Design method of gliding-cruising integrated aerodynamic shape based on minimum wave drag type line

Abstract

The application relates to a design method of a gliding-cruising integrated aerodynamic profile based on a minimum wave resistance type line, and belongs to the design field of vehicles, aircraft or ships. In view of problems such as performance mismatch in a wide speed range, complex structure and insufficient matching ability of internal and external flows of a traditional configuration, a design method of a fixed-geometry two-stage aerodynamic profile based on a wave-riding theory is constructed, a configuration of integrated fusion of a back gliding stage and an abdomen cruising stage wave-riding profile is adopted, flight state switching is realized through attitude overturning, and the aircraft has excellent aerodynamic characteristics in gliding and cruising states. In the cruising stage, based on the flow direction double wave-riding principle, the outer wave-riding wall surface and the inner wave-riding inlet are generated through streamline tracing in the integrated axial symmetric reference flow field of internal and external flows, and the forebody shock wave and the inlet entrance are effectively matched; in the gliding stage, the wave-riding profile is designed based on the minimum wave resistance theory, and a higher lift-drag ratio is obtained. The two-stage profiles share a three-dimensional leading edge, and are seamlessly fused in the unified configuration. The aircraft structure design is simplified, and the flight reliability is improved.

Description

Technical Field

[0001] This invention belongs to the field of aerodynamic layout design of near-space hypersonic vehicles, specifically relating to the design of vehicles, aircraft, or ships. Background Technology

[0002] To enhance the combat radius and penetration capability of hypersonic vehicles, air-breathing vehicles with a boost-glide-cruise combined flight mode have gradually become a research hotspot. These vehicles accelerate to a predetermined altitude via a boost phase, then enter a powerless gliding phase, relying on a high lift-to-drag ratio aerodynamic configuration to perform highly maneuverable flight in near space, exhibiting strong trajectory flexibility and unpredictability. Subsequently, upon descending to a specific altitude, the engine restarts to enter a steady-state cruise phase, improving propulsion efficiency and enhancing terminal guidance accuracy [Wei Jihua, Wang Zhaokui. Ballistic optimization of powered gliding combination for hypersonic vehicles [J]. Journal of Command and Control, 2021, 7(03):249-256.]. However, limited by the wide-range performance mismatch problem, the gliding phase requires a high lift-to-drag ratio to achieve long-distance flight, while the cruise phase requires efficient air intake and thrust matching. These two requirements are often mutually restrictive in terms of aerodynamic configuration. Traditional configurations typically struggle to achieve an ideal balance between these two phases. Therefore, how to achieve drag reduction and lift increase during unpowered gliding, while ensuring good air intake and propulsion matching during powered cruise, has become one of the key issues restricting the realization of high-efficiency flight over a wide speed range and the improvement of long-range capability for this type of aircraft.

[0003] To address this issue, applying the full waverider concept to the integrated design of gliding-cruise two-stage aircraft has become the most innovative and promising research direction. The waverider configuration, due to its ability to "ride" the shock wave and achieve an extremely high lift-to-drag ratio, provides an ideal aerodynamic platform for wide-range flight. However, the integrated design of the forebody and air intake is not a simple assembly; its core challenge lies in achieving a deep integration of the forebody compression field and engine intake requirements at both geometric and aerodynamic levels. Currently, the design of efficient waverider aircraft that can handle both gliding and cruise missions is still in the exploratory stage, with only a few publications addressing this type of multimodal configuration. Ding Feng utilized conical guide flow theory to realize the waverider characteristics of the aircraft at different Mach numbers, but due to the inherent circular shock wave exit characteristic of this method, the intake capture area and shape are significantly limited, which is detrimental to the integration of the airframe / propulsion system [Ding Feng. Research on Hypersonic Gliding-Cruise Two-Stage Waverider Design Method [D]: [Master's Thesis]. Changsha: National University of Defense Technology: 2012.]. To address this, Wang Qingwen proposed another approach based on the kissing cone theory: employing a separable fairing structure, enabling the aircraft to maintain high Mach number waveriding performance during the gliding phase by relying on its overall aerodynamic shape, and then exposing the forebody through fairing jetting after entering the cruise phase, thereby achieving waveriding at low Mach numbers. However, this approach did not consider the design of the internal flow intake [Wang Qingwen. Design of a Two-Stage Waverider Based on Kissing Theory [D]. Changsha: National University of Defense Technology, 2015.]. Leng also designed an integrated configuration of a two-stage waverider forebody / two-dimensional intake adapted to combined flight missions based on the kissing cone theory. This configuration achieves waveriding characteristics of the aircraft at high and low flight Mach numbers through fairing separation [Leng JX, Wang ZG, Huang W, “Design and investigation on the combined two-stage waverider equipped with rocket and scramjet engine” published in Energy (2024, 304: 132076). This type of method achieves multi-stage waverider performance, but it requires two approaches: one is to introduce smart variant technology into the waverider design, using smart materials to maintain waverider performance within a given Mach number as the flight mission changes; the other is to generate multiple fairings during the waverider design process, each corresponding to a different Mach number, to ensure that the multi-stage waverider can consistently maintain its waverider characteristics at different Mach numbers. Using fairings corresponding to different Mach numbers to achieve a wide speed range is currently the easiest method to implement in engineering. Optimal waverider characteristics are achieved by selectively jettisoning the fairing shell corresponding to the designed Mach number at different stages of flight.However, the compression surfaces of two- (or multi-)stage waverider aircraft are designed for several discrete design Mach numbers, making it practically impossible to fly only at a few design points. When flying at non-design Mach numbers, their "waveriding" characteristics cannot be effectively guaranteed. Furthermore, waveriders themselves have limited volume, and the multi-stage waverider surface design further divides the airframe space, placing higher demands on load distribution and structural strength. Regardless of the implementation method, both increase structural complexity and mass, hindering the achievement of efficient flight.

