A Wave Rider Effect Assessment Method Based on Wave Rider Factor

Abstract

This invention discloses a waverider effect evaluation method based on the waverider factor, comprising: obtaining the hypersonic shock wave flow field of the waverider; voxelizing the hypersonic shock wave flow field of the waverider to obtain the pressure gradient of each voxel; substituting the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, which is the shock surface in the flow field; removing noise from the shock surface in the flow field to obtain a denoised shock surface; smoothing the denoised shock surface using the Laplace algorithm to obtain the final flow field shock surface; projecting a preset leading edge line of the waverider onto the final flow field shock surface to obtain the leading edge surface and obtaining the leakage of the leading edge surface; and obtaining the waverider factor based on the leakage of the leading edge surface. This invention provides a quantitative waverider effect evaluation method to assess the impact of changes in the flight environment and shape on the waverider effect of the waverider.

Description

Technical Field

[0001] This invention belongs to the field of aerodynamic performance evaluation technology for hypersonic vehicles, and particularly relates to a wave-riding effect evaluation method based on wave-riding factor. Background Technology

[0002] Based on the hyperbolic characteristics of hypersonic inviscid flow, the aerodynamic performance of aircraft can be significantly improved, and waveriders are a typical shape that utilizes this property. Waveriders use attached shock waves to isolate high-pressure aerodynamics on the lower surface of the aircraft, preventing flow leakage and effectively overcoming the lift-drag barrier of hypersonic vehicles, resulting in a very high lift-drag ratio.

[0003] However, when applied to wide-speed-range aircraft, the waverider theory design method is only applicable to specific flight Mach numbers and angles of attack. Since the overall mission requirements often dictate changes in speed and angle of attack during flight, when deviating from the design angle of attack, the high-pressure portion of the lower surface leaks to the upper surface of the aircraft. Simultaneously, when the flight Mach number is lower than the design Mach number, shock wave detachment is more severe, pressure exchange between the upper and lower surfaces is stronger, and the pressure difference decreases, resulting in a more significant drop in lift-to-drag ratio. Therefore, maintaining a high lift-to-drag ratio while deviating from the design state requires careful consideration. Secondly, balancing low-speed performance requires... Modifying and compromising the shape characteristics of hypersonic aircraft, such as increasing wing area and optimizing low-speed airfoils, may weaken the "wave-riding" effect. Third, the theoretically designed wave-rider body needs engineering treatment, such as leading-edge passivation, upper surface bulge expansion, and vertical tail / stabilizer installation. Passivating the edges will increase the distance between the shock wave and the leading edge, increase the leakage of high-pressure gas from the lower surface to the upper surface, and reduce the lift-to-drag ratio of the wave-rider body in the design state. At the same time, the installation of wing rudders will also cause the shock wave to detach significantly, resulting in depressurization, thus failing to perfectly maintain the "wave-riding" characteristics.

[0004] Compared to traditional layouts, the lift-enhancing principle of waveriders relies on the attachment of shock waves to prevent high-pressure gas leakage from the lower surface to the upper surface. However, in practical engineering applications as described above, the shock wave's blocking effect is often weakened, inevitably undermining the theoretical waveriding characteristics. To reduce this detrimental effect, the urgent task is to quantitatively assess the waveriding characteristics, establishing evaluation criteria based on factors such as changes in shock wave shape and the amount of gas leakage from the lower surface to the upper surface. Research in these areas is scarce. Currently, common methods in the literature for evaluating waveriding characteristics or the effectiveness of waverider design methods primarily involve observing the attachment of the shock wave to the leading edge. The closer the shock wave is to the leading edge, the more pronounced the waveriding effect is considered, and the more effective the design method is believed to be. However, this subjective observation-based evaluation method is heavily influenced by human factors and is not suitable as a standard evaluation criterion. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a wave-riding effect evaluation method based on the wave-riding factor. This method provides a quantitative wave-riding effect evaluation method to assess the impact of changes in the flight environment and shape on the wave-riding effect of the wave-rider.

