Wide-range waverider wing body fusion configuration design method

Abstract

The invention discloses a wide-range waverider wing body fusion configuration design method. The method comprises the following steps: determining plane geometric parameters of a wide-range waverider wing body fusion configuration; generating a waverider precursor lower surface according to waverider precursor front edge line design parameters kw, phi, eta and lambda and a waverider precursor length LF; generating the upper surface of the waverider precursor; passivating the front edge of the waverider precursor; determining an upper surface and a lower surface of a fuselage: determining the upper surface and the lower surface of the fuselage through a CST curved surface parameterization method based on known data points; a front edge curved surface of the wing body fusion section is generated; the front edge of the waverider front body and the front edge of the wing are connected through a plurality of smooth curves, and the front edge curved surface of the wing body fusion section is generated on the basis of the fitted curves; according to the method, parameterization is carried out on the wave-rider wing-body fusion body configuration by adopting a CST parameterization curve and curved surface method, and an effective design method is provided for engineering application of wide-area wave-rider aircrafts.

Description

Technical Field

[0001] The present invention belongs to the technical field of wide-range aircraft, and in particular relates to a design method for a wide-range waverider wing-body fusion configuration. Background Art

[0002] The aerodynamic layout of wide-range aircraft needs to be designed to match the entire flight speed range of subsonic, trans-supersonic and hypersonic speeds. However, the optimal layout characteristics of aircraft under different speed ranges are often contradictory: in order to meet the requirements of high lift-to-drag ratio and low-speed landing at subsonic speeds, traditional aircraft often present characteristics such as small sweep angle and large wing area, which will lead to excessive drag under hypersonic conditions, rapid energy loss, and inability to cruise for a long time; for example, fighters often use components such as canards and leading and trailing edge flaps to improve low-speed lift, but too many aerodynamic components in the hypersonic stage will lead to complex wave systems of the entire aircraft, mutual interference, and unfavorable thermal protection. In addition, during wide-range flight, the aircraft's control and stability characteristics such as pressure center, focus and rudder effect will change dramatically, resulting in problems such as trim loss, reduced available lift-to-drag ratio, and even difficulty in control, which has an important impact on the overall performance. Therefore, how to obtain the optimal shape that meets the aerodynamic performance in different speed ranges under the condition of meeting complex engineering constraints is a key issue that needs to be solved in aerodynamic layout design.

[0003] The optimal layout characteristics of aircraft in different speed ranges are often contradictory. The high lift-to-drag ratio advantage of waveriders is of great application value in hypersonic conditions. However, it is difficult for traditional waveriders to meet the aerodynamic characteristics requirements at low speeds. The full-ballistic aerodynamic characteristics of the waverider layout show that its lift is seriously insufficient during the landing phase, and due to the drastic changes in the pressure center and focus in a wide speed range, the control surfaces designed based on the hypersonic state are difficult to meet the trim requirements of the subsonic state.

[0004] The wing is the core component for generating aerodynamic force in traditional low-speed aircraft. Through the reasonable design of the airfoil and wing plane, efficient annular lift and vortex lift can be generated.

[0005] However, existing technical research is all about designing and evaluating the performance of waveriders or other layouts, which cannot simultaneously meet the requirements of high lift-to-drag ratio and subsonic aerodynamic characteristics in supersonic-hypersonic conditions. In addition, existing research is all about performance evaluation of a single scheme, and the scheme design process mainly relies on empirical design. There is no clear and mature design method for reference, and it is even more difficult to directly carry out aerodynamic layout optimization. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a design method for a wide-range waverider wing-body fusion configuration, aiming to solve the problem that the existing aircraft design method cannot meet the aerodynamic performance requirements within a wide speed range. In order to realize the optimization design research of the wide-range waverider wing-body fusion configuration, this patent proposes a parameterization method for the waverider wing-body fusion configuration, realizing the full parameterization description of the benchmark layout.

[0007] The present invention proposes the following technical solutions to solve the problems existing in the prior art:

[0008] A method for designing a wide-range waverider wing-body fusion configuration, characterized in that it comprises the following steps:

[0009] Step 1: Determine the plane geometric parameters of the wide-band waverider wing-body fusion configuration: LT represents the total length of the configuration; LF represents the length of the waverider forebody; b F represents the width of the waverider forebody; b / 2 represents the half span of the configuration; L1 represents the longitudinal distance between the front end of the wing and the bottom of the waverider forebody; L2 represents the length of the fusion section along the span direction; Λ represents the sweep angle of the leading edge of the wing; Ltip represents the chord length of the wing tip; D is the blunt diameter of the waverider forebody; θ is the angle between the symmetry surface line of the upper surface of the waverider forebody at the head and the x-axis; H1 is the height of the bottom section of the waverider forebody; H2 is the maximum height constraint of the fuselage; H3 is the height constraint of the tail of the configuration; after the lower surface of the waverider forebody is given, the width of the forebody is a known quantity, and the wing span and the sweep angle of the trailing edge can be determined according to b / 2 and L2;

[0010] Step 2: Design parameters kw according to the leading edge line of the waverider front body. η and λ, as well as the waverider front length LF, generate the lower surface of the waverider front;

[0011] Step 3, generating the upper surface of the waverider precursor: determining the upper surface symmetry surface line l1 according to the upper surface design parameter θ of the waverider precursor and the height constraint H1, and representing the upper surface spanwise cross-sectional line l2 by the CST curve, thereby generating the upper surface of the waverider precursor;

[0012] Step 4, passivating the leading edge of the waverider precursor;

