Three-air-inlet-channel integrated design method considering double waverider precursors

Abstract

The invention discloses a three-air-inlet-channel integrated design method considering double waverider front bodies, and relates to integrated design of front bodies / air inlet channels of hypersonic flight vehicles. According to design conditions, double waverider front bodies of internal / external flow integrated pneumatic design, a middle internal contraction air inlet channel and two symmetrical outer side internal contraction air inlet channels are provided, and the middle internal contraction air inlet channel is designed in a three-dimensional internal contraction axial symmetry reference flow field streamline tracking mode. The streamline tracking design is also carried out on the inner contraction air inlet channel which is symmetrical on the outer side by adopting a three-dimensional inner contraction axial symmetry reference flow field, and the inner contraction reference flow field of the inner waverider precursor and the outer contraction flow field of the outer waverider precursor are pneumatically coupled, so that the waverider characteristics of a precursor machine body and the lower surface of the middle inner contraction air inlet channel are kept; the whole aerodynamic performance is maintained, the other two symmetrical outer-side internal contraction air inlet channels are arranged, on the basis that the capture flow is improved, incoming flow is further compressed, and the aerodynamic performance and stability of a machine body are improved; and efficiency and performance requirements are considered.

Description

Technical Field

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

[0002] As a near-space propulsion method with great potential, hypersonic air-breathing propulsion has attracted much attention in the aerospace field. Due to the complexity of hypersonic flow, the integration of airframe / propulsion system is one of the key issues to be solved in hypersonic flight, and the key lies in the integration of airframe / inlet. The integrated design of the two requires an optimal inlet design that can meet high compression ratio, high total pressure recovery and large capture area while ensuring the lift-to-drag ratio of the hypersonic aircraft.

[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.), waverider with high lift-to-drag ratio has been widely used in the integrated design of air-breathing hypersonic aircraft. At present, most of the inlets are designed based on uniform incoming flow, resulting in the early integrated design research focusing on the forebody of the aircraft, that is, setting a local plane in front of the inlet entrance for rectification. In order to make the waverider forebody generate a relatively uniform incoming flow, the early waverider forebody was generated based on the wedge flow field. 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. Due to the limitation of the plane shock wave, this scheme has the problems of too large anhedral angle and low volume ratio. 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 field. Jones (Jones KD, Sobieczy H, Seebass AR, et al. Waverider design for generalized shock geometries [J]. Journal of Spacecraft The occlusive waverider principle proposed by

[1993] (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 broaden the research direction of the integrated design of the aircraft.

[0004] In order to improve the adaptability of the inward turning inlet to the non-uniform incoming flow, an integrated design method of the common reference flow field of the airframe inlet is proposed. The main design methods include the osculating inward turning cone waverider / inlet (OICWl) design methods and experiment a! study R. AIAA-2012-5810, 2012. proposed by He Xuzhao. By designing the axisymmetric inward contraction reference flow field, the guiding line shape of the waverider forebody is given and the waverider forebody configuration is tracked. Then, the inlet lip line shape is given at the axial position of the overflow port and the inlet profile is tracked. Thus, the flow field at the inlet entrance matches the pre-compression flow field of the forebody; You Y C, Zhu CX, Guo J L. Duel wave rider concept for the integration of hypersonic inward-turning inlet and airframe forebody, AIAA Pa per 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 shock waves of the two flow fields smoothly transition in the span direction. An inner waverider inlet matching the inner deflection flow field is designed downstream of the inner deflection flow field. This method flexibly connects the inner / outer deflection flow fields so that the lift is combined with the pre-contracted forebody profile. Li Yiqing et al. (Li Yiqing. Research on integrated design method of hypersonic internal and external flows based on double waverider theory [D]. Xiamen University, 2018.) further developed a dual-channel integrated design method based on this design to improve the contraction efficiency of the inlet.

[0005] At present, the design of hypersonic vehicle inlets is basically simplified by uniform flow, 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 flow caused by the double-rider wave forebody boundary layer and the leading edge curved shock wave, the design of an inlet that can actively adapt to the non-uniform flow is more conducive to the research and development of hypersonic forebody / inlet integration. Summary of the invention

[0006] The purpose of the present invention is to provide a three-inlet integrated design method taking into account the double-rider wavefront in order to solve the above-mentioned 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 middle inwardly contracting air inlet and two outer symmetrical inwardly 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 middle inwardly contracting air inlet and the outer inwardly 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 waverider front: Design the reference flow field of the double waverider front, give the bottom projection line of the leading edge line of the double waverider front, and perform streamline tracing in the reference flow field to generate the lower surface of the double waverider front;

[0010] (2) Design of the central inward-contracting inlet: Based on the shock wave surface design of the inner waverider front of the double waverider front, the three-dimensional central inward-contracting inlet reference flow field is solved;

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

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

[0013] (5) According to the air intake requirement, the two-dimensional projection shape of the three-dimensional outer-inward contracting air intake duct entrance is designed, and streamlines are traced in the three-dimensional inward contracting reference flow field in step (4) to obtain the profile of the three-dimensional outer-inward contracting air intake duct, and the air intake duct is inverted after modification.