[0006] The objective of this invention is achieved through the following technical solution: a wave-riding effect evaluation method based on the wave-riding factor, comprising: obtaining the hypersonic shock wave flow field of the wave-rider; voxelizing the hypersonic shock wave flow field of the wave-rider to obtain the pressure gradient of each voxel; substituting the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, which is the shock surface in the flow field; removing noise from the shock surface in the flow field to obtain a denoised shock surface; smoothing the denoised shock surface using the Laplace algorithm to obtain the final flow field shock surface; projecting a preset leading edge line of the wave-rider onto the final flow field shock surface to obtain the leading edge surface and obtaining the leakage of the leading edge surface; and obtaining the wave-riding factor based on the leakage of the leading edge surface.

[0007] In the above-mentioned wave-riding effect evaluation method based on wave-riding factor, computational fluid dynamics is used to obtain the hypersonic shock wave flow field of the wave-riding body; wherein, the hypersonic shock wave flow field of the wave-riding body includes pressure p and Mach number Ma.

[0008] In the above wave-riding effect evaluation method based on wave-riding factor, the Lovely-Haimes algorithm formula is as follows:

[0009]

[0010] Among them, Ma n denoted as the normal Mach number, Ma is the Mach number, ▽p is the pressure gradient of each voxel, V is the local velocity, and a is the local speed of sound.

[0011] In the above-mentioned wave-riding effect evaluation method based on wave-riding factor, the isosurface is extracted using contour tracking method, moving cube method or octree-based isosurface extraction algorithm.

[0012] In the above wave-riding effect evaluation method based on the wave-riding factor, the formula for removing noise is:

[0013]

[0014] Where ▽p is the pressure gradient of each voxel, n is the unit normal vector of the measured shock surface, c is the first filter factor, η is the second filter factor, and |▽p max The maximum value of the pressure gradient for each voxel.

[0015] In the above-mentioned wave-riding effect evaluation method based on wave-riding factor, the leakage of the leading edge surface is obtained by: obtaining the flux of each triangular facet by multiplying the normal vector of the triangular facet of the leading edge surface with the velocity on the triangular facet; and integrating the flux of all triangular facets to obtain the leakage of the leading edge surface.

[0016] In the above wave-riding effect evaluation method based on the wave-riding factor, the flux of each triangular facet is obtained by the following formula:

[0017] flux = dot(v,n) * rho * area;

[0018] Where flux is the flux of each triangular facet, v is the velocity on the triangular facet, n is the normal vector of the triangular facet, dot() is the dot product, rho is the density of the triangular facet, and area is the area of ​​the triangular facet.

[0019] In the above wave-riding effect evaluation method based on the wave-riding factor, the wave-riding factor is obtained by the following formula:

[0020]

[0021] Among them, K w q is the waverider factor. l q represents the leakage at the leading edge. p For the reference flow rate, S p The projected area is the direction of flow.

[0022] In the above wave-riding effect evaluation method based on the wave-riding factor, the wave-riding factor K... w The closer a value is to 1, the stronger the aircraft's ability to "capture" shock waves and the better its wave-riding performance.

[0023] A wave-riding effect evaluation system based on wave-riding factor includes: a first module for obtaining the hypersonic shock wave flow field of the wave-rider; a second module for voxelizing the hypersonic shock wave flow field of the wave-rider to obtain the pressure gradient of each voxel; a third module for substituting the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, which is the shock surface in the flow field; a fourth module for removing noise from the shock surface in the flow field to obtain a denoised shock surface; a fifth module for smoothing the denoised shock surface using the Laplace algorithm to obtain the final flow field shock surface; a sixth module for projecting a preset leading edge line of the wave-rider onto the final flow field shock surface to obtain the leading edge surface and obtain the leakage of the leading edge surface; and a seventh module for obtaining the wave-riding factor based on the leakage of the leading edge surface.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) This invention can eliminate the influence of subjective factors by defining the waverider factor and quantitatively evaluate the waverider effect when a waverider or conventional layout aircraft is flying at supersonic speed.

[0026] (2) The quantitative assessment of the wave-riding effect of this invention can guide the layout design of hypersonic vehicles and avoid the destruction of the wave-riding effect by engineering treatment as much as possible.