[0004] Therefore, there is an urgent need for an integrated aerodynamic profile design method that can achieve both gliding and cruise aerodynamic performance, has a simple and reliable structure, and good adaptability across a wide speed range. Summary of the Invention

[0005] The purpose of this invention is to address the technical problems of existing hypersonic glide-cruise combined aircraft, such as wide-range performance mismatch, complex structure, easy failure of waverider characteristics at non-design Mach numbers, poor internal and external flow matching, and insufficient volumetric efficiency. This invention provides a glide-cruise integrated aerodynamic profile design method based on a minimum wave drag profile. This method adopts a fixed geometry integrated configuration, using a shared three-dimensional leading edge of two-stage waverider profiles and a fusion design of internal and external flows in both directions. Combined with attitude switching, it achieves efficient flight over a wide speed range without the need for complex structures, balancing aerodynamic performance and volumetric efficiency, and improving aircraft reliability.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A gliding-cruise integrated aerodynamic profile design method based on minimum wave drag profiles is disclosed. The integrated gliding-cruise integrated aerodynamic profile includes two aerodynamic profiles: a dorsal gliding stage and a ventral cruise stage. The cruise stage waverider profile is further divided into an internal design area and an external design area. The internal design area includes an internal waverider forebody and an internal rotating inlet, which includes a compression profile and an isolation section. The external design area consists of an external waverider forebody and the aircraft's waverider wing. The two stages share the same three-dimensional leading edge, achieving geometric fusion within a unified configuration. A smooth transition between gliding and cruise states is achieved through attitude switching. The main purpose of attitude rotation is to allow the corresponding aerodynamic profiles to play a dominant role, meeting the different performance requirements of high lift-to-drag ratio in the gliding phase and efficient air intake and propulsion matching in the cruise phase. The entire configuration is a fixed geometry structure, without jettisonable fairings or deformable components. The design method specifically includes the following steps:

[0008] 1) Design of the integrated axisymmetric reference flow field for the cruise-stage waverider profile: Based on the requirements of hypersonic glide-cruise flight missions, the design conditions for the integrated axisymmetric reference flow field are Mach number Ma=6, altitude 30km, and angle of attack 0° at the cruise design point. According to the aircraft's requirements for forebody pre-compression capability and volume fraction, a convex curve passing through the origin is selected as the shock wave generator, and the external compression flow field is constructed based on the minimum wave drag theory. The forebody shock wave and the external compression inviscid flow field are solved inversely using the method of characteristics. Furthermore, an internal contraction flow field is constructed based on the low wave drag external compression flow field. The inlet incident shock wave curve is defined by selecting characteristic points on the generator and forebody shock wave, and then the external compression region is solved by interpolation using the method of characteristics, and the internal shock wave region and the isentropic compression region are calculated inversely. Finally, by aerodynamically fusing the internal and external flow fields along the flow direction, a continuous, smooth, and aerodynamically matched axisymmetric integrated reference flow field for internal and external flow is obtained.

[0009] 2) Design of cruise-stage external flow waverider profile: Based on the axisymmetric integrated internal and external flow reference flow field, define the flow capture tube curve (FCT) and inlet capture curve (ICC) of the cruise-stage waverider profile; according to the flow capture requirements, divide the FCT curve into an internal design zone curve and an external design zone curve, and determine the internal and external interface; perform streamline tracing on the FCT discrete points in the external compression flow field, and construct the forebody and airfoil profile that match the external compression shock wave through streamline lofting, so that the leading edge of the forebody always adheres to the shock wave and maintains the external flow waverider characteristics;

[0010] 3) Design of the internal flow wave-riding profile of the cruise-class: Based on the determined internal and external partitions and external compression flow field solution parameters, the internal inlet lip capture profile and lateral capture boundary are combined to construct the internal inlet compression section profile through streamline tracing; the inlet shroud and isolation section are generated using geometric methods, wherein the outlet cross-sectional area of ​​the isolation section is 1.2 to 1.4 times the throat cross-sectional area; so that the inlet lip is also attached to the shock wave, forming a flow-direction double wave-riding structure together with the forebody;

[0011] 4) Design of the axisymmetric reference flow field for the gliding stage: Based on the requirements of the gliding flight stage, the design conditions for the reference flow field of the gliding stage are Mach number Ma=10, altitude 37km, and angle of attack 0°. Based on the configuration volume ratio constraint, the axisymmetric shock wave generator is designed according to the minimum wave drag theory, and the external compression flow field is constructed. The inviscid reference flow field of the gliding stage is obtained by solving the characteristic line method.

[0012] 5) Design of the glider-class waverider profile: Based on the leading-edge cone (LEC) theory, the forward design method of the waverider is used, with the three-dimensional leading-edge curve of the cruise class as the geometric constraint input. Then, in the reference flow field of the glider class, the back shock streamline passing through the discrete points of the leading edge is tracked, and finally the glider-class waverider profile is formed by lofting the streamlines in each tangent plane. The glider-class and cruise-class waverider profiles are geometrically spliced ​​together to obtain the configuration of the glider-cruise integrated hypersonic vehicle.

[0013] In steps 1) and 4), the minimum wave drag theory is introduced into the two-stage aerodynamic profile design process. By designing an "outwardly convex" low wave drag shock generator, the glider stage and cruise stage achieve integrated aerodynamic profile design under the minimum wave drag design criterion, thereby reducing wave drag and improving aerodynamic efficiency throughout the entire flight envelope.

