance velocity of the test model and the porous wall in the flow field of the test section, ω m is the normal disturbance velocity of the test model in the free stream, ω ws is the normal disturbance velocity of the test model and the porous wall in the flow field of the test section, ω s is the normal disturbance velocity of the support in the free stream, α is the angle of attack, α m is the angle of attack induced by the test model, α s is the angle of attack induced by the support, is the normal disturbance of the flow field caused by the porous wall induced by the model, is the axial disturbance of the flow field caused by the porous wall induced by the support. and The calculation formula is:

[0261]

[0262] S5.3, relative to the far field flow, the calculation formula of the angle of attack induced by the porous wall is:

[0263]

[0264] Still taking the civil aircraft half model as an example, the influence of the hole wall on the lift disturbance factor of the model area flow field is studied for the ideal slotted wall differential form with the opening-closing ratio R=1%, 2%, 4%, 6%, and the slotted wall considering the viscous effect with the opening-closing ratio R=1%-18%. From Figure 4 the change law of the lift disturbance factor along the axis of the wind tunnel can be seen. The disturbance direction of the real wall test section and the ideal slotted wall differential form is opposite, and the lift disturbance factor of the slotted wall considering the viscous effect is between the real wall and the ideal slotted wall, and is closer to the real wall. The lift disturbance of the real wall test section is obviously stronger than that of the slotted wall test section. The ideal slotted wall differential form, with the increase of the opening-closing ratio, the disturbance degree gradually increases. The influence of the opening-closing ratio on the slotted wall considering the viscous effect is smaller than that of the ideal slotted wall differential form. Specific implementation two:

[0266] An electronic device includes a memory and a processor, the memory stores a computer program, and the processor executes the computer program to implement the steps of the test section subsonic flow field quality evaluation method.

[0267] The computer device of the present application can be a device including a processor and a memory, such as a single-chip microcomputer including a central processing unit. The processor is used to execute the computer program stored in the memory to implement the steps of the test section subsonic flow field quality evaluation method.

[0268] The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0269] The memory can mainly include a program storage area and a data storage area. The program storage area can store an operating system, at least one application program required for a function (such as a sound playing function, an image playing function, etc.), etc. The data storage area can store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash memory device, or other volatile solid-state memory device. Specific implementation three:

[0271] A computer readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the test section subsonic flow field quality evaluation method.

[0272] The computer readable storage medium of the present application can be any form of storage medium readable by the processor of the computer device, including but not limited to non-volatile memory, volatile memory, ferroelectric memory, etc., and the computer readable storage medium stores a computer program. When the processor of the computer device reads and executes the computer program stored in the memory, the steps of the test section subsonic flow field quality evaluation method described above can be implemented.

[0273] The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.

[0274] It should be noted that the relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations exist in any such actual relationship or order. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0275] Although the present application has been described above with reference to a specific embodiment, various modifications can be made thereto and equivalents can be substituted for elements thereof without departing from the scope of the present application. In particular, each feature disclosed in the specific embodiments of the present application can be combined with any other feature disclosed in the present specification, as long as there is no structural conflict. The combinations of these features are not exhaustively described in the present specification, which is only for the purpose of omitting the length and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method of assessing the quality of a subsonic flow field in a test section, the method comprising: The method comprises the following steps: ​ S1, using the improved Keller panel method to calculate the disturbance velocity basic solution of the subsonic flow field of the test section, and constructing a disturbance velocity database of the subsonic flow field of the test section; S2, using the singularity method to construct an expression of the test model; S3, according to the expression of the test model constructed in step S2, calculating the singularity strength of the lift effect of the test model; S4, according to the expression of the test model constructed in step S2 and the singularity strength of the lift effect of the test model obtained in step S3, calculating the singularity strength of the blockage effect of the test model; S5, using the singularity strength of the lift effect of the test model calculated in step S3 to calculate the lift effect of the model and the support, and using the singularity strength of the blockage effect of the test model calculated in step S4 to calculate the blockage effect of the model and the support, and the lift effect and the blockage effect together constitute the disturbance of the flow field of the test section gas permeable wall.