[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 waverider front of the double waverider 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 inlet is also non-uniform. It is the airflow after pre-compression of the outer waverider front of the double waverider front. Similarly, the parameters of the outflow must be solved using the curved shock wave theory, and then the reference flow field of the inlet is generated based on the solved parameters.

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

[0017] The design method for generating a three-inlet design considering the double waverider forerunner is used to take into account both the flow direction and the lateral dimensions. First, the double waverider forerunner reference flow field along the flow direction adopts a full waverider design with internal / external flow integration to achieve aerodynamic coupling between the forerunner and the middle inlet, reduce the aerodynamic interference of the fuselage, and ensure the waverider characteristics; secondly, in the three inlets arranged in the span direction, the inner contraction reference flow field of the middle inner contraction inlet is coupled with the outer contraction reference flow field of the forerunner to achieve an integrated design of internal and external flows; the outer inner contraction inlet reference flow field is designed according to the pre-contracted airflow of the outer waverider forerunner to ensure full flow capture of the outer inlet, and achieve the design requirements of high contraction rate, high total pressure recovery and large capture area of ​​fuselage / inlet integration. The present invention fully considers the complex flow field characteristics of the double waverider forerunner and the performance requirements of the inlet. Through the combination of streamline tracing and reference flow field solution, an inlet that meets the performance indicators can be accurately designed. 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 schematic 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-rider wavefront.

[0020] Figure 3 It is a two-dimensional projection schematic diagram of the inlet and outlet cross-sections of the central inner contraction air inlet duct.

[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 schematic diagram of the inlet and outlet cross-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 contracting 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 numerals: 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 entrance 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 in conjunction with the accompanying drawings.

[0027] like Figures 1 to 7 As shown, in the three-inlet integrated design method considering the double waverider front, the double waverider front 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 inner contraction air inlet is composed of a lip 5 of the central inner contraction air inlet, a leading edge capture profile 7 of the central inner contraction air inlet, a compression profile 9 of the central inner contraction air inlet, a shoulder profile 10 of the central inner contraction air inlet, an isolation section 11 of the central inner contraction air inlet, and an isolation section outlet 12 of the central inner contraction air inlet; the outer three-dimensional inner contraction air inlet is composed of a lip 13 of the outer inner contraction air inlet, a leading edge capture profile 15 of the outer inner contraction air inlet, a compression profile 17 of the outer inner contraction air inlet, a shoulder profile 18 of the outer inner contraction air inlet, an isolation section 19 of the outer inner contraction air inlet, and an isolation section outlet 20 of the outer inner 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 waverider front: According to the reference flow field of the internal flow / plane and external flow aerodynamic coupling obtained by solving the design requirements, the bottom projection profile of the leading edge profile of the double waverider front is given, and the bottom projection profile of the discrete leading edge profile is used to obtain the leading edge line for 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 waverider front, and the shock wave 4 generated by the outer contraction flow field defines the boundary of the outer waverider front. The inner waverider front 1 corresponding to the inner contraction flow field and the outer waverider front 2 corresponding to the outer contraction flow field of the double waverider front are obtained.

[0030] Specifically, the design conditions and expected performance indicators such as total pressure recovery and flow coefficient of 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, wall conditions, etc., and solve to obtain a stable reference flow field. According to the design requirements, the bottom projection of the leading edge profile of the double waverider front is preliminarily set. In the reference flow field, the bottom projection of the leading edge profile is discretized, and streamline tracking is started at each discrete point. The direction of streamline tracking should be along the incoming flow direction until the streamline leaves the calculation domain or reaches the predetermined tracking length. According to the results of streamline tracking, the geometric shapes of the inner waverider front 1 corresponding to the inner contraction flow field and the outer waverider front 2 corresponding to the outer contraction flow field are generated. The inner waverider front should be close to the shock wave surface in the inner flow field, while the outer waverider front is designed according to the shock wave and compression effect in the outer flow field.