[0014] In steps 2) and 3), the design of the forebody and the intake duct in the internal design area of ​​the cruise class achieves "flow-direction double wave riding", that is, the leading edge of the forebody and the leading edge of the intake duct lip are both attached to the shock wave surface. Under the condition of integrated internal and external flow, the wave riding characteristics are not destroyed, and the shock wave detachment and intake overflow deterioration are avoided, thereby ensuring that the integrated design of the forebody and the intake duct does not destroy the wave riding characteristics.

[0015] In step 5), the glider-stage waverider profile shares the same leading edge profile as the cruise stage during the generation process, and streamline tracing is performed in the glider-stage reference flow field, so that the aircraft maintains good waverider characteristics and aerodynamic consistency in both gliding and cruise conditions.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] This invention is based on an integrated gliding-cruise design concept, designing the dorsal side of the aircraft as a gliding-stage waverider surface, which is integrated with the ventral side cruise-stage waverider surface to form an integrated configuration. This allows the aircraft to maintain waverider characteristics during both gliding and cruise phases. The rational layout of the two-stage surfaces satisfies good aerodynamic performance in each flight phase, providing a new approach to the efficient flight design of fixed-geometry two-stage aerospace vehicles. Simultaneously, through an integrated internal and external flow field design, the forebody can effectively displace the boundary layer, allowing the air intake to draw in clean airflow. The integrated gliding-cruise configuration exhibits excellent waverider performance in both gliding and cruise phases, achieving wide-speed-range, high lift-to-drag ratio flight. During the gliding phase, the gliding-stage waverider surface provides excellent lift-to-drag characteristics, increasing the aircraft's lift-to-drag ratio by approximately 0.5, while simultaneously rotating to the dorsal side... The peak heat flux at the inlet lip is reduced by 15% to 20%, significantly reducing the impact of heat flux. During cruise, the ventral flow-oriented double-wave cruise stage profile ensures good wave-riding effect. At an angle of attack of 5.5° (maximum lift-to-drag ratio condition), the lift-to-drag ratio can reach 3.21, the inlet flow coefficient is about 1.02, and the pressure ratio at the isolator outlet is about 15.93, ensuring good outflow aerodynamic characteristics while possessing excellent inflow inlet performance. The design method takes into account both volume ratio and aerodynamic performance, simplifies structural design, improves flight reliability, and provides a feasible aerodynamic profile design strategy for the development of hypersonic vehicles. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the design principle of the external compression flow field in an integrated axisymmetric reference flow field;

[0019] Figure 2 This is a schematic diagram of the design principle of the internal contraction flow field in an integrated axisymmetric reference flow field;

[0020] Figure 3 This is a two-dimensional view of the design principle of the cruise class waverider profile;

[0021] Figure 4 This is a three-dimensional view of the design principle of the cruise class waverider profile;

[0022] Figure 5 It is an isometric drawing of the gliding-cruise integrated semi-model configuration;

[0023] Figure 6 This is a front view of the gliding-cruising integrated semi-model configuration;

[0024] Figure 7 This is a graph showing the variation of the external aerodynamic characteristics of Case A at different angles of attack; the horizontal axis represents the angle of attack (AOA), and the left vertical axis represents the lift coefficient (C). L ), drag coefficient (C) D The right vertical axis represents the lift-to-drag ratio (L / D).

[0025] Figure 8These are Mach number contour plots at the plane of symmetry of Case A under different angles of attack; where (a) is AOA=0°, (b) is AOA=2°, (c) is AOA=4°, (d) is AOA=6°, and (e) is AOA=8°.

[0026] Figure 9 This is a graph showing the performance of the intake throat and outlet as a function of angle of attack; where (a) is the curve of Mach number (Ma) and flow coefficient (φ) of the throat and outlet as a function of angle of attack, with the left ordinate being Mach number (Ma), the right ordinate being flow coefficient (φ), and the abscissa being angle of attack (AOA); (b) is the curve of pressure ratio (π) and total pressure recovery coefficient (σ) of the throat and outlet as a function of angle of attack, with the left ordinate being pressure ratio (π), the right ordinate being total pressure recovery coefficient (σ), and the abscissa being angle of attack (AOA).

[0027] Figure 10 It is a comparison diagram of the theoretical shock wave profile and the simulated shock wave profile on the reference plane;

[0028] Figure 11 This is a comparison of the aerodynamic and aerothermal characteristics of Case A at a 12° angle of attack during the gliding phase at a high Mach number; where the horizontal axis represents Mach number (Ma), the left vertical axis represents heat flux density (Q), and the right vertical axis represents lift-to-drag ratio (L / D).

[0029] Figure 1-6 The markings are as follows: 1-Shock generator of the cruise-class waverider profile; 2-Forehead shock wave; 3-Inlet incident shock wave; 4-Design reference plane of the cruise-class waverider profile; 5-Internal design area; 6-External design area; 7-FCT curve of the cruise-class waverider profile; 8-ICC curve of the cruise-class waverider profile; 9-Projection curve of the inlet shock wave onto the reference plane; 10-Three-dimensional leading edge of the cruise-class waverider profile; 11-Bulge in front of the internal design area. 12 - Waverider wing in external design area; 13 - Trailing edge; 14 - Inlet side lip capture curve; 15 - Inlet lip; 16 - Inner inlet compression section profile; 17 - Streamline tracked inside the internal design area cut surface P1; 18 - Streamline tracked inside the external design area cut surface P3; 19 - Isolation section; 20 - Outer cover; 21 - Isolation section outlet; 22 - Throat profile after inlet chamfering; 23 - Glider stage waverider profile. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the following embodiments will be used in conjunction with the accompanying drawings to further illustrate the invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Rather, the invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims.