[0027] (3) The quantitative assessment of the waverider effect in this invention helps to redefine the definition and scope of the waverider. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0029] Figure 1 This is a shock surface extraction diagram of a single swept-back waverider flow field provided in an embodiment of the present invention;

[0030] Figure 2 This is a magnified view of the leading edge surface of the single swept waverider provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the curved leading-edge waverider shape provided in an embodiment of the present invention;

[0032] Figure 4(a) is a schematic diagram showing the variation of the waverider factor of the curved leading edge waverider with different Mach numbers and angle of attack according to the embodiment of the present invention;

[0033] Figure 4(b) is a schematic diagram showing the variation of the waverider factor of the curved leading edge waverider with different Mach numbers and angle of attack according to the embodiment of the present invention;

[0034] Figure 5(a) is a top view of a single swept waverider half-mode with different swept angles provided in an embodiment of the present invention;

[0035] Figure 5(b) is a front view of a single swept waverider half-model with different swept angles provided in an embodiment of the present invention;

[0036] Figure 6(a) is a schematic diagram of the leakage amount with the angle of attack at different sweep angles provided in the embodiment of the present invention;

[0037] Figure 6(b) is a schematic diagram of the variation of wave-riding factors with angle of attack for different sweep angles provided in the embodiments of the present invention;

[0038] Figure 7 This is a flowchart of the wave-riding effect evaluation method based on the wave-riding factor provided in the embodiments of the present invention. Detailed Implementation

[0039] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Figure 7 This is a flowchart of the wave-riding effect evaluation method based on the wave-riding factor provided in an embodiment of the present invention. Figure 7 As shown, this embodiment provides a wave-riding effect evaluation method based on the wave-riding factor. The method includes: obtaining the hypersonic shock wave flow field of the wave-rider; voxelizing the hypersonic shock wave flow field of the wave-rider to obtain the pressure gradient of each voxel; substituting the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, which is the shock surface in the flow field; removing noise from the shock surface in the flow field to obtain the denoised shock surface; smoothing the denoised shock surface using the Laplace algorithm to obtain the final flow field shock surface; projecting the preset leading edge line of the wave-rider onto the final flow field shock surface to obtain the leading edge surface and obtaining the leakage of the leading edge surface; and obtaining the wave-riding factor based on the leakage of the leading edge surface.

[0041] The hypersonic shock wave flow field of the waverider was obtained using computational fluid dynamics methods; the hypersonic shock wave flow field of the waverider includes pressure p and Mach number Ma.

[0042] The Lovely-Haimes algorithm formula is:

[0043]

[0044] Among them, Ma n denoted as the normal Mach number, Ma is the Mach number, ▽p is the pressure gradient of each voxel, V is the local velocity, and a is the local speed of sound.

[0045] The isosurface is extracted using contour tracking, moving cube method, or octree-based isosurface extraction algorithm.

[0046] The formula for noise removal is:

[0047]

[0048] Where ▽p is the pressure gradient of each voxel, n is the unit normal vector of the measured shock surface, c is the first filter factor, η is the second filter factor, and |▽pmax The maximum value of the pressure gradient for each voxel.

[0049] The leakage at the leading edge is obtained by: taking the dot product of the normal vector of the triangular facet of the leading edge and the velocity on the triangular facet to obtain the flux of each triangular facet; and integrating the flux of all triangular facets to obtain the leakage at the leading edge.

[0050] The flux of each triangular facet is obtained by the following formula:

[0051] flux = dot(v,n) * rho * area;

[0052] Where flux is the flux of each triangular facet, v is the velocity on the triangular facet, n is the normal vector of the triangular facet, dot() is the dot product, rho is the density of the triangular facet, and area is the area of ​​the triangular facet.

[0053] The waverider factor is obtained by the following formula:

[0054]

[0055] Among them, K w q is the waverider factor. l q represents the leakage at the leading edge. p For the reference flow rate, S p The projected area is the direction of flow.

[0056] Waverider factor K w The closer a value is to 1, the stronger the aircraft's ability to "capture" shock waves and the better its wave-riding performance.

[0057] Specifically, the method includes the following steps:

[0058] Step 1: Obtain the hypersonic shock wave flow field of the waverider using computational fluid dynamics (CFD) technology. The flow field result file contains basic information such as pressure p and Mach number Ma.

[0059] Step 2: Voxelize the flow field results obtained in Step 1 and calculate the pressure gradient for each voxel;

[0060] Step 3: Based on the pressure gradient obtained in Step 2, substitute it into the Lovely-Haimes algorithm formula: Extracting the isosurfaces in the flow field is equivalent to extracting the shock wave surface in the flow field. In the formula, a is the local sound velocity and V is the local velocity. The isosurfaces can be extracted using contour tracking, moving cube method, and octree-based isosurface extraction algorithm, etc.