[0013] Step 5: Generate wing surface: Determine the wing shape according to the plane geometric parameters of the wide-band waverider wing-body fusion configuration, and use the airfoil design parameters bw i The airfoil of each longitudinal section is obtained, and then the wing surface is generated; the plane geometric parameters include the layout half width b / 2, the waverider front width b F , the wing-body fusion section width L2; the wing shape includes the wing root length, wing tip length and wing sweep angle;

[0014] Step 6: Determine the upper and lower surfaces of the fuselage: Based on the known data points of the waverider front body, as shown by the dotted line in 8 and the defined fuselage cross-section line data points, as shown in Figure 8 As shown by the double-dotted dashed line in the middle, the upper and lower surfaces of the fuselage are determined by the CST surface parameterization method;

[0015] Step 7: Obtain a wing-body blending section surface with a smooth transition between the fuselage and the wing: According to the generated fuselage and wing, determine a number of (usually 10 to 15) smooth transition curves between the fuselage and the wing, and then use the fuselage, wing and smooth curves as constraints to obtain a wing-body blending section surface with a smooth transition between the fuselage and the wing through CST surface fitting;

[0016] Step 8, generating the leading edge surface of the wing-body fusion section: describing the blunt leading edge curve of the fusion section by a cubic polynomial, and generating the leading edge surface of the wing-body fusion section by a mesh surface method;

[0017] Step 9. Parameterization results: A wide-area waverider wing-body fusion configuration with smooth surface transition is obtained.

[0018] Furthermore, the step 2 of generating the lower surface of the waverider precursor comprises the following specific steps:

[0019] ① Generate the leading edge line based on the cone-guided waverider

[0020] The generation process is as follows Figure 1 As shown: Given the incoming flow Mach number Ma and the shock wave angle β of the conical shock wave s A three-dimensional shock wave surface is obtained, and an arbitrary reference curve is defined on the YZ plane at the bottom of the shock wave surface. Here, the following cubic polynomial is used to define the reference curve on the bottom surface:

[0021]

[0022] In order to describe the curve more clearly and intuitively, let the radius of the shock wave circle be R s , the Z intercept of the reference curve is R0, and the azimuth is Let the angle between the tangent line at the intersection of the curve and the shock circle and the Y axis be η, the angle between the tangent line at the intersection of the curve and the Z axis and the Y axis be λ, and let the parameter kw = R0 / R s , after simplification, we can get:

[0023]

[0024] Thus, given the design parameters kw, η and λ, the reference curve form of equation (1) can be completely determined; then the curve is projected along the X-axis direction toward the shock wave surface to obtain an intersection line, which is the leading edge line of the waverider.

[0025] ② Solving the benchmark flow field

[0026] Due to the axisymmetric characteristics of the reference flow field, the flow characteristics on each streamline starting from the vertex are constant. Its governing equation in the axisymmetric coordinate system is the Taylor-Maccoll equation, as shown in equation (3). This governing equation is derived from the continuity equation of conical flow, the Euler equation, and the irrotational condition.

[0027]

[0028] Where r and θ represent the independent variables in radial and normal directions respectively, V max Indicates the maximum theoretical speed when the temperature is zero, V r represents the radial velocity component, and γ represents the specific heat ratio. Assuming that the incoming flow is a calorimetrically perfect gas, γ = 1.4. The normal velocity component in the axisymmetric conical flow field can be calculated using formula (4):

[0029]

[0030] By numerically solving the Taylor-Maccoll equation, the benchmark flow field can be obtained.

[0031] ③ Generate the lower surface of the waverider

[0032] Select a number of points (usually 20 to 30 points) on the leading edge of the waverider, and trace the streamlines of each point along the downstream in the reference flow field to generate the lower surface as shown in Figure 2 As shown; the streamlines are determined by the following equations:

[0033]

[0034] Where u, v and w represent the velocity components along the corresponding coordinate axes;

[0035] ④ Scale the lower surface of the waverider proportionally to the required length L F .

[0036] Furthermore, the step 3 of generating the upper surface of the waverider precursor comprises the following specific steps:

[0037] ①Use cubic polynomial to define the symmetry surface line l1

[0038] The upper surface symmetry line is determined according to the upper surface design parameter θ and the height constraint H1 of the waverider precursor, and the symmetry line l1 is defined by a cubic polynomial of the following form: Figure 5 As shown:

[0039] y=ax+bx 2 +cx 3 (6)

[0040] The polynomial coefficients a, b, c can be determined based on the geometric constraint θ and the height constraint H1. Based on the geometric constraints, the upper surface profile of the waverider precursor needs to satisfy the following constraints:

[0041]

[0042] Substituting the above constraints into equation (6), we can obtain:

[0043]

[0044] ② The CST curve is used to represent the cross-sectional profile line l2 on the upper surface

[0045] The details are as follows:

[0046] The z-direction cross-sectional profile l2 at any x position is represented by CST, as Figure 5 In l2, the expression is:

[0047]

[0048] The class function in formula (8) is defined as:

[0049]

[0050] Where N1 and N2 are the exponents of the class function, ψ is the independent variable, representing the dimensionless z coordinate,

[0051] The shape function in formula (8) is defined as:

[0052]

[0053] In formula (10), b i ,i=0,1,2,…,n is the weight factor of the polynomial; is the term of the nth-order Bernstein polynomial, ψ is the independent variable, and represents the dimensionless z-coordinate.

[0054] The values ​​of A and B in formula (8) are:

[0055]

[0056] Where y1 is the y coordinate of the leading edge point 1, and y2 is the y coordinate of the point 2 on the symmetry surface line.

[0057] ③ Generate the upper surface of the waverider precursor considering volume constraints

[0058] Select several points on the leading edge line of the waverider forebody and determine several spanwise cross-sectional lines by the above method to generate the upper surface of the waverider forebody considering the volume constraint, such as Figure 6 shown.