[0031] Given the high symmetry of the gliding-cruise integrated configuration, the following description uses only the half-model configuration as an example. See [link to documentation]. Figures 1 to 6 This invention provides a design method for an integrated gliding-cruising configuration, the main steps of which are as follows:

[0032] 1. Design of an axisymmetric reference flow field integrating internal and external flows for cruise-class vessels: with a cruise altitude of 30 km and an incoming Mach number of Ma... ∞ =6. With an angle of attack of 0° as the design condition, a convex low wave drag curve OA passing through the origin of the coordinate system is first selected as the shock generator 1 of the cruise stage waverider profile, where A is the endpoint of the shock generator 1 of the cruise stage waverider profile, as shown below. Figure 1 As shown, C+ and C- represent the left-moving Mach line and the right-moving Mach line in the method of characteristics, respectively. In this embodiment, all characteristic line solutions are based on the above C+ (left-moving Mach line) and C- (right-moving Mach line). The design input parameters related to the minimum wave drag profile are: L1, r(L1) / L1=0.12 and V(L1) / L1³=0.0236, where L1 is the length of the shock generator 1 of the cruise stage waverider profile, and r(L1) is the bottom radius of the shock generator 1 of the cruise stage waverider profile (i.e., Figure 1 and Figure 2In the equation (rA), V(L1) represents the volume of the shock reference flow field generator 1 of the cruise-stage waverider profile. Under the minimum wave drag constraint, the aircraft can be guaranteed to have lower wave drag and more stable waverider characteristics in a wide speed range. Under the condition of zero angle of attack free flow, the method of characteristics is used to solve the forebody shock wave 2 and the corresponding external compression flow field in reverse. Subsequently, according to the design requirements of the inlet, the starting point C of the inlet incident shock wave is selected on the forebody shock wave 2, and the ending point D of the inlet incident shock wave is selected on the shock generator 1 of the cruise-stage waverider profile. The inlet incident shock wave 3 is defined as a cubic curve, as shown in equation (1). The flow field parameters of the outer compression zone OCD are solved using the method of characteristics. This outer compression zone OCD is formed by the coordinate origin O, the inlet incident shock wave initiation point C, and the inlet incident shock wave termination point D. Then, the flow field of the inner shock wave correlation zone CDE is solved in reverse using the method of characteristics. This inner shock wave correlation zone CDE is formed by the inlet incident shock wave initiation point C, the inlet incident shock wave termination point D, and the characteristic point E of the inner contraction flow field. Finally, the inviscid flow field of the inner isentropic compression zone EFGD is solved by using the friction wall pressure on the given curves EF and DG (which is determined by the pressure at the inlet incident shock wave initiation point C and the inlet incident shock wave termination point D), combined with the flow parameters of the rightward Mach line DE, up to the throat plane GF. The internal isentropic compression region EFGD is formed by the characteristic point E of the internal contraction flow field, the streamline endpoint F traced by the inlet incident shock wave initiation point C in the internal contraction flow field, the streamline endpoint G traced by the inlet incident shock wave termination point D in the internal contraction flow field, and the inlet incident shock wave termination point D. The throat plane is perpendicular to the symmetry plane P0, and points G and F are two points located on the throat plane. The axial distance L3 from the throat plane to point C is determined by the axial distances L1 and L2 between point A and the inlet incident shock wave initiation point C. L1 is the length of the shock generator 1 of the cruise stage waverider profile (i.e., the axial distance from the origin O to the endpoint A of the shock generator 1 of the cruise stage waverider profile), and L2 is the axial distance from the origin O to the inlet incident shock wave initiation point C. The entire axisymmetric integrated internal and external flow reference flow field is formed by... Figure 1 and Figure 2 The diagram shows the common components, and the subsequent design of the cruise-stage waverider profile is all based on... Figure 3 The design of the cruise-class waverider profile is carried out on reference plane 4.

[0033] (1)

[0034] in, This represents the radial coordinate of any point on the incident shock wave curve of the air intake. This represents the axial coordinate (along the flow direction) of any point on the incident shock wave curve of the inlet. , , , These are the coefficients of the cubic polynomial equation, determined by calculation of the boundary conditions. This represents the axial distance from the origin O of the coordinate system to the starting point C of the incident shock wave in the air intake. This represents the axial coordinate of the termination point D of the incident shock wave in the air intake. This represents the radial coordinate of the inlet shock wave originating point C. This represents the radial coordinate of the termination point D of the incident shock wave in the air intake. This represents the angle between the tangent at the inlet shock wave originating at point C and the flow direction. The angle between the tangent at the termination point D of the incident shock wave in the air intake and the flow direction is represented by tan, which represents the tangent function.

[0035] 2. Design of the cruise-stage external flow waverider profile: After designing the axisymmetric integrated internal and external flow reference field, the design of the cruise-stage external flow waverider profile is completed. First, based on the flow capture requirements, the external compression flow field is divided into an internal design region 5 and an external design region 6, such as... Figure 3 As shown in the figure. Among them, P0 represents the plane of symmetry, P1 and P3 represent the tangent planes of the internal design area and the external design area, respectively, P2 represents the tangent plane at the boundary between the internal and external design areas, and P4 represents the tangent plane corresponding to the wingtip point.

