Waverider effect evaluation method based on waverider factors

Abstract

The invention discloses a waverider effect evaluation method based on waverider factors. The waverider effect evaluation method comprises the steps that a waverider hypersonic shock wave flow field is obtained; voxelization is carried out on the wave rider hypersonic shock wave flow field, and the pressure gradient of each voxel is obtained; substituting the pressure gradient of each voxel into a Lovely-Haimes algorithm formula to extract a contour surface in the flow field, namely a shock wave surface in the flow field; removing noise from the shock wave surface in the flow field to obtain a denoised shock wave surface; fairing the denoised shock wave surface by adopting a Laplace algorithm to obtain a final flow field shock wave surface; projecting a preset wave rider front edge line to the final flow field shock wave surface to obtain a front edge surface, and obtaining the leakage rate of the front edge surface; and obtaining a waverider factor according to the leakage rate of the front edge surface. The invention provides a quantitative waverider effect evaluation method which is used for evaluating the influence of flight environment change and appearance change on the waverider effect of the waverider.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerodynamic performance evaluation of hypersonic aircraft, and in particular relates to a waverider effect evaluation method based on a waverider factor. Background Art

[0002] According to the hyperbolic characteristics of hypersonic inviscid flow, the aerodynamic performance of the aircraft can be greatly improved, and the waverider is a typical shape that utilizes this characteristic. The waverider separates the high-pressure aerodynamics on the lower surface of the aircraft by attaching shock waves to prevent flow leakage, effectively breaking through the lift-drag barrier of the hypersonic aircraft and having a very high lift-drag ratio.

[0003] However, when applied to wide-speed range aircraft, since the waverider theory design method is only for specific flight Mach numbers and angles of attack, and according to the needs of the overall mission, the flight process often faces changes in speed and angle of attack. When the design angle of attack is deviated, the high-pressure part of the lower surface leaks to the upper surface of the aircraft. At the same time, when the flight Mach number is less than the design Mach number, the shock wave separation is more serious, the pressure exchange between the upper and lower surfaces is stronger, and the pressure difference is reduced, which makes the lift-to-drag ratio drop more obviously. Therefore, how to maintain the "waverider" effect and high lift-to-drag ratio that deviates from the design state needs to be considered; secondly, taking into account the low-speed performance requires Certain modifications and compromises to the hypersonic shape features, such as increasing the wing area and optimizing the low-speed airfoil, may lead to a weakening of the "waverider" effect; thirdly, the theoretically designed waverider requires engineering treatment, such as leading edge passivation, upper surface bulge expansion, vertical tail / stabilizer installation, etc. After the edge is passivated, the distance between the shock wave and the leading edge will become larger, the leakage of high-pressure gas from the lower surface to the upper surface will increase, and the lift-to-drag ratio of the waverider under the design state will be reduced. At the same time, the installation of the rudder will also cause the shock wave to detach from the body and cause pressure relief, making it impossible to perfectly maintain the "waverider" characteristics.

[0004] Compared with the traditional layout, the lift-increasing principle of the waverider is to attach shock waves to prevent the leakage of high-pressure airflow from the lower surface to the upper surface. However, in the actual engineering applications mentioned above, the blocking effect of the shock wave is often weakened, which will inevitably destroy the theoretical "waverider" characteristics. If you want to reduce the destructive effect, it is imperative to quantitatively evaluate the "waverider" characteristics and establish evaluation criteria based on the changes in the shock wave shape and the amount of gas leakage from the lower surface to the lower surface. There are very few studies in these areas. The common way to evaluate the effectiveness of the "waverider" characteristics or waverider design methods in the current literature is to observe the attachment of the shock wave to the leading edge line. The closer the shock wave is to the leading edge, the more obvious the waverider effect is, and the design method is considered to be effective. However, this subjective observation evaluation method is greatly affected by human factors and is not suitable as a set of standard evaluation criteria. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a waverider effect evaluation method based on a waverider factor, to provide a quantitative waverider effect evaluation method, and to evaluate the influence of flight environment changes and appearance changes on the waverider effect of a waverider body.

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

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

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

[0009]

[0010] Among them, Ma n is 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 sound speed.

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

[0012] In the above-mentioned 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 wave surface, c is the first filter factor, η is the second filter factor, |▽p max is the maximum value of the pressure gradient for each voxel.

[0015] In the above-mentioned waverider effect evaluation method based on the waverider factor, the leakage amount of the leading edge surface is obtained, including: obtaining the flux of each triangle patch according to the dot product of the normal vector of the triangle patch of the leading edge surface and the velocity on the triangle patch; integrating the flux of all triangle patches to obtain the leakage amount of the leading edge surface.