[0061] Step 4: Based on the expression used: The filtering method is used to remove the noise from the shock surface obtained in step three, where n is the unit normal vector of the shock surface being measured. This method allows the degree of noise filtering to be controlled by manually specifying η. For other small noises, flooding and DBSCAN can be used for removal.

[0062] Step 5: Smooth the denoised shock surface obtained in Step 4 using the Laplace algorithm to obtain the final flow field shock surface;

[0063] Step Six: Load the specified waverider leading edge line into the flow field. Starting from the leading edge line, trace the shock surface with the normal vector of the object surface as the direction. Calculate the distance from the object surface to the shock surface by traversing the shock surface using a ray with the normal vector of the object surface as the direction. Construct a mesh and points by bisecting the distance and direction. Interpolate at each point to generate the final leading edge surface. The flux of all triangular facets on the leading edge surface is integrated using the dot product of the normal vector of the facet and the velocity on that facet: flux = dot(v,n)*rho*area, to obtain the leakage q at the lower surface of the waverider. l Where rho is the density on the surface and area is the area of ​​the surface;

[0064] Step 7: Calculate the leakage amount q obtained in Step 6. l Substituting into the definition of the waverider factor: Where S p Let q be the projected area of ​​the flow direction. p For flow direction reference flow rate; wave rider factor K w The closer the value is to 1, the stronger the aircraft's ability to "capture" shock waves and the better its wave-riding performance.

[0065] Step 8: Based on the wave-riding effect evaluation method established in Steps 1 to 7, the wave-riding effect of different given wave-riding body models is evaluated, and the following patterns are obtained: The wave-riding factor decreases to a certain extent with the increase of the angle of attack, corresponding to an increase in the overflow of the lower surface and a weakening of the wave-riding effect; When the incoming Mach number is significantly higher than the design state, the leakage and the change of the wave-riding factor with the angle of attack are significantly weakened, and the wave-riding effect is enhanced; conversely, the wave-riding factor decreases and the wave-riding effect weakens; As the height increases, the wave-riding factor decreases and the wave-riding effect weakens; The larger the sweep angle, the lower the shock wave adhesion of the leading edge, the greater the leakage, and the smaller the corresponding wave-riding factor.

[0066] The principle of identifying and extracting the shock surface is to treat a typical oblique shock wave as a normal shock wave superimposed on a uniform flow. The normal Mach number can be obtained from the pressure distribution, and the shock surface can be extracted. The waverider factor is defined as the leakage between the leading edge of the waverider and the attached shock wave in a supersonic shock wave field, serving as a criterion for evaluating the waverider effect. For this type of supersonic shock wave field, computational fluid dynamics combined with adaptive grids is used to calculate the flow field and evaluate the aerodynamic performance of the waverider. The Lovely-Hamies algorithm is used to identify and extract the shock surface in this type of supersonic shock wave field.

[0067] The flux between the front edge of the statistical shock wave and the object surface is approximated as the gas leakage from the lower surface to the upper surface, serving as a quantitative evaluation standard for measuring the wave-riding effect.

[0068] The leakage between the shock wave and the leading edge of the waverider is determined by projecting the leading edge profile onto the shock surface, constructing a grid of points based on distance and direction, interpolating at each point to generate the final leading edge surface, and then calculating the leakage. The ratio of the leakage to the projected flow rate on the lower surface of the waverider can be used as a criterion for evaluating the waveriding performance of the waverider; the smaller the ratio, the larger the waveriding factor and the stronger the waveriding performance.

[0069] The flow field was calculated using CFD combined with an adaptive grid, and the aerodynamic performance was evaluated. The Lovely-Hamies algorithm was used to identify and extract the shock wave surface. The flux between the leading edge of the shock wave and the object surface was statistically approximated as the gas leakage from the lower surface to the upper surface. The wave-riding factor was defined as a quantitative evaluation standard for measuring the "wave-riding effect".