[0036] The FCT curve 7 of the cruise-class waverider surface is designed using a sixth-order polynomial of equation (2), with coefficients of: a=6.7456, b=-4.5228, c=0.9091, d=-0.0500. To improve the control capability of the shape of the forebody shock wave 2, a cubic Bézier curve defined by four control points is introduced. This curve is the ICC curve 8 of the cruise-class waverider surface, and its expression is shown in equation (3). The control coefficients are: N1=(0, -0.5, 0), N2=(0, -0.365, 0.545), N3=(0, 0.365, 0.545), N4=(0, 0.5, 0); where N1, N2, N3, and N4 are the coordinates of the geometric control points of the ICC curve. Then, according to Figure 4 The geometric positions of the key design curves in each cut surface and their correspondence with the wave system structure in the reference flow field are used to scale the shock wave profile in the basic plane using equation (4) to obtain the projection curve 9 of the inlet shock wave on the reference plane. On each cut surface, the FCT curve 7 of the cruise stage waverider profile is discretized into a series of discrete points. Through these discrete points, the free streamlines intersect with the forebody shock wave 2 to obtain the geometric coordinates of the three-dimensional leading edge 10 of the cruise stage waverider profile. Subsequently, starting from each leading edge point, streamline tracing is performed in the upstream region OCD of the external compression reference flow field and the internal contraction reference flow field, such as... Figure 1 and Figure 2As shown by the streamline ab and discrete points I-II, each streamline is lofted into a flow surface, forming the bulge forebody 11 in the internal design area and the waverider wing 12 in the external design area. The aerodynamic profile of the external design area is projected onto the reference plane as the trailing edge 13. Figure 3 The trailing edge cd of the bulge precursor 11 in the internal design zone 5 of the upstream pre-compression flow of the inlet is determined, and the position of point b is adjusted to form the lower lip capture profile ab. The straight line between bd is defined as the inlet side lip capture curve 14, which is used to provide lateral compression and generate an overflow window. Finally, the inlet lip capture profile abcd is determined, where a, b, c, and d are all discrete feature points of the inlet lip capture profile.

[0037] (2)

[0038] in, The z-coordinate of the FCT curve in the reference plane. Let y be the y-coordinate of the FCT curve in the reference plane, and a, b, c, and d be the polynomial coefficients of the FCT curve.

[0039] (3)

[0040] in, The coordinates of the points on the ICC curve 8 of the cruise class waverider surface are: These are the parameter variables of the ICC curve; , , and The coordinates of the control points for defining the geometry of the ICC curve 8 of the cruise-class waverider surface.

[0041] (4)

[0042] in, The distance between the forebody shock point and the center of curvature within the kiss-shaped section is denoted as ... denoted as denoted denoted as denoted denoted as denoted denoted as denoted denoted denoted as denoted denoted denoted as denoted denoted deno The distance between the shock wave point of the air intake duct and the center of curvature within the cut surface; The radial distance of the forebody shock point B, which is the same axial distance as the endpoint A of the shock wave generator 1 wall. The radial distance is the point C at which the incident shock wave originates in the air intake.

[0043] 3. Design of the cruise-stage internal flow wave-riding profile: By discretizing the inlet lip capture profile abcd, the inlet lip 15 is determined using the intersection of the free streamline passing through the discrete point and the incident shock wave 3 in the inlet. Within each cross-section of the internal contraction flow field (CEFGD), streamline tracing is performed from the discrete inlet point towards the throat plane, such as... Figure 2As shown in Figures II-III, the throat capture profile a'b'c'd' is then determined, where a', b', c', and d' are discrete feature points of the throat capture profile. Finally, the internal inlet compression section profile 16 of the internal design area is designed. At this point, all profiles designed using the cruise-stage theoretical design method are complete. a'', b'', c'', d'' and a''', b''', c''', d''' are the four boundary points of the inlet lip and throat in three-dimensional space, respectively. Figure 4 As shown, 17 and 18 represent the streamlines traced within the internal design area's cross-section P1 and the external design area's cross-section P3, respectively. Finally, combining the design of the isolation section 19 and the outer casing 20 (the area of ​​the isolation section outlet 21 is approximately 1.2 to 1.4 times the area enclosed by the throat profile 22 after the intake duct chamfering and the symmetry plane P0, where the isolation section 19 uses a sweeping method to generate a three-dimensional profile), the aerodynamic matching of the internal flow channel and the external flow waverider surface is ensured, without disrupting the flow direction double waverider structure, thus completing the overall design of the cruise-grade internal flow profile. Here, the throat profile 22 is the throat contour line after the intake duct chamfering treatment, the isolation section outlet 21 is the downstream outlet of the isolation section 19, and the outer casing 20 is the external protective cover for the intake duct.

[0044] 4. Design of axisymmetric reference flow field for glider stage: The glider stage waverider profile is designed based on the current Mach number Ma. ∞ =10, flight altitude 37km, angle of attack 0° are the design points. Based on the configuration volume ratio constraint, the axisymmetric external flow reference field of the glider stage is designed according to the minimum wave drag theory to meet the comprehensive requirements of the glider-cruise integrated configuration for volume ratio and lift-drag performance. The design input parameters related to the minimum wave drag profile are selected as: R(x) / x=0.04, V(x) / x³=0.007, where R(x) is the radial radius of the glider stage shock wave generator at the axial coordinate x, and V(x) is the volume of the glider stage shock wave generator at the axial coordinate x. Under these parameter conditions, the three-dimensional shock wave structure corresponding to the generator and its subsequent flow field distribution are solved using the characteristic line method, thereby obtaining the reference external flow field required for the glider stage waverider profile design.