[0059] Furthermore, the steps of generating the wing surface in step 5 are as follows:

[0060] A. Obtain the plane geometric parameters of the wing

[0061] ① Calculate the wing root length: According to the total length L of the waverider wing-body fusion configuration T , waverider front length L F The wing root length can be calculated by the fusion section length L1;

[0062] ② Calculate the span of the wing: Based on the half-width b / 2 of the configuration, the length of the fusion section L2, and the width of the waverider front body b F , the span of the wing can be calculated;

[0063] ③ Calculate the wing tip length and the wing leading edge sweep angle;

[0064] B. The airfoil parameterization equation is shown in formula (12):

[0065]

[0066] In the formula where bw i , i=0,1,…,n are airfoil design parameters, ζ T is the trailing edge thickness.

[0067] By determining the design parameter bw i , the airfoil curve can be determined; for simplicity, all sections of the wing adopt the same airfoil, but in the actual design process, different airfoils can be used for each section;

[0068] C. Generate the upper and lower surfaces of the wing: After the airfoil is determined, scale the airfoil according to the chord length of each section to obtain the following Figure 7 The airfoil sections of the wing are shown, and then the upper and lower surfaces of the wing are generated.

[0069] Furthermore, the specific steps of determining the upper and lower surfaces of the fuselage in step 6 are as follows:

[0070] A. Select some points from the waverider front surface as known data points, such as Figure 8 As shown by the dashed line, the fuselage cross-section is defined according to the fuselage geometric constraints, as shown in Figure 8 As shown by the double-dotted line in the figure, it is taken as a known data point;

[0071] B. In order to achieve a smooth transition between the waverider forebody and the fuselage, the CST reverse fitting technology is used here to achieve the integrated characterization of the waverider forebody and the fuselage, as follows:

[0072] For CST parametric modeling of surfaces of arbitrary plane shapes, the surface can be normalized in two directions of the zx plane by changing the coordinates, and the surface can be described by Bernstein polynomials. At the same time, class functions are added in the characteristic directions of the surface, and the CST method representation of the surface is obtained as follows:

[0073]

[0074] Where ψ is the dimensionless z-coordinate, η is the dimensionless x-coordinate, and ζ is the dimensionless y-coordinate of the surface. is a class function, Sx j (η) and Sz i (ψ) is the Bernstein polynomial function in two directions, B i,j is the surface control parameter. The coordinate transformation expression is:

[0075]

[0076] where x U ,x D is the boundary of the surface in the x direction on the zx plane, z U ,z D is the boundary of the surface in the z direction on the zx plane; the relationship between ζ in formula (13) and the y coordinate of the surface is:

[0077] ζ=y / b (15)

[0078] C. Use the above CST method to fit the known points of the waverider forebody and fuselage. During the fitting process, the CST surface coefficient B i,j The solution can be obtained by Newton's method or by solving an overdetermined system of equations;

[0079] D. After getting coefficient B i,j After that, the fuselage surface is generated. Fig. 9 shown.

[0080] Furthermore, the step 7 of obtaining a wing-body fusion section curved surface with a smooth transition between the fuselage and the wing comprises the following specific steps:

[0081] ① According to the generated fuselage and wing, determine the spanwise profile of the wing-body fusion section, such as Fig.10 As shown by the double-dotted line in the figure, a cubic polynomial as shown in formula (16) is used here to define the spanwise cross-sectional profile. The coordinates and slope of the curve endpoints are substituted into formula (16) to obtain the coefficients a, b, c and d, and then the points on the curve are obtained.

[0082] y=a+bx+cx 2 +dx 3 (16)

[0083] Similarly, a cubic polynomial is used to define the leading edge of the fusion segment, such as Fig.10 As shown in , the coefficients a, b, c and d can be determined from the coordinates of the curve endpoints and the slope of the tangent at the endpoints, and then the curve can be solved.

[0084] ② Select some known points on the fuselage surface and wing surface, such as Fig.10 As shown by the dashed line in the middle, and the span-wise cross-sectional profile of the fusion section, the wing-body fusion section surface with a smooth transition between the fuselage and the wing is obtained by the above-mentioned CST surface fitting method;

[0085] Furthermore, the step eight of generating the leading edge curved surface of the wing-body fusion section comprises the following specific steps:

[0086] Select several points on the leading edge line of the fusion segment, and define the blunt leading edge curve of the fusion segment through the cubic polynomial curve of formula (16), as follows: Fig.11 As shown in . Since the coordinates of the endpoints of the curve are known, the slope at this point can be obtained from the upper and lower surface profiles of the fusion segment, as shown in Fig.11 The slope at the end point of the dotted line can be used to calculate the coefficients a, b, c and d in the formula, and the blunt leading edge curve can be calculated; according to the leading edge line of the fusion section and the arcs of each section, the blunt leading edge surface of the fusion section is generated by the mesh surface method.

