Integrated design method of three-inlet channel with double-shock wave precursor

Abstract

The three-inlet integrated design method of double-waverider forebody is considered, which is related to the integrated design of hypersonic vehicle forebody / inlet. According to the design conditions, the double-waverider forebody and one middle internal contraction inlet and two symmetrical external internal contraction inlets are given. The middle internal contraction inlet is designed by tracing the flow lines of three-dimensional internal contraction axisymmetric reference flow field, and the external internal contraction inlets are also designed by tracing the flow lines of three-dimensional internal contraction axisymmetric reference flow field. The internal contraction reference flow field of the internal waverider forebody and the external contraction flow field of the external waverider forebody are aerodynamically coupled, so that the forebody and the lower surface of the middle internal contraction inlet maintain waverider characteristics, maintain the overall aerodynamic performance, and arrange two symmetrical external internal contraction inlets to improve the captured flow rate, further compress the incoming flow, and improve the aerodynamic performance and stability of the body; both efficiency and performance requirements are considered.

Description

Technical Field

[0001] The present invention relates to a hypersonic aircraft, and in particular to a three-inlet integrated design method considering a double-rider wavefront. Background Art

[0002] Hypersonic air-breathing propulsion, as a highly promising near-space propulsion method, has attracted considerable attention in the aerospace field. Due to the complexity of hypersonic flows, the integration of the airframe and propulsion system is a key issue that needs to be addressed in hypersonic flight. The key lies in the integration of the airframe and the inlet. This integrated design requires an optimized inlet design that achieves high compression ratio, high total pressure recovery, and a large capture area while maintaining the hypersonic vehicle's lift-to-drag ratio.

[0003] Since Nonweiler first proposed the concept of "waverider" (Nonweiller TR F. Aerodynamic Problems of Manned Space Vehicle [J]. Journal of the Royal Aeronautical Society, 1959, 63(9): 521-528), waveriders with high lift-to-drag ratios have been widely used in the integrated design of air-breathing hypersonic vehicles. Currently, most inlet designs are based on uniform inlet flow, leading to the early focus of integrated design research on the vehicle forebody, that is, setting a local plane in front of the inlet entrance for flow straightening. In order to enable the waverider forebody to generate a relatively uniform incoming flow, early waverider forebody designs were based on wedge flow fields. Starkey (Starkey R, Lewis M. Aerodynamic sofabox constrained waverider missile using multiple scramjets [C]. AIAA 1999-2378, 1999) adopted a wedge-guided waverider forebody for integrated design. However, due to the limitation of the plane shock wave, this scheme had problems such as excessive dihedral angle and low volumetric efficiency. Takashima (Takashima N, Lewis M J. Waverider configurations based on non-axisymmetric flow fields for engine airframe integration [R]. AIAA-1994-0380, 1994.) proposed a waverider design method for wedge-cone flow fields. Jones (Jones KD, Sobieczy H, Seebass AR, et al. Waverider design for generalized shock geometries [J]. Journal of Spacecraft The close waverider principle proposed by

[15] (ft&Rockets, 1993, 32(6):957-963) can design the waverider forebody according to the shape of the shock wave, thereby increasing the degree of freedom in the integrated design of the waverider forebody and the hypersonic inlet. These design methods must constrain the shape of the waverider forebody in order to provide a uniform flow field for the inlet, which greatly limits the design space for the integration of the waverider forebody and the inlet. Therefore, reducing the requirements of the inlet for the incoming flow can greatly increase the diversity of the waverider design and greatly broaden the research direction of the integrated design of the aircraft.

[0004] To improve the adaptability of the inward turning inlet to non-uniform inflow, an integrated design method of the body inlet sharing the reference flow field is proposed. The method mainly includes the osculating inward turning cone waverider / inlet integrated configuration proposed by He XZ (He XZ, Le L, Zhou Z, et al. Osculating inward turning cone waverider / inlet (OICWl) design methods and experimental study R. AIAA-2012-5810, 2012.), an axisymmetric inward contraction reference flow field is designed, the guide line type of the waverider forebody is given and the waverider forebody configuration is tracked, and then the lip line type of the inlet at the axial position of the spillage is given and the inlet surface is tracked, so that the flow field at the inlet of the inlet matches the pre-compression flow field of the forebody. You YC et al. (You Y C, Zhu C X, Guo J L. Duel wave rider concept for the integration of hypersonic inward-turning inlet and airframe forebody, AIAA Paper 2009-7421, 2009.) proposed the concept of integrated design of double waverider forebody inlet, the reference flow field of the forebody of the aircraft includes the inner deflection flow field and the outer deflection flow field, the shocks of the two are smoothly connected in the spanwise direction, and the inner waverider inlet matched with the inner deflection flow field is designed downstream of the inner deflection flow field. This method flexibly connects the inner / outer deflection flow field, so that the lift is combined with the pre-compression forebody surface; Li YQ et al. (Li YQ. Integrated design method of hypersonic inward and outward flow based on double waverider theory [D]. Xiamen University, 2018.) further developed the integrated design method of double channels to improve the contraction efficiency of the inlet.