[0045] 5. Design of the glider-class waverider surface: The glider-class waverider surface 23 is constructed using a forward design method based on the leading-edge cone (LEC) theory. First, the three-dimensional leading edge 11 of the cruise-class waverider surface is used as the geometric constraint input and discretized so that each discrete point corresponds to a vertex of the leading edge cone. Under a given design Mach number, the shock surface morphology is directly determined by establishing an analytical mapping relationship between the leading edge and the shock surface. Solving this mapping relationship essentially boils down to the Apollonius geometric envelope problem between the leading edge cone and the shock circle, and its governing equation is shown in equation (5). By solving the equation and extracting the common envelope surface of all the shock surfaces corresponding to the leading edge cones, the overall shock surface morphology of the glider-class waverider surface 23 can be obtained. Based on this, the rear shock streamlines passing through the discrete points of the leading edge are traced in each tangent plane and lofted to generate the glider-class waverider surface 23. Combining the waverider profiles inside and outside the cruise stage obtained in steps 2 and 3, geometric splicing and smooth fusion are performed along the three-dimensional leading edge 11 of the common cruise stage waverider profile. The three profiles are then uniformly output to form an integrated gliding-cruising aerodynamic configuration, such as... Figure 5 and Figure 6 As shown.

[0046] (5)

[0047] in, Let these be the coordinates of the discrete points at the leading edge in the reference plane. This corresponds to the leading edge cone radius; and Let be the coordinates of the center of the shock circle to be determined and the radius of curvature, respectively.

[0048] 6. Simulation Verification and Aerodynamic Performance Analysis

[0049] To verify the feasibility and aerodynamic performance advantages of the design method of this invention, numerical simulation and aerodynamic performance analysis were conducted on the gliding-cruise integrated configuration (hereinafter referred to as "Case A") designed in this invention. The simulation was performed using ANSYS Fluent software, with a structured mesh of 6 million pixels. The boundary conditions were set as follows: the inflow was ideal gas with viscous flow; the wall was adiabatic; the inlet boundary was a pressure far-field boundary; and the outlet boundary was a pressure outlet boundary. The simulation results are as follows: Figures 7 to 11 As shown, the specific simulation conditions are consistent with the design conditions to ensure the effectiveness and relevance of the simulation results.

[0050] 6.1 Simulation Verification of External Flow Aerodynamic Characteristics during Cruise Phase

[0051] Figure 7 This demonstrates the changes in the external aerodynamic characteristics of Case A under different angles of attack. Figure 7It can be seen that as the angle of attack increases, the lift coefficient (C) of Case A increases. L The drag coefficient gradually increases with the angle of attack, while the slope of the lift line slightly decreases. Unlike the traditional integrated configuration where the drag coefficient gradually increases with the angle of attack, Case A's drag coefficient (C...) gradually increases with the angle of attack. D The lift-to-drag ratio (L / D) increases with angle of attack from 0 to 2°, decreases from 2 to 4°, and then gradually increases with further angle of attack. This is attributed to the fact that the waverider surface on the back generates greater drag than the conventional horizontally stretched upper surface in the small angle of attack range, resulting in the aforementioned trend in the drag coefficient curve. The lift-to-drag ratio (L / D) first increases and then decreases with increasing angle of attack, reaching a maximum of 3.21 at approximately 5.5° angle of attack. This indicates that this configuration can achieve optimal lift-to-drag characteristics by adjusting the angle of attack during the cruise phase, meeting the requirements for long-range cruise.

[0052] 6.2 Simulation Verification of Flow Field Characteristics During Cruise Phase

[0053] Figure 8 Mach number contour plots at the Case A symmetry plane were compared under different angles of attack (AOA), where the blue and pink dashed lines represent the preset forebody shock wave and the inlet shock wave, respectively. Figure 8 As shown in (a) to (e), at an angle of attack of 0°, due to the influence of the boundary layer, the shape and position of the shock wave between the fuselage and the air intake deviate slightly from the theoretical value, but the overall fit is good; as the angle of attack increases, the forebody shock wave moves inward, thereby enhancing the air intake flow capture capability, which is in line with the design expectations. Figure 8 The diagrams within the boxes further show magnified views of the flow field near the inlet shoulder. It can be seen that no separation bubbles are induced at the inlet shoulder under various angles of attack conditions, proving that the design method of this invention can effectively avoid flow field separation caused by shock wave / boundary layer interaction, and ensure the stability of aerodynamic performance during the cruise phase.

[0054] 6.3 Simulation Verification of Inlet Aerodynamic Performance during Cruise Phase

[0055] Figure 9 This reveals the variation of the inlet's aerodynamic performance with angle of attack. For example... Figure 9 As shown in (a), based on the theoretical capture area at zero angle of attack, the flow coefficient φ exhibits a non-linear growth pattern with a gradually slowing rate of increase. When the angle of attack (AOA) is 0°, the flow coefficient φ≈0.88, gradually increasing with the angle of attack, reaching approximately 1.02 at 5.5° (maximum lift-to-drag ratio condition) and approximately 1.09 at 8°. This trend is mainly due to the increased lateral pressure gradient on the airframe surface caused by the increased angle of attack, resulting in more airflow overflowing from the overflow window, offsetting the flow capture gain brought about by the increased angle of attack. Therefore, the rate of increase gradually slows down, consistent with the flow characteristics of hypersonic inlets. Conversely, the average Mach number of the inlet throat... th With the average Mach number at the exit of the isolation section e All decrease gradually as the angle of attack increases.