[0087] Advantages and effects of the present invention

[0088] The present invention parameterizes the waverider wing-body fusion body configuration by using CST parameterized curve and surface method, and realizes smooth transition between the waverider forebody and fuselage, fuselage and wing, etc. This not only solves the problem of difficult smooth transition between surfaces, but also takes into account the requirements of the waverider forebody leading edge passivation and fuselage volume constraint, thus providing an effective design method for the engineering application of wide-range waverider aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 Schematic diagram for cone-guided waverider generation;

[0090] Figure 2 Generate a schematic diagram for the lower surface of the waverider;

[0091] Figure 3 Schematic diagram of the leading edge passivation process;

[0092] Figure 4 It is a schematic diagram of the plane geometric constraints of the wide-band waverider wing-body fusion configuration;

[0093] Figure 5 One of the schematic diagrams for generating the upper surface of the waverider precursor;

[0094] Figure 6 The second schematic diagram of the upper surface generation of the waverider precursor;

[0095] Figure 7 It is a schematic diagram of the upper surface of the rear wing;

[0096] Figure 8 It is a schematic diagram of known data points of the waverider forebody and data points of the fuselage cross-section profile;

[0097] Fig. 9 Generate schematic diagrams for fuselage surfaces;

[0098] Fig.10 This is a schematic diagram of fitting data for the wing-body fusion section;

[0099] Fig.11 This is a schematic diagram of the leading edge line of the wing-body fusion section;

[0100] Fig.12 This is a rendering of the waverider wing-body fusion configuration;

[0101] Fig.13 This is a flow chart for the design of a wide-range waverider wing-body fusion configuration.

[0102] Fig.14 Lift-to-drag ratio of waverider wing-body fusion configuration. DETAILED DESCRIPTION

[0103] Design principle of the present invention

[0104] One of the innovations: Combining the traditional waverider configuration with the wing provides a feasible idea for the design of wide-speed range aircraft. The wide-range flight includes subsonic, supersonic and hypersonic flight. The waverider has the advantage of high lift-to-drag ratio at hypersonic speeds, but its subsonic performance is poor and it is difficult to meet the aerodynamic characteristics requirements at low speeds. In the design of traditional low-speed aircraft, the wing is the core component for generating aerodynamic force. Through the reasonable design of the airfoil and the wing plane, efficient annular lift and vortex lift can be generated, thereby providing the required lift for subsonic flight. Therefore, in order to improve the performance of the waverider at subsonic speeds, combining the traditional waverider configuration with the wing is a feasible idea to achieve an efficient fusion of different design principles at high and low speeds.

[0105] Innovation point 2: A parameterization method for wide-band waverider wing-body fusion layout is proposed. This method can realize the smooth fusion of the waverider forebody and the wing and fuselage, and at the same time realize the parameterization description of the waverider wing-body fusion layout. The method is as follows: the lower surface of the forebody adopts a cone-guided waverider body configuration, the two sides of the rear body adopt a wing design, and the middle fuselage is fused with the wing and body through the CST surface to obtain a fully parameterized benchmark layout, in which the upper surface is not limited to the free stream surface to consider the volume requirements. Based on this, local engineering modification is performed on the tail to provide a certain space for the power system, RCS nozzle layout and vertical tail assembly, and an engineering layout is obtained.

[0106] Based on the above design principles, the present invention designs a wide-range waverider wing-body fusion configuration design method, such as Fig.13 As shown, the following steps are included:

[0107] Step 1: Determine the plane geometric parameters of the wide-band waverider wing-body fusion configuration: LT represents the total length of the configuration; LF represents the length of the waverider forebody; b F represents the width of the waverider forebody; b / 2 represents the half span of the configuration; L1 represents the longitudinal distance between the front end of the wing and the bottom of the waverider forebody; L2 represents the length of the fusion section along the span direction; Λ represents the sweep angle of the leading edge of the wing; Ltip represents the chord length of the wing tip; D is the blunt diameter of the waverider forebody; θ is the angle between the symmetry surface line of the upper surface of the waverider forebody at the head and the x-axis; H1 is the height of the bottom section of the waverider forebody; H2 is the maximum height constraint of the fuselage; H3 is the height constraint of the tail of the configuration; after the lower surface of the waverider forebody is given, the width of the forebody is a known quantity, and the wing span and the sweep angle of the trailing edge can be determined according to b / 2 and L2;

[0108] Step 2: Design parameters kw according to the leading edge line of the waverider front body. η and λ, as well as the waverider front length LF, generate the lower surface of the waverider front;

[0109] Step 3, generating the upper surface of the waverider precursor: determining the upper surface symmetry surface line l1 according to the upper surface design parameter θ of the waverider precursor and the height constraint H1, and representing the upper surface spanwise cross-sectional line l2 by the CST curve, thereby generating the upper surface of the waverider precursor;

[0110] Step 4, passivating the leading edge of the waverider precursor;

[0111] Additional Notes

[0112] The leading edge of the waverider is passivated as Figure 3 As shown in Figure 1, the leading edge passivation is performed by the "adding material" method. The process includes the following 5 steps:

[0113] ① For any given original sharp leading edge waverider precursor, assume that the leading edge blunting radius is R;

[0114] ② Move the upper surface of the waverider up by a distance of D = 2*R;

[0115] ③ Select a certain number of sections along the flow direction, and find the intersection of each section and the leading edge line of the upper and lower surfaces. The two intersection points form a semicircular arc with a radius of R on the current section;

[0116] ④ Generate a blunt leading edge using the mesh surface method based on the leading edge lines of the upper and lower surfaces and the arcs of each section;

[0117] ⑤ Regenerate the bottom surface, that is, generate the passivated waverider body according to the upper surface, lower surface, blunt front edge and bottom surface. body.