[0005] At present, the design of the hypersonic vehicle inlet basically adopts uniform inflow for simplification, which not only limits the forebody configuration of the aircraft, but also greatly affects the overall performance of the forebody and the inlet. Considering the non-uniformity of the inlet inflow caused by the double waverider forebody boundary layer and the leading edge curved shock, the design of the inlet that can actively adapt to the non-uniform inflow is more conducive to the research and development of the hypersonic forebody / inlet integration. SUMMARY

[0006] The purpose of the present application is to provide a three-inlet integrated design method considering the double waverider forebody, which aims at the above technical problems existing in the prior art.

[0007] In the three-inlet integrated design method considering the double waverider front described in the present invention, a double waverider front and a central inward-contracting air inlet and two symmetrical outward-contracting air inlets arranged along the span direction are provided; the double waverider front is composed of an inner waverider front and an outer waverider front, and the central inward-contracting air inlet and the outward-contracting air inlet are both provided with an inlet contraction profile, an inlet lip, an inlet shoulder and an inlet isolation section.

[0008] The present invention provides a three-inlet integrated design method considering a double-rider wavefront, comprising the following steps:

[0009] (1) Design of the double-rider wavefront: Design the reference flow field of the double-rider wavefront, give the bottom projection line of the leading edge line of the double-rider wavefront, and perform streamline tracing in the reference flow field to generate the lower surface of the double-rider wavefront;

[0010] (2) Design of the central inward-converging inlet: Solve the three-dimensional central inward-converging inlet reference flow field based on the shock wave surface design of the inner waverider front of the double waverider front;

[0011] (3) Designing a two-dimensional projection shape of the inlet of the three-dimensional central inward contraction air inlet according to the air intake requirements, performing streamline tracking in the three-dimensional inward contraction reference flow field in step (2), obtaining the profile of the three-dimensional central inward contraction air inlet, and inverting the air inlet after modification;

[0012] (4) Design of the outer inner contraction inlet: Based on the non-uniform incoming flow after the outer waverider front of the double waverider is pre-compressed, the three-dimensional outer inner contraction inlet reference flow field is solved;

[0013] (5) According to the air intake requirements, the two-dimensional projection shape of the three-dimensional outer inner contraction air intake duct entrance is designed. In step (4), streamlines are tracked in the three-dimensional inner contraction reference flow field to obtain the profile of the three-dimensional outer inner contraction air intake duct. After the profile is modified, the air intake duct is inverted.

[0014] In step (2), the incoming flow at the entrance of the designed three-dimensional central inward contraction air inlet is non-uniform, and is the shock wave surface of the inner wave rider front of the double wave rider front. The shock wave surface is first discretized into an incident shock wave, and the outflow parameters are solved using the curved shock wave theory to design a reference flow field, and then the profile of the air inlet is generated in the reference flow field.

[0015] In step (4), the inlet flow of the designed three-dimensional outer inner contraction air inlet is also non-uniform, which is the airflow after the outer wave rider front of the double wave rider front is pre-compressed. Similarly, the parameters of the outflow must be solved using the bending shock wave theory, and then the reference flow field of the air inlet is generated based on the solved parameters.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] This design method generates a three-inlet design for a double waverider front, taking into account both the flow and transverse dimensions. First, along the flow direction, the double waverider front's reference flow field utilizes a full waverider design with integrated internal / external flows, achieving aerodynamic coupling between the front and the central inlet, minimizing aerodynamic interference with the airframe and ensuring waveriding characteristics. Second, within the spanwise arrangement of the three inlets, the internally contracting reference flow field of the central inlet is coupled with the externally contracting reference flow field of the front, achieving an integrated internal / external flow design. The reference flow field of the outer inlet is designed based on the pre-contracted flow of the outer waverider front, ensuring full flow capture in the outer inlet, achieving the design requirements of high contraction ratio, high total pressure recovery, and large capture area for the airframe / inlet integration. This invention fully considers the complex flow field characteristics of the double waverider front and the performance requirements of the inlet. By combining streamline tracing with reference flow field solution, an inlet can be precisely designed to meet performance requirements. In addition, for the treatment of non-uniform incoming flow, methods such as bending shock wave theory are adopted to ensure the accuracy and reliability of the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a design diagram of the basic flow field of the double-rider wavefront.