[0070] <1> Hypersonic shock wave flow field acquisition

[0071] The finite volume method is used to solve the three-dimensional compressible Navier-Stokes equations. Inviscid flux is calculated using the Roe scheme, and a weighted Green-Gauss formula reconstruction method is employed to achieve second-order spatial accuracy. An improved Barth limiter is selected as the gradient limiter to eliminate numerical overshoot and oscillations near computational breaks. Viscous flux is calculated using a second-order central scheme. The turbulence model adopts the widely used Menter SST k-ω two-equation model in engineering, employing a second-order accurate two-time-step method in the time direction, with implicit LU-SGS solution. A partitioned structured mesh is used. To improve spatial resolution and capture flow characteristics, the mesh is refined in the shock wave region.

[0072] <2> Extracting shock surface

[0073] The Lovely-Hamies algorithm identifies and extracts shock surfaces by treating a typical oblique shock wave as a normal shock wave superimposed on a uniform flow. The normal flow characteristics before and after the oblique shock wave satisfy the normal shock wave relationship, and the shock wave normal is perpendicular to the local pressure gradient. Therefore, the normal Mach number can be obtained from the pressure distribution, and the isosurface of the unit normal Mach number represents the detected shock surface. Thus, the mathematical expression for static shock wave detection based on the normal Mach number in the Lovely-Hamies algorithm is:

[0074]

[0075] In the formula, Ma is the Mach number vector in the local velocity direction, a is the local sound speed, and V is the local velocity. For transient shock wave detection, the motion of the shock wave must be considered, and the condition then becomes:

[0076]

[0077] Where dp / dt is the time derivative of pressure, which can be calculated based on the spatial variation of the state variable:

[0078]

[0079] H is the static enthalpy. In practical applications, the normal Mach number is calculated by projecting the velocity along the pressure gradient direction. Due to numerical errors in interpolation, a small, non-directional pressure gradient may be calculated in a uniform flow region, leading to an inaccurate Mach number. n Randomization of the distribution and erroneous shock wave detection. Filtering is a common strategy to avoid such spurious shock waves. Typically, filtering methods introduce filter factors c and η, and ensure that the local pressure gradient meets certain requirements.

[0080]

[0081] In the formula, n is the unit normal vector of the measured shock wave surface.

[0082] The process of generating shock waves using Lovely-Hamies mainly consists of four steps:

[0083] a) Calculate the eigenvalues ​​of the pressure gradient

[0084] According to the expression (1) of the Lovely-Haimes algorithm, the eigenvalues ​​of the pressure gradient need to be calculated. In the calculation process, the flow field is first voxelized, and then the pressure gradient is calculated for each voxel.

[0085] b) Isosurface extraction based on eigenvalues

[0086] After calculating the pressure gradient, the isosurface is extracted according to equation (1). The isosurface can be extracted using contour tracking, moving cube method, and octree-based isosurface extraction algorithm, etc.

[0087] c) Screening isosurfaces to remove noise.

[0088] For most noise, filtering methods can be used to filter out most of the noise by applying certain constraints. According to expression (4), η is manually specified to control the degree of noise filtering; for the remaining minor noise, flooding and DBSCAN methods can be used for removal.

[0089] d) Smoothing the shock wave surface

[0090] Smoothing can improve system performance or image quality. The Laplacian algorithm can be used to smooth the shock surface.

[0091] Figure 1 The shock surface extracted by a single swept wave-riding body with incoming flow Ma = 6 and angle of attack α = 8° is given.

[0092] <3> Statistical analysis of lower surface leakage

[0093] The specified leading edge line is read. Starting from the leading edge line, the shock surface is traced with the normal vector of the object surface as the direction. The distance from the object surface to the shock surface is calculated by traversing the shock surface with the normal vector of the object surface as the direction. The mesh and points are constructed by bisecting the distance and direction. Interpolation is performed on each point to generate the final leading edge surface. The flux on the leading edge surface is the leakage of the lower surface of the waverider.

[0094] The flux calculation process involves multiplying the normal vector of the triangular facet of the leading edge by the velocity on that face, then multiplying by the density on that face and the area of ​​the facet. The specific formula is:

[0095] flux = dot(v,n)*rho*area (5)

[0096] Where rho is the density on the surface and area is the area of ​​the surface patch. The corresponding flux can be calculated from equation (5).

[0097] Figure 2 The leading edge surface for extraction using a single swept wave volume is given.