[0118] Step 5: Generate wing surface: Determine the wing shape according to the plane geometric parameters of the wide-band waverider wing-body fusion configuration, and use the airfoil design parameters bw iThe airfoil of each longitudinal section is obtained, and then the wing surface is generated; the plane geometric parameters include the layout half width b / 2, the waverider front width b F , the wing-body fusion section width L2; the wing shape includes the wing root length, wing tip length and wing sweep angle;

[0119] Step 6: Determine the upper and lower surfaces of the fuselage: Based on the known data points of the waverider front body, as shown by the dotted line in 8 and the defined fuselage cross-section line data points, as shown in Figure 8 As shown by the double-dotted dashed line in the middle, the upper and lower surfaces of the fuselage are determined by the CST surface parameterization method;

[0120] Step 7: Obtain a wing-body blending section surface with a smooth transition between the fuselage and the wing: According to the generated fuselage and wing, determine a number of (usually 10 to 15) smooth transition curves between the fuselage and the wing, and then use the fuselage, wing and smooth curves as constraints to obtain a wing-body blending section surface with a smooth transition between the fuselage and the wing through CST surface fitting;

[0121] Step 8, generating the leading edge surface of the wing-body fusion section: describing the blunt leading edge curve of the fusion section by a cubic polynomial, and generating the leading edge surface of the wing-body fusion section by a mesh surface method;

[0122] Step 9. Parameterization results: A wide-area waverider wing-body fusion configuration with smooth surface transition is obtained.

[0123] Furthermore, the step 2 of generating the lower surface of the waverider precursor comprises the following specific steps:

[0124] ① Generate the leading edge line based on the cone-guided waverider

[0125] The generation process is as follows Figure 1 As shown: Given the incoming flow Mach number Ma and the shock wave angle β of the conical shock wave s A three-dimensional shock wave surface is obtained, and an arbitrary reference curve is defined on the YZ plane at the bottom of the shock wave surface. Here, the following cubic polynomial is used to define the reference curve on the bottom surface:

[0126]

[0127] In order to describe the curve more clearly and intuitively, let the radius of the shock wave circle be R s , the Z intercept of the reference curve is R0, and the azimuth is Let the angle between the tangent line at the intersection of the curve and the shock circle and the Y axis be η, the angle between the tangent line at the intersection of the curve and the Z axis and the Y axis be λ, and let the parameter kw = R0 / R s , after simplification, we can get:

[0128]

[0129] Thus, given the design parameters kw, η and λ, the reference curve form of equation (1) can be completely determined; then the curve is projected along the X-axis direction toward the shock wave surface to obtain an intersection line, which is the leading edge line of the waverider.

[0130] ② Solving the benchmark flow field

[0131] Due to the axisymmetric characteristics of the reference flow field, the flow characteristics on each streamline starting from the vertex are constant. Its governing equation in the axisymmetric coordinate system is the Taylor-Maccoll equation, as shown in equation (3). This governing equation is derived from the continuity equation of conical flow, the Euler equation, and the irrotational condition.

[0132]

[0133] Where r and θ represent the independent variables in radial and normal directions respectively, V max Indicates the maximum theoretical speed when the temperature is zero, V r represents the radial velocity component, and γ represents the specific heat ratio. Assuming that the incoming flow is a calorimetrically perfect gas, γ = 1.4. The normal velocity component in the axisymmetric conical flow field can be calculated using formula (4):

[0134]

[0135] By numerically solving the Taylor-Maccoll equation, the benchmark flow field can be obtained.

[0136] ③ Generate the lower surface of the waverider

[0137] Select a number of points (usually 20 to 30 points) on the leading edge of the waverider, and trace the streamlines of each point along the downstream in the reference flow field to generate the lower surface as shown in Figure 2 As shown; the streamlines are determined by the following equations:

[0138]

[0139] Where u, v and w represent the velocity components along the corresponding coordinate axes;

[0140] ④ Scale the lower surface of the waverider proportionally to the required length L F .

[0141] Furthermore, the step 3 of generating the upper surface of the waverider precursor comprises the following specific steps:

[0142] ①Use cubic polynomial to define the symmetry surface line l1

[0143] The upper surface symmetry line is determined according to the upper surface design parameter θ and the height constraint H1 of the waverider precursor, and the symmetry line l1 is defined by a cubic polynomial of the following form: Figure 5 As shown:

[0144] y=ax+bx 2 +cx 3 (6)

[0145] The polynomial coefficients a, b, c can be determined based on the geometric constraint θ and the height constraint H1. Based on the geometric constraints, the upper surface profile of the waverider precursor needs to satisfy the following constraints:

[0146]

[0147] Substituting the above constraints into equation (6), we can obtain:

[0148]

[0149] ② The CST curve is used to represent the cross-sectional profile line l2 on the upper surface

[0150] The details are as follows:

[0151] The z-direction cross-sectional profile l2 at any x position is represented by CST, as Figure 5 In l2, the expression is:

[0152]

[0153] The class function in formula (8) is defined as:

[0154]

[0155] Where N1 and N2 are the exponents of the class function, ψ is the independent variable, representing the dimensionless z coordinate,

[0156] The shape function in formula (8) is defined as:

[0157]

[0158] In formula (10), b i ,i=0,1,2,…,n is the weight factor of the polynomial; is the term of the nth-order Bernstein polynomial, ψ is the independent variable, and represents the dimensionless z-coordinate.

[0159] The values ​​of A and B in formula (8) are:

[0160]

[0161] Where y1 is the y coordinate of the leading edge point 1, and y2 is the y coordinate of the point 2 on the symmetry surface line.

[0162] ③ Generate the upper surface of the waverider precursor considering volume constraints

[0163] Select several points on the leading edge line of the waverider forebody and determine several spanwise cross-sectional lines by the above method to generate the upper surface of the waverider forebody considering the volume constraint, such as Figure 6 shown.

[0164] Furthermore, the steps of generating the wing surface in step 5 are as follows:

[0165] A. Obtain the plane geometric parameters of the wing

[0166] ① Calculate the wing root length: According to the total length L of the waverider wing-body fusion configuration T , waverider front length L F The wing root length can be calculated by the fusion section length L1;

[0167] ② Calculate the span of the wing: Based on the half-width b / 2 of the configuration, the length of the fusion section L2, and the width of the waverider front body b F , the span of the wing can be calculated;

[0168] ③ Calculate the wing tip length and the wing leading edge sweep angle;

[0169] B. The airfoil parameterization equation is shown in formula (12):

[0170]

[0171] In the formula where bw i , i=0,1,…,n are airfoil design parameters, ζ T is the thickness of the trailing edge.