[0019] Figure 2 It is a schematic diagram of the structure of the double-multiplier wavefront.

[0020] Figure 3 It is a two-dimensional projection diagram of the inlet and outlet sections of the central inward-contracted air inlet.

[0021] Figure 4 It is a schematic diagram of the half-section structure of the central inward-retracted air intake duct.

[0022] Figure 5 It is a two-dimensional projection diagram of the inlet and outlet sections of the outer inner contraction air intake duct.

[0023] Figure 6 It is a schematic diagram of the half-section structure of the outer inner contraction air intake duct.

[0024] Figure 7 It is a schematic diagram of the overall structure of the three-inlet design method considering the double-rider wavefront.

[0025] Figure 1: 1 represents the inner wave rider forerunner corresponding to the inner contraction flow field, 2 represents the outer wave rider forerunner corresponding to the outer contraction flow field, 3 represents the shock wave generated by the inner contraction flow field, 4 represents the shock wave generated by the outer contraction flow field, 5 represents the lip of the middle inner contraction air inlet, 6 represents the two-dimensional projection shape of the inlet of the middle inner contraction air inlet, 7 represents the leading edge capture line of the middle inner contraction air inlet, 8 represents the compression line obtained by tracing the streamline of the middle inner contraction air inlet, 9 represents the compression surface of the middle inner contraction air inlet, 10 represents the shoulder line of the middle inner contraction air inlet, 11 represents 12 represents the isolation section of the middle inward-contracting air inlet duct, 13 represents the lip of the outer inward-contracting air inlet duct, 14 represents the two-dimensional projection shape of the inlet of the outer inward-contracting air inlet duct, 15 represents the leading edge capture line of the outer inward-contracting air inlet duct, 16 represents the compression line obtained by tracing the streamline of the outer inward-contracting air inlet duct, 17 represents the compression surface of the outer inward-contracting air inlet duct, 18 represents the shoulder line of the outer inward-contracting air inlet duct, 19 represents the isolation section of the outer inward-contracting air inlet duct, and 20 represents the outlet of the isolation section of the outer inward-contracting air inlet duct. DETAILED DESCRIPTION

[0026] The following embodiments will further illustrate the present invention with reference to the accompanying drawings.

[0027] like Figures 1 to 7 As shown, in the three-inlet integrated design method considering the double-rider wavefront, the double-rider wavefront generated by the axisymmetric internal and external flow coupling reference flow field is composed of an inner waverider front 1 corresponding to the inner contraction flow field and an outer waverider front 2 corresponding to the outer contraction flow field; the central three-dimensional inward contraction air inlet is composed of a lip 5 of the central inward contraction air inlet, a leading edge capture profile 7 of the central inward contraction air inlet, a compression profile 9 of the central inward contraction air inlet, a shoulder profile 10 of the central inward contraction air inlet, an isolation section 11 of the central inward contraction air inlet, and an outlet 12 of the isolation section of the central inward contraction air inlet; the outer three-dimensional inward contraction air inlet is composed of a lip 13 of the outer inward contraction air inlet, a leading edge capture profile 15 of the outer inward contraction air inlet, a compression profile 17 of the outer inward contraction air inlet, a shoulder profile 18 of the outer inward contraction air inlet, an isolation section 19 of the outer inward contraction air inlet, and an outlet 20 of the isolation section of the outer inward contraction air inlet.

[0028] The main implementation steps of the three-inlet integrated design method considering the double-rider wavefront are as follows:

[0029] (1) Designing a double-rider wavefront: Based on the design requirements, the reference flow field of the internal flow / plane and external flow aerodynamic coupling is solved, and the bottom projection profile of the leading edge profile of the double-rider wavefront is given. The bottom projection profile of the discrete leading edge profile is used to obtain the leading edge line and perform streamline tracing in the reference flow field. During the streamline tracing process, the shock wave 3 generated by the inner contraction flow field defines the boundary of the inner wavefront, and the shock wave 4 generated by the outer contraction flow field defines the boundary of the outer wavefront. The inner wavefront 1 corresponding to the inner contraction flow field and the outer wavefront 2 corresponding to the outer contraction flow field of the double-rider wavefront are obtained.