[0056] from Figure 9 As shown in (b), the intake throat pressure ratio π th Compared with the pressure ratio π at the outlet of the isolation section e The π value increases linearly with the angle of attack: at 0° angle of attack th ≈17.0, π e The coefficient of performance (σ) increases to approximately 14.0 at an angle of attack of 5.5°, reaching approximately 22.0 and 15.93 respectively, and further increases to approximately 24.5 and 17.8 at an angle of attack of 8°, indicating that the intake manifold pressurization capacity continuously increases with the angle of attack, meeting the engine's demand for incoming flow compression. Conversely, the throat total pressure recovery coefficient (σ) is approximately 14.0. th With the total pressure recovery coefficient σ at the outlet e The trend of accelerating decline is observed at an angle of attack of 0°. th ≈0.46、σ e The nonlinear characteristics are approximately 0.42, decreasing to approximately 0.43 and 0.39 at an angle of attack of 5.5°, and further decreasing to approximately 0.40 and 0.37 at an angle of attack of 8°. This nonlinear characteristic is closely related to the increased proportion of low kinetic energy flow and the enhanced shock wave / boundary layer interaction, which is consistent with the flow loss characteristics of hypersonic inlets.

[0057] comprehensive Figure 9 As shown in (a) and (b), Case A of this invention exhibits relatively superior inlet aerodynamic performance over a wide range of angles of attack. Particularly at an angle of attack of 5.5°, close to the maximum lift-to-drag ratio, the inlet flow coefficient φ is approximately 1.02, and the pressure ratio, total pressure recovery coefficient, and Mach number at the isolator outlet section are approximately 15.93, 0.43, and 2.94, respectively. These figures fully meet the engine intake requirements during cruise, verifying the rationality and effectiveness of the cruise stage internal flow wave-riding profile design of this invention.

[0058] 6.4 Simulation Verification of Wave Ride Characteristics During Gliding Phase

[0059] The gliding-cruise integrated configuration design method proposed in this invention can effectively alleviate heat accumulation on the lower surface and significantly reduce the heat flux peak of key parts such as the air intake lip through fuselage rotation. At the same time, it can switch the waverider profile according to different flight path requirements and use the back gliding stage profile to achieve waveriding flight, thereby increasing the lift-to-drag ratio of the aircraft and further improving its range.

[0060] To verify the effectiveness of the glider class waverider profile design, Figure 10 The theoretical shock wave profile and the simulated wave system on the reference plane were compared. From Figure 10 As can be seen, the theoretical shock wave profile (i.e., the black dashed line in the figure) basically matches the simulated shock wave profile without significant deviation, proving the accuracy of the gliding-stage surface wave-riding design and ensuring that the aircraft can stably "ride" on the shock wave during the gliding phase, thus obtaining excellent lift-drag characteristics.

[0061] 6.5 Simulation Verification of Aerodynamic and Aerothermal Characteristics during Gliding Phase

[0062] Figure 11 This invention, Case A, demonstrates the aerodynamic and aerothermal characteristics of normal and inverted (back-down) flight at a 12° angle of attack during the gliding phase at high Mach numbers. The blue and red lines represent the variation of heat flux density (Q) and lift-to-drag ratio (L / D) at the same point on the inlet lip with Mach number (Ma), respectively. The dashed and solid lines represent the conventional normal flight configuration and the inverted flight configuration, respectively. Flip Q represents the heat flux density at a specific point on the inlet lip of a flip-type intake configuration. Normal For the heat flux density at the same point on the inlet lip of a conventional forward-flight configuration, L / D Flip For the lift-to-drag ratio of the flip-out configuration, L / D Normal For conventional positive flight configuration, the lift-to-drag ratio is [not specified]. Figure 11 It is evident that, across the entire Mach number range, the lift-to-drag ratio of the flip configuration is significantly higher than that of the conventional forward-flying configuration, specifically by approximately 0.5. This indicates that the aerodynamic configuration can effectively utilize its dorsal glide stage profile to extend the aircraft's range, significantly enhancing its long-distance flight capability during the gliding phase. Aerodynamic-thermal numerical simulations revealed that by flipping the fuselage, the air intake can be positioned in a region with weaker shock wave intensity, effectively avoiding the direct impact of strong shock waves on the air intake lip. Compared to the non-flipped state, the peak heat flux near the air intake lip is significantly reduced after flipping, with a decrease of 15% to 20%. This demonstrates that the aerodynamic configuration of this invention can effectively utilize the fuselage flipping method to reduce heat accumulation on the lower surface, thereby reducing the overall structural temperature gradient and improving the aircraft's thermal protection performance and flight safety.

[0063] 7. Summary of Design Core and Advantage Validation

[0064] The core innovation of this invention lies in breaking through the inherent limitations of traditional gliding-cruise configurations, which rely on separate stage designs and fairing jetting or variants for operational switching. Instead, it integrates the two-stage waverider profiles (ventral and dorsal) of the aircraft under the minimum wave drag criterion, achieving geometric fusion of the two profiles through a shared three-dimensional leading edge. Simulation verification shows that the cruise-stage waverider profile consists of two design regions: an inner and an outer region. The inner region includes the waverider forebody and the compression structure of the internal inlet, while the outer region comprises the extension of the waverider forebody and the airfoil. Based on an axisymmetric reference flow field integrating internal and external flows, the cruise-stage profile's lower surface can effectively match the three-dimensional external compression shock wave, maintaining a stable waveriding state and possessing superior lift-drag performance. Simultaneously, through the sealing effect of the three-dimensional internal contraction shock wave, the internal inlet effectively captures the entire inflow of the incoming air, meeting the propulsion system's intake requirements during the cruise phase.