2. The method of evaluating the quality of a subsonic flow field in a test section according to claim 1, wherein: The specific implementation method of step S1 comprises the following steps: S1.1, the subsonic flow field of the test section comprises a solid wall, a free jet boundary, an open hole wall, a slot wall without viscous influence and a slot wall with viscous influence, and the boundary conditions of the subsonic flow field of the test section are set as: wherein C1 is a first boundary condition parameter, C2 is a second boundary condition parameter, C3 is a third boundary condition parameter, and C4 is a fourth boundary condition parameter, is the velocity potential of the flow field, x is the axial coordinate, and n is the normal coordinate. S1.2, the calculation formula of the total velocity potential of the gas permeable wall boundary is: φ = φ m + φ w where φm m is the total velocity potential of the model, m is the model, φw w is the total velocity potential of the porous wall, w is the porous wall; S1.3, the total velocity potential of the test model obtained in step S2 and the total velocity potential of the gas permeable wall satisfy the boundary conditions of the subsonic flow field of the test section in step S1.1, and then the calculation formula is obtained: S1.4, the air permeable wall is modeled according to the improved Keller panel method, a point source with a slope of σ' is arranged at each grid center of the air permeable wall, and a velocity potential function of the i-th row of grids of the air permeable wall is The expression is: wherein, is the velocity potential function at the center of the grid in the i-th row and j-th column of the permeable wall, σ' j is the slope of the point source at the center of the grid in the j-th column. and the velocity potential function of the center of the grid of the gas-permeable wall The calculation formula is: Wherein, the coordinates of the wall grid angle point of the gas permeable wall are (ξ, η, ζ), and B is the downstream boundary; S1.5, then according to the calculation formula of step S1.3 and step S1.4, the following formula is obtained: where a ij is the velocity potential function at the center of the grid is the negative of the calculated result that satisfies the boundary condition, is the velocity potential generated by the model at the i-th row grid i is the velocity potential generated by the model at the i-th row grid is the negative of the calculated result that satisfies the boundary condition; The disturbance velocity of the gas permeable wall to the subsonic flow field of the test section is calculated as: wherein k is any one of n, u w is the axial disturbance velocity of the subsonic flow field of the test section by the porous wall, v w is the lateral disturbance velocity of the subsonic flow field of the test section by the porous wall, ω w is the normal disturbance velocity of the subsonic flow field of the test section by the porous wall; By calculating the flow field disturbance velocity of the unit strength singularity of the model, the unit singularity test section subsonic flow field disturbance velocity database is constructed.