[0016] In the above waverider effect evaluation method based on the waverider factor, the flux of each triangle is obtained by the following formula:

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

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

[0019] In the above-mentioned 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 is the multiplication factor, q l is the leakage of the leading edge, q p is the reference flow rate, S p is the flow projection area.

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

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

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

[0025] (1) The present invention can eliminate the influence of subjective factors by defining the waverider factor, and quantitatively evaluate the waverider effect of a waverider or a conventional layout aircraft during supersonic flight;

[0026] (2) The quantitative evaluation of the waverider effect of the present invention can guide the layout design of hypersonic aircraft and avoid the damage of the waverider effect by engineering treatment as much as possible;

[0027] (3) The quantitative evaluation of the waverider effect of the present invention helps to redefine the definition and scope of the waverider. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0029] Figure 1 It is a shock wave surface extraction diagram of a single swept waverider flow field provided by an embodiment of the present invention;

[0030] Figure 2 It is a partial enlarged view of the leading edge surface extracted from a single swept waverider provided in an embodiment of the present invention;

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

[0032] FIG4( a ) is a schematic diagram showing how the waverider factor of a curved leading edge waverider according to an embodiment of the present invention varies with the angle of attack at different Mach numbers;

[0033] FIG4( b ) is a schematic diagram showing how the waverider factor of a curved leading edge waverider according to an embodiment of the present invention varies with the angle of attack at different Mach numbers;

[0034] FIG5( a ) is a top view of a single-swept waverider half-mold with different sweep angles provided by an embodiment of the present invention;

[0035] FIG5( b ) is a front view of a single-swept waverider half-mold with different sweep angles provided by an embodiment of the present invention;

[0036] FIG6( a ) is a schematic diagram of a curve showing the variation of leakage at different sweep angles with angle of attack provided by an embodiment of the present invention;

[0037] FIG6( b ) is a schematic diagram of a curve showing how the wave multiplier factors for different sweep angles vary with the angle of attack provided by an embodiment of the present invention;

[0038] Figure 7 It is a flow chart of a waverider effect evaluation method based on waverider factors provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] Figure 7 : is a flow chart of a method for evaluating a wave-riding effect based on a wave-riding factor provided by an embodiment of the present invention. Figure 7 As shown, this embodiment provides a waverider effect evaluation method based on a waverider factor, the method comprising: obtaining a waverider hypersonic shock wave flow field; voxelizing the waverider hypersonic shock wave flow field to obtain a pressure gradient of each voxel; subjecting the pressure gradient of each voxel to a Lovely-Haimes algorithm formula to extract an isosurface in the flow field, that is, a shock wave surface in the flow field; removing noise from the shock wave surface in the flow field to obtain a denoised shock wave surface; smoothing the denoised shock wave surface using a Laplace algorithm to obtain a final flow field shock wave surface; projecting a preset waverider leading edge line onto the final flow field shock wave surface to obtain a leading edge surface, and obtaining a leakage amount of the leading edge surface; and obtaining a waverider factor according to the leakage amount of the leading edge surface.

[0041] The computational fluid dynamics method is used to obtain the hypersonic shock wave flow field of the waverider; wherein 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 is 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 sound speed.

[0045] The isosurface is extracted by using contour tracing method, marching cube method or octree-based isosurface extraction algorithm.

[0046] The formula for removing noise is:

[0047]

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

[0049] Obtaining the leakage of the leading edge surface includes: obtaining the flux of each triangle surface according to the dot product of the normal vector of the triangle surface of the leading edge surface and the velocity on the triangle surface; and integrating the flux of all triangle surfaces to obtain the leakage of the leading edge surface.

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

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

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

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

[0054]

[0055] Among them, K w is the multiplication factor, q l is the leakage of the leading edge, q p is the reference flow rate, S p is the flow projection area.

[0056] Multiplier factor K w The closer it is to 1, the stronger the vehicle's ability to "capture" shock waves and the better the waveriding performance.

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

[0058] Step 1: Use computational fluid dynamics (CFD) technology to obtain the hypersonic shock wave flow field of the waverider. 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 of each voxel;

[0060] Step 3: Based on the pressure gradient obtained in step 2, substitute the Lovely-Haimes algorithm formula: Extract the isosurface in the flow field, that is, the shock wave surface in the flow field, where a is the local sound velocity and V is the local velocity. The isosurface can be extracted by contour tracking method, moving cube method and isosurface extraction algorithm based on octree, etc.