[0172] By determining the design parameter bw i , the airfoil curve can be determined; for simplicity, all sections of the wing adopt the same airfoil, but in the actual design process, different airfoils can be used for each section;

[0173] C. Generate the upper and lower surfaces of the wing: After the airfoil is determined, scale the airfoil according to the chord length of each section to obtain the following Figure 7 The airfoil sections of the wing are shown, and then the upper and lower surfaces of the wing are generated.

[0174] Furthermore, the specific steps of determining the upper and lower surfaces of the fuselage in step 6 are as follows:

[0175] A. Select some points from the waverider front surface as known data points, such as Figure 8As shown by the dashed line, the fuselage cross-section is defined according to the fuselage geometric constraints, as shown in Figure 8 As shown by the double-dotted line in the figure, it is taken as a known data point;

[0176] B. In order to achieve a smooth transition between the waverider forebody and the fuselage, the CST reverse fitting technology is used here to achieve the integrated characterization of the waverider forebody and the fuselage, as follows:

[0177] For CST parametric modeling of surfaces of arbitrary plane shapes, the surface can be normalized in two directions of the zx plane by changing the coordinates, and the surface can be described by Bernstein polynomials. At the same time, class functions are added in the characteristic directions of the surface, and the CST method representation of the surface is obtained as follows:

[0178]

[0179] Where ψ is the dimensionless z-coordinate, η is the dimensionless x-coordinate, and ζ is the dimensionless y-coordinate of the surface. is a class function, Sx j (η) and Sz i (ψ) is the Bernstein polynomial function in two directions, B i,j is the surface control parameter. The coordinate transformation expression is:

[0180]

[0181] where x U ,x D is the boundary of the surface in the x direction on the zx plane, z U ,z D is the boundary of the surface in the z direction on the zx plane; the relationship between ζ in formula (13) and the y coordinate of the surface is:

[0182] ζ=y / b (15)

[0183] C. Use the above CST method to fit the known points of the waverider forebody and fuselage. During the fitting process, the CST surface coefficient B i,j The solution can be obtained by Newton's method or by solving an overdetermined system of equations;

[0184] D. After getting coefficient B i,j After that, the fuselage surface is generated. Fig. 9 shown.

[0185] Furthermore, the step 7 of obtaining a wing-body fusion section curved surface with a smooth transition between the fuselage and the wing comprises the following specific steps:

[0186] ① According to the generated fuselage and wing, determine the spanwise profile of the wing-body fusion section, such as Fig.10As shown by the double-dotted line in the figure, a cubic polynomial as shown in formula (16) is used here to define the spanwise cross-sectional profile. The coordinates and slope of the curve endpoints are substituted into formula (16) to obtain the coefficients a, b, c and d, and then the points on the curve are obtained.

[0187] y=a+bx+cx 2 +dx 3 (16)

[0188] Similarly, a cubic polynomial is used to define the leading edge of the fusion segment, such as Fig.10 As shown in , the coefficients a, b, c and d can be determined from the coordinates of the curve endpoints and the slope of the tangent at the endpoints, and then the curve can be solved.

[0189] ② Select some known points on the fuselage surface and wing surface, such as Fig.10 As shown by the dashed line in the middle, and the span-wise cross-sectional profile of the fusion section, the wing-body fusion section surface with a smooth transition between the fuselage and the wing is obtained by the above-mentioned CST surface fitting method;

[0190] Furthermore, the step eight of generating the leading edge curved surface of the wing-body fusion section comprises the following specific steps:

[0191] Select several points on the leading edge line of the fusion segment, and define the blunt leading edge curve of the fusion segment through the cubic polynomial curve of formula (16), as follows: Fig.11 As shown in . Since the coordinates of the endpoints of the curve are known, the slope at this point can be obtained from the upper and lower surface profiles of the fusion segment, as shown in Fig.11 The slope at the end point of the dotted line can be used to calculate the coefficients a, b, c and d in the formula, and the blunt leading edge curve can be calculated; according to the leading edge line of the fusion section and the arcs of each section, the blunt leading edge surface of the fusion section is generated by the mesh surface method.

[0192] Embodiment 1

[0193] Waverider forebody design condition: Mach number 12

[0194] Shock Angle: 7.0°

[0195] Waverider precursor design parameters:

[0196] kw=0.750, φ=32.763, η=34.576, λ=11.597

[0197] <![CDATA[L T ]]> <![CDATA[L F ]]> b / 2 <![CDATA[L1]]> <![CDATA[L2]]> Λ <![CDATA[L tip ]]> D θ(deg) <![CDATA[H1]]> <![CDATA[H2]]> <![CDATA[H3]]> 37.0 18.5 11.5 3.0 1.25 60 7.882 0.1 11 3.0 3.4 2.6

[0198] Flight conditions: Mach number 12.0, flight altitude 40km

[0199] Aircraft length: 37.0 meters,

[0200] Aircraft width: 23.0 meters

[0201] Based on the above parameters, the generated waverider wing-body fusion configuration is as follows: Fig.12 As shown, Fig.14 The lift-to-drag ratio of this configuration at 12 Mach and 40km altitude is given. The lift-to-drag ratio of this configuration is the largest at an angle of attack of 6°, which is 4.54.