3. The method for evaluating the quality of a subsonic flow field in a test section according to claim 1 or 2, characterized in that: The specific implementation method of step S2 comprises the following steps: S2.1, Constructing the expressions for sources or sinks, for line dipoles, for the velocity potential of a unit source or sink The expression for the velocity potential of a unit source or sink is Wherein, (x, y, z) is the spatial position coordinates except for source or sink, (x0, y0, z0) is the spatial position coordinates of source or sink, and σ is the unit singularity strength; Velocity potential of a unit line dipole The expression for the velocity potential of a unit line dipole is ξ0=x0 η0=y0·cosθ-z0·sinθ ζ0=y0·sinθ+z0·cosθ Wherein, θ is the direction angle of the linear dipole; S2.2, using the singularity method to construct the expression of the test model, including the fuselage expression of the test model, the separated wake expression of the test model, the wing and tail expression of the test model; The fuselage expression of the test model is: σ k* = λ k · σ * , k = 1, 2,... 2μ λ k = -λ k-μ , k = μ + 1, μ + 2,... 2μ where σ k* is the body strength of the test model, λ k is the specific gravity coefficient, σ * is the unit singularity strength of the body using source or sink, μ is the number of body sources, and 2μ is the number of body sources or sinks; The separated wake expression of the test model is: σ k** = λ k · σ ** , k = 2μ + 1, 2μ + 2... ε where σ k** is the isolated wake strength of the test model, σ ** is the unit point strength of the isolated wake source or sink, and ε is the number of body sources or sinks and wake sources. The expression of the wing of the test model is, and the tail expression is: where σ d is the wing strength of the test model, Δs d is the wing span interval of the test model, λ d is the specific gravity coefficient of the wing of the test model, Γ d is the circulation of the wing of the test model, U ref is the velocity of the reference point of the flow field; σ t is the tail strength of the test model, Δs t is the tail span interval of the test model, λ t is the specific gravity coefficient of the tail of the test model, Γ t is the circulation of the tail of the test model; S2.3, the disturbance velocity of the test section subsonic flow field obtained in step S1 is decomposed according to the linear subsonic linear superposition principle and divided by the reference point velocity U of the flow field ref The calculation formula is: where σ is the singularity strength, σ k is the intensity of the kth singularity, u * (k) is the axial disturbance velocity at the kth point, v * (k) is the lateral disturbance velocity at the kth point, ω * (k) is the normal disturbance velocity at the kth point, is the intensity-normalized axial disturbance velocity at the kth point, is the intensity-normalized lateral disturbance velocity at the kth point, is the intensity-normalized normal disturbance velocity at the kth point.

4. The method of evaluating the quality of a subsonic flow field in a test section according to claim 3, wherein: The specific implementation method of step S3 comprises the following steps: S3.1, the lift and pitching moment of the test model includes the lift of the wing and tail, and the pitching moment of the wing and tail, wherein the calculation formula of the lift of the wing and tail is: where L is the lift of the wing and tail, L d (i) is the lift of the i-th segmented wing, L t (j) is the lift of the j-th segmented tail, n d is the number of segments of the wing, n t denotes the number of segments of the tail; The calculation formula of the pitching moment of the wing and tail is: where P is the pitching moment of the wing and tail, x mr is the x-coordinate of the moment reference point, x d (i) is the x-coordinate of the i-th segment wing lift action point, x t (j) is the x-coordinate of the j-th segment tail lift action point, P is the pitching moment; S3.2, according to the Kutta-Joukowski formula, the lift in step S3.1 is rewritten as: where C L is the lift coefficient of the test model, p is the air density, U is the wind speed, and c is the mean aerodynamic chord. The calculation formula of air density is: where M ref is the Mach number of the reference point, and ∈ is the choking factor, with an initial value of 0.

01. S3.3, the calculation formula of the standardized linear dipole strength is constructed as: S3.4, calculating the normalized line dipole strength of the wing and the normalized line dipole strength of the tail according to the expression of the wing, the expression of the tail of the test model and the normalized line dipole strength constructed in step S3.3: where σ d (i) is the wing strength of the i-th segment test model, σ t (j) is the tail strength of the j-th segment test model, σ d is the normalized line dipole strength of the wing, σ t is the normalized line dipole strength of the tail; S3.5, setting the parameters as follows: Where a1 is the specific gravity coefficient λ of the experimental model wing. d The sum of the wing span interval Δs of the experimental model d The product parameter, a2 is the specific gravity coefficient λ of the tail fin of the experimental model. t The sum of the tail fin span interval Δs of the experimental model t The product parameter, b1 is the specific gravity coefficient λ of the test model wing. d The sum of the products of the distance between the point of application of the lift force on the wing and the distance between the moment reference point and the wing span interval Δs of the test model. d The product parameter, b2 is the specific gravity coefficient λ of the tail fin of the experimental model. t The sum of the products of the distance between the tail fin lift application point and the moment reference point, and the tail fin span interval Δs of the experimental model. t The product parameters; Then the circulation of the wing of the test model and the circulation of the tail of the test model are calculated as follows: wherein p ref is the air density at the reference point; the clogging factor ∈ is obtained by iterative calculation, step S5 being recomputed after step S3 until the error of ∈ is less than 0.