[0098] <4> Define waverider factor

[0099] Based on the flow field, the shock wave surface is extracted, and the following parameters are defined:

[0100] a) Overflow surface S of (Overflow Surface)

[0101] The area (dimensioned) of the plane formed between the leading edge profile and its projection onto the detached shock surface;

[0102] b) Leakage amount q l (Leak Flux)

[0103] The normal flow rate of the overflow surface (direction needs to be considered, and the upward direction of the normal is conventionally positive) represents the amount of airflow flowing from the lower surface of the aircraft to the upper surface, and the flow rate (with dimensions).

[0104] c) Flow direction to projection surface S p (Projection surface)

[0105] The lower surface of the aircraft is projected into the far field along the flow direction, and its area (with dimensions) is given.

[0106] d) Flow direction reference flow rate q p (Projection Flux)

[0107] That is, the flow rate (velocity * density * area) of the projected surface, where the flow rate (with dimensions) is...

[0108] The waverider factor is defined using a piecewise function:

[0109]

[0110] Here K w The closer a value is to 1, the stronger the aircraft's ability to "capture" shock waves and the better its wave-riding performance. Currently, because shock wave identification is more accurate at hypersonic speeds, this definition is mainly applied to hypersonic conditions.

[0111] <5> Waverider effect assessment

[0112] a) The influence of flight environment on wave-riding effect

[0113] The investigation Figure 3 The diagram shows the leakage and wave-riding factor of a curved leading-edge waverider with a design state of Ma=8 and height H=30km under different Mach numbers and heights, varying with the angle of attack. The results are shown in Figures 4(a) and 4(b). It can be seen that the wave-riding factor decreases to some extent with increasing angle of attack, corresponding to an increase in the overflow at the lower surface and a weakening of the wave-riding effect. When the incoming Mach number is significantly higher than the design state, the variation of leakage and wave-riding factor with the angle of attack is significantly reduced, and the wave-riding effect is enhanced; conversely, the wave-riding factor decreases, and the wave-riding effect weakens. With increasing height, the wave-riding factor decreases, and the wave-riding effect weakens.

[0114] b) The effect of shape changes on the wave-riding effect

[0115] Figures 5(a) and 5(b) show single-sweep waveriders with different sweep angles, designed at Ma=6 and height H=30km, while maintaining consistent volume ratios across all shapes (the volume ratio calculation formula is τ=V). 2 / 3 / S, where V is the volume of the waverider and S is the projected area of ​​the top view). The results are shown in Figures 6(a) and 6(b). It can be seen that the size of the sweep angle has a significant impact on the adhesion strength of the leading edge shock wave. The larger the sweep angle, the lower the adhesion of the leading edge shock wave, the greater the leakage, and the smaller the corresponding waverider factor.

[0116] This embodiment also provides a wave-riding effect evaluation system based on the wave-riding factor. The system includes: a first module for obtaining the hypersonic shock wave flow field of the wave-rider; a second module for voxelizing the hypersonic shock wave flow field of the wave-rider to obtain the pressure gradient of each voxel; a third module for substituting the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, which is the shock surface in the flow field; a fourth module for removing noise from the shock surface in the flow field to obtain a denoised shock surface; a fifth module for smoothing the denoised shock surface using the Laplace algorithm to obtain the final flow field shock surface; a sixth module for projecting a preset leading edge line of the wave-rider onto the final flow field shock surface to obtain the leading edge surface and obtain the leakage of the leading edge surface; and a seventh module for obtaining the wave-riding factor based on the leakage of the leading edge surface.

[0117] This embodiment identifies and extracts the shock wave shape, calculates the gas leakage from the lower surface to the upper surface, defines the wave-riding factor, and then establishes a mathematical model to evaluate the "wave-riding" effect. It evaluates the impact of changes in the flight environment and shape on the wave-riding effect of the wave-rider. The results show that the leakage on the lower surface increases with the angle of attack, the overall change in the wave-riding factor is relatively small, and the wave-riding effect is obvious under different angles of attack in hypersonic states. Below the design Mach number, the leakage on the lower surface of the wave-rider increases, the wave-riding factor decreases, and the wave-riding effect weakens. The larger the sweep angle, the greater the leakage, the smaller the corresponding wave-riding factor, and the weaker the wave-riding effect.

[0118] This embodiment, by defining a waverider factor, can eliminate the influence of subjective factors and quantitatively evaluate the waverider effect during supersonic flight of a waverider or conventional layout aircraft. The quantitative evaluation of the waverider effect in this embodiment can guide the layout design of hypersonic aircraft and minimize the damage to the waverider effect caused by engineering treatments. The quantitative evaluation of the waverider effect in this embodiment helps to redefine the definition and scope of the waverider.