[0061] Step 4: According to the adopted expression: The filtering method is used to remove the shock wave surface noise obtained in step 3, where n is the unit normal vector of the measured shock wave surface. This method can manually specify η to control the degree of noise screening. For the remaining small noise, the flooding method and DBSCAN can be used to remove it;

[0062] Step 5: The de-noised shock wave surface obtained in step 4 is smoothed using the Laplace algorithm to obtain the final flow field shock wave surface;

[0063] Step 6: Load the specified waverider leading edge line in the flow field, take the leading edge line as the starting point, and track the shock wave surface with the normal vector of the object surface as the direction. Calculate the distance from the object surface to the shock wave surface by passing the ray with the normal vector of the object surface as the direction through the shock wave surface, and construct the grid and points by bisecting the distance and direction. Interpolate each point and generate the final leading edge surface. According to the dot product of the normal vector of the triangular patch of the leading edge surface and the velocity on its surface: flux = dot (v, n) * rho * area, integrate all the patch fluxes to get the leakage q of the lower surface of the waverider. l , where rho is the density on the surface and area is the area of ​​the patch;

[0064] Step 7: The leakage volume q obtained in step 6 l Substitute the multiplier factor definition formula: Where S p is the flow projection area, q p is the reference flow rate; the multiplier factor K w The closer it is to 1, the stronger the aircraft's ability to "capture" shock waves and the better its wave-riding performance;

[0065] Step 8: According to the waverider effect evaluation method based on the waverider factor established in steps 1 to 7, the waverider effects of given different waverider body models are evaluated, and the following rules are obtained: the waverider factor decreases with the increase of the angle of attack, the corresponding lower surface overflow increases, and the waverider effect weakens; when the incoming flow Mach number is significantly higher than the design state, the leakage amount and the waverider factor change with the angle of attack significantly weakened, and the waverider effect is enhanced, otherwise the waverider factor decreases and the waverider effect weakens; as the height increases, the waverider factor decreases and the waverider effect weakens; the larger the sweep angle, the lower the shock wave adhesion of the leading edge, the larger the leakage, and the smaller the corresponding waverider factor.

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

[0067] The flux between the front edge of the shock wave and the object surface is approximately the gas leakage from the lower surface to the upper surface, which is used as a quantitative evaluation criterion to measure the waverider effect.

[0068] The leakage between the shock wave and the leading edge of the waverider is projected onto the shock wave surface through the leading edge profile, and the grid and points are constructed by bisecting the distance and direction. Each point is interpolated and the final leading edge surface is generated to count 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 judging the waverider's waveriding performance. The smaller the ratio, the larger the waveriding factor and the stronger the waveriding performance.

[0069] CFD combined with adaptive grids is used to calculate the flow field and evaluate the aerodynamic performance. The Lovely-Hamies algorithm is used to identify and extract the shock wave surface. The flux between the front edge of the shock wave and the object surface is approximated as the gas leakage from the lower surface to the upper surface, and the waverider factor is defined as a quantitative evaluation standard to measure the "waverider 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. The inviscid flux is calculated using the Roe format. The weighted Green-Gaussian formula reconstruction method obtains the second-order accuracy in space. The gradient limiter selects the improved Barth limiter to eliminate the numerical overshoot and oscillation near the discontinuity in the calculation. The viscous flux is calculated using the second-order central format. The turbulence model uses the Menter SST k-ω two-equation model widely used in engineering. The time direction uses the second-order accuracy dual time step method and the LU-SGS implicit advancement solution. The grid uses a partitioned structured grid. In order to improve the spatial resolution to capture the flow characteristics, it is encrypted in the shock wave area.

[0072] <2> Extract shock wave surface

[0073] The principle of Lovely-Hamies identification and extraction of shock wave surface is to regard the general oblique shock wave as a normal shock wave superimposed on the uniform flow. The normal flow characteristics before and after the oblique shock wave satisfy the normal shock wave relationship. The normal direction of the shock wave is perpendicular to the local pressure gradient. Therefore, the normal Mach number can be obtained from the pressure distribution. The isosurface of the unit normal Mach number represents the detected shock wave surface. Therefore, the mathematical expression of the Lovely-Hamies algorithm for static shock wave detection based on the normal Mach number is:

[0074]

[0075] Where Ma is the Mach number vector in the direction of the local flow velocity, a is the local sound speed, and V is the local velocity. For transient shock wave detection, the movement of the shock wave must be considered, and the condition 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 direction of the pressure gradient. Due to numerical errors in interpolation, it is possible to calculate a small non-directional pressure gradient in the uniform flow region, resulting in a Mach number of n Randomization of distribution and erroneous shock wave detection. Filtering is a common strategy to avoid such pseudo shock waves. Filter factors c and η are usually introduced in the filtering method, and the local pressure gradient is made to meet the requirements.