[0202] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A design method for a wide-range waverider wing-body fusion configuration, characterized by: The following steps are involved: Step 1: Determine the plane geometric parameters of the wide-band waverider wing-body fusion configuration: LT represents the total length of the configuration; LF represents the length of the waverider forebody; b F represents the width of the waverider forebody; b / 2 represents the half span of the configuration; L1 represents the longitudinal distance between the front end of the wing and the bottom of the waverider forebody; L2 represents the length of the fusion section along the span direction; Λ represents the sweep angle of the leading edge of the wing; Ltip represents the chord length of the wing tip; D is the blunt diameter of the waverider forebody; θ is the angle between the symmetry surface line of the upper surface of the waverider forebody at the head and the x-axis; H1 is the height of the bottom section of the waverider forebody; H2 is the maximum height constraint of the fuselage; H3 is the height constraint of the tail of the configuration; after the lower surface of the waverider forebody is given, the width of the forebody is a known quantity, and the wing span and the sweep angle of the trailing edge can be determined according to b / 2 and L2; Step 2: Design parameters kw according to the leading edge line of the waverider front body. η and λ, as well as the waverider front length LF generate the lower surface of the waverider front; kw = R0 / Rs, Rs is the shock circle radius, R0 is the Z intercept of the reference curve, is the azimuth angle, η is the angle between the tangent line at the intersection of the curve and the shock circle and the Y axis; λ is the angle between the tangent line at the intersection of the curve and the Z axis and the Y axis; Step 3, generating the upper surface of the waverider precursor: determining the upper surface symmetry surface line l1 according to the upper surface design parameter θ of the waverider precursor and the height constraint H1, and representing the upper surface spanwise cross-sectional line l2 by the CST curve, thereby generating the upper surface of the waverider precursor; Step 4, passivating the leading edge of the waverider precursor; Step 5: Generate wing surface: Determine the wing shape according to the plane geometric parameters of the wide-band waverider wing-body fusion configuration, and use the airfoil design parameters bw i The airfoil of each longitudinal section is obtained, and then the wing surface is generated; the plane geometric parameters include the layout half width b / 2, the waverider front width b F , the wing-body fusion section width L2; the wing shape includes the wing root length, wing tip length and wing sweep angle; Step 6: Determine the upper and lower surfaces of the fuselage: Based on the known data points of the waverider forebody and the defined fuselage cross-section line data points, determine the upper and lower surfaces of the fuselage by using the CST surface parameterization method; Step 7: Obtain a wing-body blending section surface with a smooth transition between the fuselage and the wing: According to the generated fuselage and wing, determine a number of (usually 10 to 15) smooth transition curves between the fuselage and the wing, and then use the fuselage, wing and smooth curves as constraints to obtain a wing-body blending section surface with a smooth transition between the fuselage and the wing through CST surface fitting; Step 8, generating the leading edge surface of the wing-body fusion section: describing the blunt leading edge curve of the fusion section by a cubic polynomial, and generating the leading edge surface of the wing-body fusion section by a mesh surface method; Step 9. Parameterization results: A wide-area waverider wing-body fusion configuration with smooth surface transition is obtained.

2. According to claim 1, a wide-range waverider wing-body fusion configuration design method is characterized by: The specific steps of generating the lower surface of the waverider precursor in step 2 are as follows: ① Generate the leading edge line based on the cone-guided waverider The generation process is as follows: given the incoming flow Mach number Ma and the shock wave angle β of the conical shock wave s A three-dimensional shock wave surface is obtained, and an arbitrary reference curve is defined on the YZ plane at the bottom of the shock wave surface. Here, the following cubic polynomial is used to define the reference curve on the bottom surface: In order to describe the curve more clearly and intuitively, let the radius of the shock wave circle be R s , the Z intercept of the reference curve is R0, and the azimuth is Let the angle between the tangent line at the intersection of the curve and the shock circle and the Y axis be η, the angle between the tangent line at the intersection of the curve and the Z axis and the Y axis be λ, and let the parameter kw = R0 / R s , after simplification, we can get: Thus, given the design parameters kw, η and λ, the reference curve form of equation (1) can be completely determined; then the curve is projected along the X-axis direction toward the shock wave surface to obtain an intersection line, which is the leading edge line of the waverider. ② Solving the benchmark flow field Due to the axisymmetric characteristics of the reference flow field, the flow characteristics on each streamline starting from the vertex are constant. Its governing equation in the axisymmetric coordinate system is the Taylor-Maccoll equation, as shown in equation (3). This governing equation is derived from the continuity equation of conical flow, the Euler equation, and the irrotational condition. Where r and θ represent the independent variables in radial and normal directions respectively, V max Indicates the maximum theoretical speed when the temperature is zero, V r represents the radial velocity component, and γ represents the specific heat ratio. Assuming that the incoming flow is a calorimetrically perfect gas, γ = 1.

4. The normal velocity component in the axisymmetric conical flow field can be calculated using formula (4): By numerically solving the Taylor-Maccoll equation, the benchmark flow field can be obtained. ③ Generate the lower surface of the waverider Select a number of points (usually 20 to 30 points) on the leading edge of the waverider, and trace the streamlines of each point downstream in the reference flow field to generate the lower surface; the streamlines are determined by the following equation: Where u, v and w represent the velocity components along the corresponding coordinate axes; ④ Scale the lower surface of the waverider proportionally to the required length L F .

