An integrated design method for the layout of four circumferential air inlets on the forebody of a conical aircraft

Abstract

The present invention relates to an integrated design method for the layout of four circumferential air inlets of a conical aircraft forebody, comprising the following steps: (1) designing incoming flow conditions and a conical aircraft forebody; (2) designing a three-dimensional inward contraction basic flow field at four circumferential positions according to the conical aircraft forebody obtained in step (1); (3) designing a three-dimensional inward contraction air inlet inlet profile based on the generatrix of the conical aircraft forebody; (4) discretizing the three-dimensional inward contraction air inlet inlet profile, and obtaining an air inlet compression profile by performing streamline tracing in the inward contraction basic flow field according to geometric relationships; (5) completing the integrated design of the layout of four circumferential air inlets of a conical aircraft forebody through geometric modification. While maintaining the advantages of the conical aircraft forebody, the present invention carries out the design of a three-dimensional inward contraction air inlet at four circumferential positions, thereby introducing new ideas for the design of the aircraft forebody and the three-dimensional inward turning air inlet.

Description

Technical Field

[0001] The invention relates to the technical field of integrated design of a forebody and an air inlet, and in particular to an integrated design method for the layout of four circumferential air inlets on a forebody of a conical aircraft. Background Art

[0002] Air-breathing propulsion has long been considered the preferred propulsion system in the design and development of hypersonic vehicles because it can provide high specific impulse for hypersonic flight. A large number of studies have shown that the key to achieving near-space flight lies in the integrated design of the aircraft body and the propulsion system, among which the most critical and difficult problem is the integrated design of the aircraft forebody and the air inlet. Internationally, Frederick Ferguson et al. completed the integrated design of the aircraft body and the two-dimensional air inlet based on the wedge-guided waverider theory. This method was carried out by analyzing the coupling problem between the wedge-guided waverider and the air inlet under plane flow conditions. In addition, based on the tangent cone-guided waverider theory, Naruhisa Takashima et al. proposed an integrated design that achieves good coupling between the external flow tangent waverider and the internal flow two-dimensional air inlet. In China, You Yancheng et al. have deeply studied the waverider theory and applied it to the internal contraction flow, and proposed a double waverider theory method that is applicable to both the aircraft body and the three-dimensional internal contraction air inlet, solving the problem of integration of hypersonic external flow and internal flow. It can be seen that the current integrated solutions for hypersonic vehicles mostly focus on the matching of the waverider forebody and the air inlet. However, although the waverider vehicle has good design point performance, its shortcomings are also obvious, mainly in terms of volume ratio, angle of attack characteristics, and non-design point working performance.

[0003] The conical aircraft has been given special attention in the aerodynamic design of aircraft and missiles due to its simple structure, large volume ratio and good angle of attack characteristics. Many scholars have studied the curved cone configuration aircraft. In 1979, Frank proposed a submandibular air intake layout with air intake under the head of the curved cone missile body, and named it ASLAM. The air intake in this scheme is essentially a part of the axisymmetric air intake, so there is a phenomenon that the compression efficiency is compared with the three-dimensional inward contraction air intake. Because of its advantages such as high compression efficiency and good flow capture characteristics, the three-dimensional inward contraction air intake has received extensive attention in the design of the air intake system in recent years. The US "Hypersonic Strike Weapon (HSSW)" released by Lockheed Martin will also adopt the aerodynamic layout of a conical external compression forebody plus a three-dimensional inward rotation air intake in the abdomen, taking into account the advantages of the conical aircraft and the three-dimensional inward contraction air intake. Therefore, developing a forebody / inlet integrated design method that can simultaneously exert the excellent performance of the conical aircraft and the three-dimensional inward contraction air intake is a key issue that needs to be solved urgently. Since the conical aircraft is a conical or curved cone configuration, the aircraft must have an axisymmetric property. Therefore, this patent proposes to adopt a layout of four circumferential air inlets to achieve an integrated design of the conical aircraft front body and the three-dimensional inward-retracting air inlet. Summary of the invention

[0004] The problem to be solved by the present invention is to provide an integrated design method for the layout of four circumferential air inlets on a conical aircraft forebody, while maintaining the advantages of the conical aircraft forebody, carrying out the design of three-dimensional inward-retracting air inlets at four circumferential positions, thereby introducing new ideas for the design of the aircraft forebody and the three-dimensional inward-turning air inlets.