[0031] (2) Designing a central inner contraction 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 inlet is solved using the curved 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 inlet; the curved shock wave control equation is as follows:

[0032]

[0033] Among them, 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 airflow angle along streamline.

[0034] (3) According to the air intake requirements, a two-dimensional projection shape 6 of the inlet of the middle inner contraction air intake is designed. In the reference flow field designed and solved in step (2), streamline tracking is performed according to the leading edge capture profile 7 of the middle inner contraction air intake to obtain a compression profile 8 obtained by the streamline tracking of the middle inner contraction air intake. The profile defines the compression profile 9 of the middle inner contraction air intake. During the tracking process, the position, direction, pressure and other parameters of the streamline can be recorded. Then, according to the designed two-dimensional projection shape of the inlet, the side of the air intake is further tracked. The generated inlet profile is processed by the face surface and the bottom profile to ensure a smooth transition of the flow field and meet the aerodynamic performance requirements; after the processing, the shoulder profile 10 of the middle inner contraction inlet is straightly stretched to obtain the isolation section 11 of the middle inner contraction inlet and the outlet 12 of the isolation section of the middle inner contraction inlet, ensuring that the outlet 12 of the isolation section of the middle inner contraction inlet meets the design requirements (such as total pressure recovery, flow field uniformity, etc.), and the modified middle inner contraction inlet is inverted and installed at the inner waverider forebody of the waverider forebody;

[0035] (4) Designing an outer inner contracting inlet duct: using the pre-compressed incoming flow of the outer waverider front body 2 corresponding to the outer contracting flow field of the double waverider front body as the incoming flow design parameter of the outer inner contracting inlet duct, 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 inlet duct;

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

[0037] The advantage of the integrated design method of three air inlets considering double waverider forebody is that while ensuring that the double waverider forebody and the middle inner contraction air inlet meet the "waverider" characteristics, the pre-compressed incoming flow of the outer waverider forebody can be captured on the outside according to the air intake demand and total pressure recovery requirements, which can not only make up for the insufficient air intake of the middle air inlet or the weak shock wave capture, but also improve the stability in actual flight. In addition, in the integrated design method of three air inlets considering double waverider forebody, all three air inlets use non-uniform incoming flow as the design condition of the air inlet, which greatly reduces the restrictions of the air inlet on the forebody design and provides a new idea direction for the integrated design of the air inlet of the fuselage.

[0038] The central inward-contracting inlet and the outer inward-contracting inlet are installed upside down on the double waverider forebody to ensure that the geometry and aerodynamic characteristics of the inlet match those of the forebody. The entire system is numerically simulated using CFD software to verify whether the aerodynamic performance of the inlet meets the design requirements. Special attention is paid to key indicators such as total pressure recovery, flow coefficient, and flow field uniformity. Based on the numerical simulation results, the design parameters of the inlet are fine-tuned or optimized to improve the overall performance.

[0039] According to the design conditions, the present invention provides a double waverider front body with an integrated internal / external flow aerodynamic design, as well as a central inwardly contracting air inlet and two symmetrical outer inwardly contracting air inlets arranged in parallel along the span direction, wherein the central inwardly contracting air inlet adopts a three-dimensional inwardly contracting axisymmetric reference flow field for streamline tracking design, and the design parameters of the central inwardly contracting air inlet reference flow field are derived from the shock wave surface of the central inwardly contracting air inlet; the outer symmetrical inwardly contracting air inlet also adopts a three-dimensional inwardly contracting axisymmetric reference flow field for streamline tracking design, but the difference is that the design condition of the reference flow field of the outer inwardly contracting air inlet is the non-uniform incoming flow at the inlet entrance of the outer inwardly contracting air inlet, and the non-uniform incoming flow is the airflow pre-compressed by the outer waverider front bodies on both sides. The inner contraction reference flow field of the inner waverider front body is aerodynamically coupled with the outer contraction flow field of the outer waverider front body, so that the front body and the lower surface of the middle inner contraction air inlet can maintain the waveriding characteristics and maintain the overall aerodynamic performance. The other two symmetrical outer inner contraction air inlets are arranged. On the basis of increasing the captured flow, the incoming flow can be further compressed to improve the aerodynamic performance and stability of the body. This design method provides a new idea for the integrated design of double waverider front bodies and multiple air inlets. Experiments show that the present invention meets the design requirements of high contraction rate, high total pressure recovery and large capture area of ​​the body / air inlet integration.

[0040] The above embodiments are only preferred embodiments of the present invention and cannot 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 present invention.

Claims

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

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