[0119] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for evaluating the wave-riding effect based on the wave-riding factor, characterized in that The application relates to a method for obtaining a wave-riding hypersonic shock wave flow field. The wave-riding hypersonic shock wave flow field is voxelized to obtain the pressure gradient of each voxel. The pressure gradient of each voxel is brought into a Lovely-Haimes algorithm formula to extract an isosurface in the flow field, which is a shock wave surface in the flow field. The shock wave surface in the flow field is denoised to obtain a denoised shock wave surface. The denoised shock wave surface is smoothed by using a Laplace algorithm to obtain a final flow field shock wave surface. A preset wave-riding body leading edge line is projected onto the final flow field shock wave surface to obtain a leading edge surface, and the leakage of the leading edge surface is obtained. A wave-riding factor is obtained according to the leakage of the leading edge surface. The leakage of the leading edge surface is obtained by: The flux of each triangular facet is obtained by the dot product of the normal vector of the triangular facet and the velocity on the triangular facet. The fluxes of all the triangular facets are integrated to obtain the leakage of the leading edge surface. The flux of each triangular facet is obtained by the following formula: flux = dot (v, n) * rho * area. The wave-riding factor is obtained by the following formula: The wave-riding hypersonic shock wave flow field is obtained by using a computational fluid dynamics method, wherein the wave-riding hypersonic shock wave flow field comprises pressure p and Mach number Ma. The Lovely-Haimes algorithm formula is: where K w is the wave multiplier, q l is the leakage of the leading edge, q p is the flow reference flow, S p is the flow projected area.

2. The wave multiplication effect evaluation method based on wave multiplication factor according to claim 1, characterized in that: The isosurface extraction adopts a contour tracking method, a moving cube method or an isosurface extraction algorithm based on an octree.

3. The wave multiplication effect evaluation method based on wave multiplication factor according to claim 1, characterized in that: The denoising formula is: where Ma n is the normal Mach number, Ma is the Mach number, is the pressure gradient for each voxel, V is the local velocity, and a is the local sound speed.

4. The wave multiplication effect evaluation method based on wave multiplication factor according to claim 1, characterized in that: The application further relates to a device for obtaining a wave-riding hypersonic shock wave flow field.

5. The wave multiplication effect evaluation method based on wave multiplication factor according to claim 1, characterized in that: The first module is used for obtaining a wave-riding hypersonic shock wave flow field. wherein, is the pressure gradient for each voxel, n is the measured shock front unit normal vector, c is a first filter factor, η is a second filter factor, is the maximum value of the pressure gradient for each voxel.

6. The wave multiplication effect evaluation method based on wave multiplication factor according to claim 1, characterized in that: Wave-riding factor K w The closer to 1, the stronger the vehicle's "capture" ability of the shock wave, the better the wave-riding performance.

7. A wave multiplication effect evaluation system based on a wave multiplication factor, characterized by The second module is used for voxelizing the wave-riding hypersonic shock wave flow field to obtain the pressure gradient of each voxel. The third module is used for bringing the pressure gradient of each voxel into a Lovely-Haimes algorithm formula to extract an isosurface in the flow field, which is a shock wave surface in the flow field. The fourth module is used for denoising the shock wave surface in the flow field to obtain a denoised shock wave surface. The fifth module is used for smoothing the denoised shock wave surface by using a Laplace algorithm to obtain a final flow field shock wave surface. The sixth module is used for projecting a preset wave-riding body leading edge line onto the final flow field shock wave surface to obtain a leading edge surface, and obtaining the leakage of the leading edge surface. The seventh module is used for obtaining a wave-riding factor according to the leakage of the leading edge surface. The leakage of the leading edge surface is obtained by: The flux of each triangular facet is obtained by the dot product of the normal vector of the triangular facet and the velocity on the triangular facet. The fluxes of all the triangular facets are integrated to obtain the leakage of the leading edge surface. The flux of each triangular facet is obtained by the following formula: flux = dot (v, n) * rho * area. The wave-riding factor is obtained by the following formula: ​ ​ ​ where K w is the wave multiplier, q l is the leakage of the leading edge, q p is the flow reference flow, S p is the flow projection area.

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