[0005] The technical solution provided by the present invention to solve the above problems is: a method for designing an integrated layout of four circumferential air inlets on a conical aircraft forebody, the method comprising the following steps:

[0006] (1) Design the incoming flow conditions and the conical vehicle forebody;

[0007] (2) designing a three-dimensional internal contraction basic flow field at four circumferential positions according to the conical aircraft forebody obtained in step (1);

[0008] (3) Based on the generatrix of the conical vehicle front body, design the inlet profile of the three-dimensional inward-contracting inlet;

[0009] (4) discretizing the inlet profile of the three-dimensional inward-contracting inlet duct, and tracing the streamlines in the inward-contracting basic flow field according to the geometric relationship to obtain the compression profile of the inlet duct;

[0010] (5) The integrated design of the four circumferential air inlet layout of the conical aircraft forebody is completed through geometric modification.

[0011] Preferably, the incoming flow condition in step (1) is the design working condition of the aircraft. The generatrix of the conical aircraft forebody adopts a cubic curve, and the coefficients of the cubic curve are determined according to four parameters, which are the coordinates of the starting point and the end point and the slope. After obtaining the generatrix, it is rotated 360° around the axis to obtain the conical aircraft forebody.

[0012] Preferably, in step (2), the inward contraction basic flow field is arranged in an axisymmetric manner on four circumferential sections of the conical aircraft forebody, and the section angles are 0°, 90°, 180°, and 270°, respectively. The inward contraction basic flow field is an axisymmetric flow field, and its rotation axis is located inside the conical aircraft forebody. The flow field is composed of the rotation axis, compression profile, incident shock wave, and reflected shock wave.

[0013] Preferably, the three-dimensional inward-contracting inlet inlet profile in step (3) consists of two parts, one part is the intersection line of the incident shock wave of the three-dimensional inward-contracting basic flow field and the surface of the conical aircraft front body, and the other part is a custom part. The inlet area of ​​the inlet can be determined according to the flow demand, and then the three-dimensional inward-contracting inlet inlet profile is determined.

[0014] Preferably, in step (4), a series of discrete points are obtained by discretizing the three-dimensional inlet profile, and according to the radius from each discrete point to the axis of rotation, corresponding positions are taken in the basic flow field obtained in step (3) for streamline tracing, and the obtained series of streamlines are arranged circumferentially in three dimensions to obtain the inlet compression surface.

[0015] Preferably, the geometric modification in step (5) mainly includes stretching the outlet profile of the three-dimensional inward-contracting air inlet compression surface in a straight line along the x-direction to obtain an isolation section; and stretching the customized part of the inlet profile of the three-dimensional inward-contracting air inlet in a straight line along the x-direction to obtain an external three-dimensional inward-contracting air inlet, thereby completing the design of the entire integrated solution.

[0016] Compared with the prior art, the advantages of the present invention are: the integrated configuration of the circumferential four-inlet layout of the conical aircraft forebody generated by the present invention using the design method can introduce new design ideas for the integrated design of the conical aircraft and the propulsion system. The design method can realize the integrated design of the aircraft and multiple propulsion systems, thereby significantly improving the flight capability of the hypersonic conical aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 It is a geometrical diagram of the forebody of a conical aircraft.

[0019] Figure 2 It is a schematic diagram of the matching between the three-dimensional inward contraction basic flow field and the conical aircraft forebody.

[0020] Figure 3 It is a cross-sectional view of the design of the inlet profile of the three-dimensional inward-contracting air intake.

[0021] Figure 4 This is a streamline tracing diagram.

[0022] Figure 5 It is a schematic diagram of the integrated configuration of four circumferential air inlets on the forebody of a conical aircraft.

[0023] Figure 6 It is a schematic diagram of the integrated configuration of four circumferential air inlets on the forebody of a conical aircraft with an air inlet cover.