3. According to claim 1, a wide-range waverider wing-body fusion configuration design method is characterized by: The specific steps of generating the upper surface of the waverider precursor in step 3 are as follows: ①Use cubic polynomial to define the symmetry surface line l1 The upper surface symmetry line is determined based on the upper surface design parameter θ and the height constraint H1 of the waverider precursor, and the symmetry line l1 is defined by a cubic polynomial of the following form: y=ax+bx 2 +cx 3 (6) The polynomial coefficients a, b, c can be determined based on the geometric constraint θ and the height constraint H1. Based on the geometric constraints, the upper surface profile of the waverider precursor needs to satisfy the following constraints: Substituting the above constraints into equation (6), we can obtain: ② The CST curve is used to represent the cross-sectional profile line l2 on the upper surface The details are as follows: The z-direction cross-sectional profile l2 at any x position is represented by CST, and the expression is: The class function in formula (8) is defined as: Where N1 and N2 are the exponents of the class function, ψ is the independent variable, representing the dimensionless z coordinate, The shape function in formula (8) is defined as: In formula (10), b i ,i=0,1,2,…,n is the weight factor of the polynomial; is the term of the nth-order Bernstein polynomial, ψ is the independent variable, and represents the dimensionless z-coordinate. The values ​​of A and B in formula (8) are: Where y1 is the y coordinate of the leading edge point 1, and y2 is the y coordinate of the point 2 on the symmetry surface line. ③ Generate the upper surface of the waverider precursor considering volume constraints By selecting several points on the leading edge line of the waverider forerunner and determining several spanwise cross-sectional profile lines using the above method, the upper surface of the waverider forerunner considering the volume constraint can be generated.

4. According to claim 1, a wide-range waverider wing-body fusion configuration design method is characterized by: The specific steps of generating the wing surface in step 5 are as follows: A. Obtain the plane geometric parameters of the wing ① Calculate the wing root length: According to the total length L of the waverider wing-body fusion configuration T , waverider front length L F The wing root length can be calculated by the fusion section length L1; ② Calculate the span of the wing: Based on the half-width b / 2 of the configuration, the length of the fusion section L2, and the width of the waverider front body b F , the span of the wing can be calculated; ③ Calculate the wing tip length and the wing leading edge sweep angle; B. The airfoil parameterization equation is shown in formula (12): In the formula where bw i , i=0,1,…,n are airfoil design parameters, ζ T is the trailing edge thickness. By determining the design parameter bw i , the airfoil curve can be determined; for simplicity, all sections of the wing adopt the same airfoil, but in the actual design process, different airfoils can be used for each section; C. Generate the upper and lower surfaces of the wing: After the airfoil is determined, scale the airfoil according to the chord length of each section to obtain the airfoil sections of the wing, and then generate the upper and lower surfaces of the wing.

5. According to claim 1, a wide-range waverider wing-body fusion configuration design method is characterized by: The specific steps of determining the upper and lower surfaces of the fuselage in step 6 are as follows: A. Select some points from the waverider front surface as known data points, define the fuselage cross-section according to the fuselage geometric constraints, and use them as known data points; B. In order to achieve a smooth transition between the waverider forebody and the fuselage, the CST reverse fitting technology is used here to achieve the integrated characterization of the waverider forebody and the fuselage, as follows: For CST parametric modeling of surfaces of arbitrary plane shapes, the surface can be normalized in two directions of the zx plane by changing the coordinates, and the surface can be described by Bernstein polynomials. At the same time, class functions are added in the characteristic directions of the surface, and the CST method representation of the surface is obtained as follows: Where ψ is the dimensionless z-coordinate, η is the dimensionless x-coordinate, and ζ is the dimensionless y-coordinate of the surface. is a class function, Sx j (η) and Sz i (ψ) is the Bernstein polynomial function in two directions, B i,j is the surface control parameter. The coordinate transformation expression is: where x U ,x D is the boundary of the surface in the x direction on the zx plane, z U ,z D is the boundary of the surface in the z direction on the zx plane; the relationship between ζ in formula (13) and the y coordinate of the surface is: ζ=y / b (15) C. Use the above CST method to fit the known points of the waverider forebody and fuselage. During the fitting process, the CST surface coefficient B i,j The solution can be obtained by Newton's method or by solving an overdetermined system of equations; D. After getting coefficient B i,j After that, the fuselage surface is generated.

6. According to claim 1, a wide-range waverider wing-body fusion configuration design method is characterized by: The specific steps of obtaining a wing-body fusion section curved surface with a smooth transition between the fuselage and the wing in step 7 are as follows: ① According to the generated fuselage and wing, the spanwise profile of the wing-body fusion section is determined. Here, the spanwise section profile is defined by a cubic polynomial such as formula (16). Substituting the coordinates and slope of the curve endpoints into formula (16), the coefficients a, b, c and d can be obtained, and then the points on the curve can be obtained. y=a+bx+cx 2 +dx 3 (16) Similarly, a cubic polynomial is used to define the leading edge of the fusion segment. The coefficients a, b, c and d can be determined by the coordinates of the curve endpoints and the slope of the tangent at the endpoints, and then the curve is solved. ② Select some known points on the fuselage surface and the wing surface, as well as the span-wise cross-sectional profile of the fusion section, and obtain the wing-body fusion section surface with a smooth transition between the fuselage and the wing through the above-mentioned CST surface fitting method; 7. The method for designing a wide-range waverider wing-body fusion configuration according to claim 1, characterized in that: The specific steps of generating the leading edge surface of the wing-body fusion section in step eight are as follows: Select several points on the leading edge line of the fusion segment, and define the blunt leading edge curve of the fusion segment through the cubic polynomial curve of formula (16). Since the coordinates of the endpoints of the curve are known, the slope at the point can be obtained from the upper and lower surface profiles of the fusion segment, and the coefficients a, b, c and d in the formula can be calculated, and the blunt leading edge curve can be calculated; according to the leading edge line of the fusion segment and the arcs of each section, the blunt leading edge surface of the fusion segment is generated by the mesh surface method.

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