001.

5. The method of evaluating the quality of a test section subsonic flow field according to claim 4, wherein: The specific implementation method of step S4 includes the following steps: S4.1, the calculated disturbance velocity of the porous wall is equal to the sum of the disturbance velocity of the lift effect on the porous wall and the disturbance velocity of the model blockage effect on the porous wall, and the calculation formula is: where δ is the test point on the porous wall, U e is the empty tunnel velocity, u t is the axial disturbance velocity generated by the test model and the support on the porous wall, u ts is the axial disturbance velocity generated by the support on the porous wall; S4.2, set the number of measuring points on the gas permeable wall to m, and solve σ by the least square fitting method * and σ ** , the calculation formula is: where A m×2 is the matrix of the sum of the products of the body and wake fraction coefficients and the normalized axial disturbance velocity, B m×1 is the vector of the result of subtracting the disturbance velocity generated by the lift effect on the porous wall from the measured disturbance velocity of the porous wall, X 2×1 is the vector of the unit singular point strength of the body source-sink and the wake source. where a δ,1 is the sum of the product of the specific gravity coefficient of the fuselage and the normalized axial disturbance velocity, a δ,2 is the sum of the product of the specific gravity coefficient of the wake and the normalized axial disturbance velocity, b k is the result of subtracting the disturbance velocity of the permeable wall generated by the lift effect from the measured permeable wall disturbance velocity.

6. The method of evaluating a quality of a subsonic flow field in a test section according to claim 5, wherein: The specific implementation method of step S5 includes the following steps: S5.1, the calculation formula of the blockage factor is: wherein ∈(v) is the total blockage factor of the model and the support, ∈ m (ψ) is the blockage factor of the test model at the position point in the flow field of the wind tunnel, ∈ s (ψ) is the blockage factor of the support at the position point in the flow field of the wind tunnel, ψ represents the position point in the flow field of the wind tunnel, u wm is the axial disturbance velocity generated by the test model and the permeable wall in the flow field of the test section, u m is the axial disturbance velocity generated by the test model in the free flow, u ws is the axial disturbance velocity generated by the support and the permeable wall in the flow field of the test section, u s is the axial disturbance velocity generated by the support in the free flow, is the axial disturbance velocity generated by the permeable wall in the flow field of the test section caused by the model, is the axial disturbance velocity generated by the permeable wall in the flow field of the test section caused by the support, and the calculation formula is: The blockage effect of the flow field disturbance caused by the Mach number interference is calculated, and the calculation formula is: where M ∞ is the Mach number at a far field, and γ is the specific heat ratio of air. S5.2, relative to the reference point, the flow angle induced by the porous wall includes the lift interference and the support interference on the flow field, the lift effect of the flow field disturbance caused by the flow angle interference is calculated, and the calculation formula is: where ω wm is the normal disturbance velocity of the test model and the permeable wall in the flow field of the test section, ω m is the normal disturbance velocity of the test model in the free stream, ω ws is the normal disturbance velocity of the support and the permeable wall in the flow field of the test section, ω s is the normal disturbance velocity of the support in the free stream, α is the flow angle, α m is the flow angle induced by the test model, α s is the flow angle induced by the support, is the normal disturbance of the permeable wall to the flow field caused by the model, is the axial disturbance of the permeable wall to the flow field caused by the support. and The calculation formula is: S5.3, relative to the far front flow, the calculation formula of the flow angle induced by the porous wall is:

7. An electronic device, characterized by The computer program is executed by the processor to realize the steps of the test section subsonic flow field quality evaluation method according to any one of claims 1-6.

8. A computer readable storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to realize the steps of the test section subsonic flow field quality evaluation method according to any one of claims 1-6.

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