[0080]

[0081] Where n is the unit normal vector of the measured shock wave surface.

[0082] The process of using Lovely-Hamies to generate shock waves is mainly divided into four steps:

[0083] a) Calculate the characteristic value of the pressure gradient

[0084] According to the Lovely-Haimes algorithm expression (1), the characteristic value of the pressure gradient needs 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) Equi-surface extraction based on eigenvalues

[0086] After calculating the pressure gradient, the isosurface is extracted according to formula (1). The isosurface can be extracted by contour tracking method, marching cube method and isosurface extraction algorithm based on octree.

[0087] c) Screen the isosurface to remove noise

[0088] For most of the noise, the filtering method can be used to filter out most of the noise through some restrictions. According to expression (4), η is manually specified to control the degree of noise screening; for the remaining small noise, the flooding method and DBSCAN can be used to remove it.

[0089] d) Smoothing the shock wave surface

[0090] Smoothing is beneficial to improving system performance or image quality. The Laplace algorithm can be used for smoothing the shock wave surface.

[0091] Figure 1 The shock wave surface extracted from a single swept waverider when the incoming flow Ma=6 and the attack angle α=8° is given.

[0092] <3> Count the leakage on the lower surface

[0093] Read the specified leading edge line, take the leading edge line as the starting point, and trace the shock wave surface with the normal vector of the object surface as the direction. Calculate the distance from the object surface to the shock wave surface by passing the ray with the normal vector of the object surface as the direction, and construct the grid and points by bisecting the distance and direction, interpolate each point and generate the final leading edge surface. At this time, the flux on the leading edge surface is the leakage of the lower surface of the waverider.

[0094] The flux calculation process is to multiply the normal vector of the triangle face of the leading edge by the velocity on the face, and then multiply it by the density on the face and the area of ​​the face. The specific formula is:

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

[0096] Among them, rho is the density on the surface, and area is the area of ​​the patch. The corresponding flux can be calculated by formula (5).

[0097] Figure 2 The corresponding leading edge surface extracted by single swept waverider is given.

[0098] <4> Defining the Multiplier Factor

[0099] According to the shock wave surface extracted from the flow field, the following parameters are defined:

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

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

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

[0103] The normal flow rate of the overflow surface (directionality needs to be considered, and the normal direction pointing upward is generally positive), which represents the amount of airflow from the lower surface of the aircraft to the upper surface, and the flow rate (dimensioned);

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

[0105] The projection of the lower surface of the aircraft to the far field along the flow direction is the area (dimensioned);

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

[0107] That is, the flow rate (velocity * density * area) of the projection surface, the flow rate (dimensioned);

[0108] Use piecewise function to define the multiplier factor:

[0109]

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

[0111] <5> Evaluation of waverider effect

[0112] a) Influence of flight environment on waverider effect

[0113] Investigated Figure 3 The leakage and wave-riding factor of the curved leading edge waverider with design state Ma=8 and height H=30km under different Mach numbers and height conditions are shown in Figure 4(a) and Figure 4(b). It can be seen that the wave-riding factor decreases with the increase of the angle of attack, and the corresponding lower surface overflow increases, and the wave-riding effect weakens; the incoming flow Mach number is significantly higher than the design state, and the leakage and wave-riding factor change with the angle of attack significantly weaken, and the wave-riding effect is enhanced. On the contrary, 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.

[0114] b) Effect of shape change on waverider effect

[0115] Figures 5(a) and 5(b) show single swept waveriders with different sweep angles at design state Ma=6 and altitude H=30km, keeping the volume ratios consistent between the shapes (the volume ratio calculation formula is τ=V 2 / 3 / S, where V is the volume of the waverider body and S is the projection area of ​​the top view). The results are shown in Figures 6(a) and 6(b). It can be seen that the sweep angle has a significant effect on the leading edge shock wave attachment strength. The larger the sweep angle, the lower the shock wave attachment of the leading edge, the larger the leakage, and the smaller the corresponding waverider factor.