[0065] In the glider stage design, the three-dimensional leading edge of the cruise stage is used as a common geometric constraint. An axisymmetric external flow field is constructed based on the minimum wave drag theory as the design foundation, ensuring that the glider stage profile possesses strict wave-riding characteristics under design conditions. By arranging the glider stage profile on the back of the aircraft and maintaining geometric and aerodynamic consistency with the cruise stage profile at the three-dimensional leading edge, seamless integration of the two stage profiles is achieved. This configuration allows for a smooth switch between gliding and cruise modes simply through attitude flipping, enabling the corresponding aerodynamic profiles to play their dominant roles. This results in a high lift-to-drag ratio during the gliding phase for long-distance flight, and efficient compression of the incoming flow and good matching with the propulsion system during the cruise phase.

[0066] Compared to traditional phased independent designs, fairing-launching, or variant solutions, this invention focuses on a fixed geometry integration. Through the collaborative design of two-stage waverider surfaces and shared leading-edge constraints, it achieves simultaneous optimization of aerodynamic performance, intake performance, and thermal protection performance across a wide speed range and multiple operating conditions. This not only simplifies structural design and improves flight reliability but also effectively overcomes the technical bottleneck of the incompatibility between gliding and cruise performance. Simulation verification further confirms that the configuration of this invention possesses excellent comprehensive performance in both cruise and gliding phases. Its design concept is not a simple superposition of existing technologies but rather a novel aerodynamic design paradigm built for fixed-geometry two-stage aerospace vehicles, providing an innovative approach to the efficient design of such vehicles.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent variations and modifications made in accordance with the claims of the present invention should fall within the scope of protection of the present invention.

Claims

1. A gliding-cruise integrated aerodynamic profile design method based on minimum wave drag profile, characterized in that, The designed aerodynamic profile adopts a fixed geometry integrated configuration, including a dorsal gliding-stage waverider profile and a ventral cruise-stage waverider profile. The two profiles share the same three-dimensional leading edge, and the switching between gliding and cruise states is achieved through attitude flipping. The design method specifically includes the following steps: 1) Design of an integrated axisymmetric reference flow field for cruise-class internal and external flows: Based on the flight conditions and mission requirements during the cruise phase, a convex low wave drag curve that meets the design requirements is selected as the forebody shock wave generator based on the minimum wave drag theory; the integrated internal and external flow field is solved using the method of characteristics, and the smooth transition between the internal and external flows at the interface is achieved through streamline tracing, forming a complete integrated axisymmetric reference flow field for aerodynamic matching. 2) Design of the cruise-class external flow waverider profile: Based on the integrated axisymmetric reference flow field of internal and external flow, define the flow capture tube curve, and determine the intake capture boundary by shock wave profile scaling; divide the flow capture tube curve into internal design area curve and external design area curve, corresponding to the internal design area and external design area of ​​the cruise-class, generate the forebody and airfoil profile by streamline tracing, so that the leading edge of the forebody is attached to the shock wave surface, and complete the design of the external flow waverider profile; 3) Design of the cruise-stage internal flow wave-riding profile: Discretize the intake lip capture profile, determine the intake leading edge by the intersection of the free streamline and the incident shock wave, and trace the streamline to the throat section in the internal contraction flow field to generate the internal turning intake compression section profile; combine the geometric transition method to complete the design of the isolation section and the outer cover, so that the intake lip leading edge is also attached to the shock wave surface, forming a complete cruise-stage internal flow wave-riding profile; 4) Design the axisymmetric reference flow field of the glider stage: Based on the flight conditions during the gliding phase, the axisymmetric flow field of the glider stage is constructed according to the minimum wave drag theory; the axisymmetric reference flow field of the glider stage is obtained by solving the method of characteristics. 5) Design of the glider-class waverider profile: The waverider forward design method is adopted, with the three-dimensional leading edge of the cruise class as a common leading edge constraint. The three-dimensional leading edge is discretized into multiple points. The waverider profile of the glider class is formed by tracing the streamlines in each tangent plane in the axisymmetric reference flow field of the glider class using the kissing theory. The waverider profile of the glider class is geometrically spliced ​​and smoothly integrated with the internal flow waverider profile of the cruise class and the external flow waverider profile of the cruise class along the common three-dimensional leading edge to form a complete fixed geometry glider-cruise integrated aerodynamic profile configuration.

2. The gliding-cruise integrated aerodynamic profile design method based on minimum wave drag profile according to claim 1, characterized in that, The flow capture tube curve mentioned in step 2) is a polynomial curve. The Bezier curve is used as the shock wave profile curve to constrain the shock wave structure. The intake capture boundary and the side lip capture curve are determined by shock wave profile scaling.

3. The gliding-cruise integrated aerodynamic profile design method based on minimum wave drag profile according to claim 1, characterized in that, In step 3), the isolation section is generated into a three-dimensional surface by sweeping, and the cross-sectional area of ​​the isolation section outlet is 1.2 to 1.4 times the cross-sectional area of ​​the throat.

4. The gliding-cruise integrated aerodynamic profile design method based on minimum wave drag profile according to claim 1, characterized in that, In steps 2) and 3), the leading edge of the forebody and the leading edge of the intake lip are attached to the same forebody shock surface, forming an outer wave-riding and inner wave-riding structure arranged sequentially along the flow direction, constituting a flow direction double wave-riding layout, so that the integrated design of the forebody and the intake duct maintains complete wave-riding characteristics.

5. The gliding-cruise integrated aerodynamic profile design method based on minimum wave drag profile according to claim 1, characterized in that, The waverider forward design method described in step 5) is based on the leading edge cone theory. The overall shock surface morphology of the glider class is determined by solving the geometric envelope of the leading edge cone and the shock wave. The streamline tracing and surface lofting in each slit are completed using the kissing theory, so as to realize the geometric splicing and smooth fusion of the waverider surfaces of the glider class and the cruise class.

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