[0030] Specifically, the design conditions and expected performance indicators such as total pressure recovery and flow coefficient in the inlet can be determined first. Use CFD software (such as ANSYS Fluent, CFX, or Star-CCM+) to establish an axisymmetric internal and external flow coupling model. Set boundary conditions, including free flow conditions and wall conditions, and solve to obtain a stable reference flow field. Based on the design requirements, preliminarily set the bottom projection of the leading edge profile of the double waverider front. In the reference flow field, discretize the bottom projection of the leading edge profile, and initiate streamline tracing at each discrete point. The streamline tracing direction should follow the incoming flow direction until the streamline leaves the computational domain or reaches the predetermined tracing length. Based on the streamline tracing results, generate the geometric shapes of the inner waverider front 1 corresponding to the inner contracting flow field and the outer waverider front 2 corresponding to the outer contracting flow field. The inner waverider front should closely follow the shock wave surface in the inner flow field, while the outer waverider front should be designed based on the shock wave and compression effects in the outer flow field.

[0031] (2) Designing the central inner contraction air inlet: Based on the shock wave surface of the inner waverider precursor 1 corresponding to the inner contraction flow field in step (1), the three-dimensional incident shock wave is discretized, and then the reference flow field of the central inner contraction air inlet is solved using the bending shock wave theory based on the shock wave parameters of the discrete incident shock wave to ensure that the flow field meets the design requirements of the air inlet; the bending shock wave control equation is as follows:

[0032]

[0033] Where p is pressure, δ is flow angle, μ is Mach angle, ρ is density, V is stream velocity, w is circumferential velocity, γ is specific heat ratio, j is judgment factor, s is streamline, l is characteristic line, φ is circumferential angle, P is the derivative of pressure along streamline, and D is the derivative of flow angle along streamline.

[0034] (3) According to the intake requirements, the two-dimensional projection shape 6 of the inlet of the middle inner contraction air inlet is designed. In the reference flow field designed and solved in step (2), the streamline is tracked according to the leading edge capture line 7 of the middle inner contraction air inlet, and the compression line 8 obtained by the streamline tracking of the middle inner contraction air inlet is obtained. The line defines the compression surface 9 of the middle inner contraction air inlet. The position, direction, pressure and other parameters of the streamline can be recorded during the tracking process. Then, the side of the air inlet is further tracked according to the two-dimensional projection shape of the designed inlet. The generated inlet profile is modified to ensure a smooth flow field transition and meet aerodynamic performance requirements. After the modification, the shoulder profile 10 of the central inward-contracting inlet is straightened to obtain the isolation section 11 of the central inward-contracting inlet and the outlet 12 of the isolation section of the central inward-contracting inlet, ensuring that the outlet 12 of the isolation section of the central inward-contracting inlet meets the design requirements (such as total pressure recovery and flow field uniformity). The modified central inward-contracting inlet is installed upside down on the inner waverider forebody of the waverider forebody.

[0035] (4) Designing an outer inner contracting air inlet: using the incoming flow after pre-compression of the outer waverider front 2 corresponding to the outer contracting flow field of the double waverider front as the incoming flow design parameter of the outer inner contracting air inlet, taking the pre-compressed shock wave as the incident shock wave, and using the curved shock wave control equation given in step (2) to solve the reference flow field of the outer inner contracting air inlet;

[0036] (5) According to the air intake requirements, the inlet two-dimensional projection shape 14 of the outer inner contraction air inlet is designed. In the reference flow field designed and solved in step (4), the streamline is traced according to the leading edge capture line 15 of the outer inner contraction air inlet to obtain the compression line 16 obtained by the streamline tracing of the outer inner contraction air inlet. The line defines the compression surface 17 of the outer inner contraction air inlet. Then, according to the designed inlet two-dimensional projection shape 14 of the inlet, the side surface and bottom surface of the air inlet are obtained by streamline tracing in the reference flow field. After the generated air inlet surface is modified, the shoulder line 18 of the outer inner contraction air inlet is straightened to obtain the isolation section 19 of the outer inner contraction air inlet and the isolation section outlet 20 of the outer inner contraction air inlet. The air inlet is installed upside down at the forebody, and the outer inner contraction air inlets are symmetrically arranged on both sides of the outer waverider forebody.

[0037] The advantage of the integrated design approach for three inlets, which incorporates dual waverider forebody elements, is that while ensuring the dual waverider forebody elements and the central, inwardly contracting inlet meet waveriding characteristics, the outer portion can also capture the pre-compressed flow from the outer waverider forebody elements based on air intake requirements and total pressure recovery. This not only compensates for insufficient air intake or weak shock wave capture in the central inlet, but also improves stability during actual flight. Furthermore, the three-inlet integrated design approach, which incorporates dual waverider forebody elements, utilizes non-uniform inlet flow as its design condition for all three inlets, significantly reducing the constraints imposed by the inlets on forebody design and providing a new approach for integrated airframe inlet design.