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

[0117] This embodiment identifies and extracts the shock wave shape, counts the gas leakage from the lower surface to the upper surface, defines the waverider factor, and then establishes a mathematical model to judge the "waverider" effect, and judges the influence of the flight environment change and the shape change on the waverider effect of the waverider. The results show that the overflow of the lower surface increases with the increase of the angle of attack, the overall change range of the waverider factor is small, and the waverider effect is obvious at different angles of attack in the hypersonic state; below the design Mach number, the overflow of the lower surface of the waverider increases, the waverider factor decreases, and the waverider effect weakens; the larger the sweep angle, the greater the leakage, the smaller the corresponding waverider factor, and the weakened waverider effect.

[0118] This embodiment can exclude the influence of subjective factors by defining the waverider factor, and quantitatively evaluate the waverider effect of a waverider or a conventional layout aircraft during supersonic flight; the quantitative evaluation of the waverider effect in this embodiment can guide the layout design of a hypersonic aircraft, and avoid the damage of the waverider effect by engineering processing as much as possible; 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 as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A wave-riding effect evaluation method based on wave-riding factor, characterized in that include: Obtaining the hypersonic shock wave flow field of the waverider; The waverider hypersonic shock wave flow field is voxelized to obtain the pressure gradient of each voxel; Substitute the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, which is the shock wave surface in the flow field; De-noising the shock wave surface in the flow field to obtain a de-noised shock wave surface; The de-noised shock wave surface is smoothed using the Laplace algorithm to obtain the final flow field shock wave surface; The preset waverider leading edge line is projected onto the final flow field shock wave surface to obtain the leading edge surface, and the leakage amount of the leading edge surface is obtained; The wave multiplier factor is obtained according to the leakage of the leading edge surface.

2. The method for evaluating the waverider effect based on the waverider factor according to claim 1, characterized in that: The computational fluid dynamics method is used to obtain the hypersonic shock wave flow field of the waverider; wherein the hypersonic shock wave flow field of the waverider includes pressure p and Mach number Ma.

3. The method for evaluating the wave-riding effect based on the wave-riding factor according to claim 1, characterized in that: The Lovely-Haimes algorithm formula is: Among them, Ma n is 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 sound speed.

4. The method for evaluating the waverider effect based on the waverider factor according to claim 1, characterized in that: The isosurface is extracted by using contour tracing method, marching cube method or octree-based isosurface extraction algorithm.

5. The method for evaluating the wave-riding effect based on the wave-riding factor according to claim 1, characterized in that: The formula for removing noise is: Where ▽p is the pressure gradient of each voxel, n is the unit normal vector of the measured shock wave surface, c is the first filter factor, η is the second filter factor, |▽p max is the maximum value of the pressure gradient for each voxel.

6. The method for evaluating the waverider effect based on the waverider factor according to claim 1, characterized in that: The leakage of the leading edge surface includes: The flux of each triangle is obtained by multiplying the normal vector of the triangle on the leading edge surface by the velocity on the triangle; The leakage of the leading edge surface is obtained by integrating the flux of all triangular patches.

7. The method for evaluating the waverider effect based on the waverider factor according to claim 6, characterized in that: The flux of each triangle is obtained by the following formula: flux=dot(v,n)*rho*area; Among them, flux is the flux of each triangle, v is the velocity on the triangle, n is the normal vector of the triangle, dot() is the dot product, rho is the density of the triangle, and area is the area of ​​the triangle.

8. The method for evaluating the wave-riding effect based on the wave-riding factor according to claim 1, characterized in that: The multiplier factor is obtained by the following formula: Among them, K w is the multiplication factor, q l is the leakage of the leading edge, q p is the reference flow rate, S p is the flow projection area.

9. The method for evaluating the waverider effect based on the waverider factor according to claim 8, characterized in that: Multiplier factor K w The closer it is to 1, the stronger the vehicle's ability to "capture" shock waves and the better its waveriding performance.

10. A wave-riding effect evaluation system based on wave-riding factors, characterized in that include: The first module is used to obtain the hypersonic shock wave flow field of the waverider; The second module is used to voxelize the waverider hypersonic shock wave flow field to obtain the pressure gradient of each voxel; The third module is used to bring the pressure gradient of each voxel into the Lovely-Haimes algorithm formula to extract the isosurface in the flow field, that is, the shock wave surface in the flow field; The fourth module is used to remove noise from the shock wave surface in the flow field to obtain a denoised shock wave surface; The fifth module is used to smooth the de-noised shock wave surface using the Laplace algorithm to obtain the final flow field shock wave surface; The sixth module is used to project the preset waverider leading edge line onto the final flow field shock wave surface to obtain the leading edge surface, and obtain the leakage amount of the leading edge surface; The seventh module is used to obtain the wave multiplier factor according to the leakage amount of the leading edge surface.

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