[0038] The central and outer inward-converging inlet ducts are mounted in an inverted position on the double-waverider forebody, ensuring that the geometry and aerodynamic characteristics of the inlet and forebody match. CFD software is used to numerically simulate the entire system to verify that the aerodynamic performance of the inlet meets design requirements. Particular attention is paid to key indicators such as total pressure recovery, flow coefficient, and flow field uniformity. Based on the numerical simulation results, the inlet design parameters are fine-tuned or optimized to improve overall performance.

[0039] According to the design conditions, the present invention provides a double waverider front with an integrated internal / external flow aerodynamic design, as well as a central inward-contracting air inlet and two symmetrical outer inward-contracting air inlets arranged in parallel along the span direction, wherein the central inward-contracting air inlet adopts a three-dimensional inward-contracting axisymmetric reference flow field for streamline tracking design, and the design parameters of the central inward-contracting air inlet reference flow field are derived from the shock wave surface of the central inward-contracting air inlet; the outer symmetrical inward-contracting air inlet also adopts a three-dimensional inward-contracting axisymmetric reference flow field for streamline tracking design, but the difference is that the design condition of the outer inward-contracting air inlet reference flow field is the non-uniform incoming flow at the inlet entrance of the outer inward-contracting air inlet, and the non-uniform incoming flow is the airflow pre-compressed by the outer waverider fronts on both sides. The aerodynamic coupling of the inner contracting baseline flow field of the inner waverider front and the outer contracting flow field of the outer waverider front allows both the front airframe and the lower surface of the central contracting inlet to maintain waveriding characteristics, maintaining overall aerodynamic performance. The arrangement of two symmetrical outer contracting inlets not only increases the captured flow but also further compresses the incoming flow, enhancing the aerodynamic performance and stability of the airframe. This design approach provides a new approach to the integrated design of dual waverider fronts and multiple inlets. Experiments have demonstrated that the present invention achieves the design requirements of a high contraction ratio, high total pressure recovery, and a large capture area for the airframe / inlet integration.

[0040] The above embodiments are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. The three-inlet integrated design method considering the double-rider wavefront is characterized by The following steps are involved: (1) Design of the double-rider wavefront: Design the reference flow field of the double-rider wavefront, give the bottom projection line of the leading edge line of the double-rider wavefront, and perform streamline tracing in the reference flow field to generate the lower surface of the double-rider wavefront; (2) Design of the central inward contraction inlet: Based on the shock wave surface design of the inner waverider front of the double waverider front, the three-dimensional central inward contraction inlet reference flow field is solved. (3) Designing a two-dimensional projection shape of the outlet of the three-dimensional central inward contraction air inlet according to the air intake requirements, performing streamline tracking in the three-dimensional inward contraction reference flow field in step (2), obtaining the profile of the three-dimensional central inward contraction air inlet, and inverting the air inlet after modification; (4) Design of the outer inner contraction inlet: Based on the non-uniform incoming flow after the outer waverider front of the double waverider front is pre-compressed, the three-dimensional outer inner contraction inlet reference flow field is solved; (5) According to the air intake requirements, the two-dimensional projection shape of the three-dimensional outer inner contraction air intake duct outlet is designed, and streamlines are tracked in the three-dimensional inner contraction reference flow field in step (4) to obtain the profile of the three-dimensional outer inner contraction air intake duct, and the air intake duct is inverted after modification.

2. The three-inlet integrated design method considering the double-rider wavefront as claimed in claim 1 is characterized in that In step (2), the incoming flow at the entrance of the designed three-dimensional central inward contraction air inlet is non-uniform, and is the shock wave surface of the inner wave rider front of the double wave rider front. The shock wave surface is first discretized into an incident shock wave, and the outflow parameters are solved using the curved shock wave theory to design a reference flow field, and then the profile of the air inlet is generated in the reference flow field.

3. The three-inlet integrated design method considering the double-rider wavefront as claimed in claim 1 is characterized in that In step (4), the inlet flow of the designed three-dimensional outer inner contraction air inlet is non-uniform, which is the airflow after the outer wave rider front of the double wave rider front is pre-compressed. The parameters of the outflow are first solved using the bending shock wave theory, and then the reference flow field of the air inlet is designed and generated based on the solved parameters.

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