[0024] The marks in the figure are: 1 represents the forebody of the conical aircraft, 2 represents the starting point of the mother line of the forebody of the conical aircraft, 3 represents the end point of the mother line of the forebody of the conical aircraft, 4 represents the rotation axis of the three-dimensional inward contraction basic flow field, 5 represents the compression profile of the three-dimensional inward contraction basic flow field, 6 represents the inlet of the three-dimensional inward contraction basic flow field, 7 represents the outlet of the three-dimensional inward contraction basic flow field, 8 represents the incident shock wave of the three-dimensional inward contraction basic flow field, 9 represents the reflected shock wave of the three-dimensional inward contraction basic flow field, 10 represents the custom part of the inlet profile of the three-dimensional inward contraction air intake, 11 represents the intersection line part of the inlet profile of the three-dimensional inward contraction air intake, 12 represents the discrete points of the inlet profile of the custom part, 13 represents the discrete points of the inlet profile of the intersection line part, 14 represents the radius from the discrete point to the rotation axis, 15 represents the streamline, 16 represents the compression surface of the three-dimensional inward contraction air intake, 17 represents the outlet profile of the compression surface of the three-dimensional inward contraction air intake, 18 represents the isolation section, 19 represents the outlet profile of the isolation section, and 20 represents the outer cover of the three-dimensional inward contraction air intake. DETAILED DESCRIPTION

[0025] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0026] The main implementation steps of the integrated design method for the circumferential four-inlet layout of the conical aircraft forebody include:

[0027] (1) Design the incoming flow conditions and the conical aircraft forebody 1. The incoming flow conditions are the aircraft design conditions. The generatrix of the conical aircraft forebody 1 is generated by a cubic curve, and the coefficients of the cubic curve are determined according to four parameters, which are the coordinates and slopes of the starting point 2 and the end point 3 of the conical aircraft forebody generatrix. After obtaining the generatrix, rotate it 360° around the axis to obtain the conical aircraft forebody 1.

[0028] (2) According to the conical aircraft forebody 1 obtained in step (1), a three-dimensional inward contraction basic flow field is designed at four circumferential positions. The three-dimensional inward contraction basic flow field is arranged in an axisymmetric manner at four circumferential sections of the conical aircraft forebody 1, and the section angles are 0°, 90°, 180°, and 270°, respectively. Figure 2 For the convenience of demonstration, only the inward contraction basic flow field at two positions of 90° and 270° is shown. The inward contraction basic flow field is an axisymmetric flow field, and the three-dimensional inward contraction basic flow field rotation axis 4 is located inside the conical aircraft forebody 1. The flow field is composed of the three-dimensional inward contraction basic flow field rotation axis 4, the three-dimensional inward contraction basic flow field compression line 5, the three-dimensional inward contraction basic flow field inlet 6 and the three-dimensional inward contraction basic flow field outlet 7.

[0029] (3) Based on the generatrix of the conical aircraft forebody 1, the three-dimensional inward-contracting air inlet inlet profile is designed. The three-dimensional inward-contracting air inlet inlet profile consists of two parts, one part is the intersection line of the three-dimensional inward-contracting basic flow field incident shock wave 8 and the surface of the conical aircraft forebody 1, namely, the three-dimensional inward-contracting air inlet inlet profile intersection line part 11, and the other part is a custom part. The inlet area can be determined according to the flow demand, and then the three-dimensional inward-contracting air inlet inlet profile custom part 10 is determined.

[0030] (4) Discretize the custom part 10 of the inlet profile of the three-dimensional inward contraction air intake duct and the intersection line part 11 of the inlet profile of the three-dimensional inward contraction air intake duct, and select the same radius from the discrete point to the rotation axis in the three-dimensional inward contraction basic flow field to determine the geometric relationship between the discrete points of the inlet profile and the three-dimensional inward contraction basic flow field. The inlet profile discrete points include the custom part inlet profile discrete points 12 and the intersection line part inlet profile discrete points 13. Then, streamline tracing is performed between the incident shock wave 8 of the three-dimensional inward contraction basic flow field and the reflected shock wave 9 of the three-dimensional inward contraction basic flow field to obtain streamline 15. The obtained series of streamlines are arranged circumferentially in three dimensions to obtain the three-dimensional inward contraction air intake duct compression surface 16.

[0031] (5) The integrated design of the four circumferential air inlet layout of the front body of the conical aircraft is completed through geometric modification. The geometric modification mainly includes stretching the outlet profile 17 of the three-dimensional inward-contracting air inlet compression profile along the x-direction to obtain the isolation section 18 and the isolation section outlet profile 19; stretching the custom part 10 of the three-dimensional inward-contracting air inlet inlet profile along the x-direction to obtain the three-dimensional inward-contracting air inlet cover 20, thereby completing the design of the entire integrated solution.

[0032] This integrated design method for the layout of four circumferential air inlets on the conical aircraft forebody maintains the advantages of the conical aircraft forebody and the three-dimensional inward-retracting air inlets, while carrying out the design of three-dimensional inward-retracting air inlets at four positions on the circumference of the conical aircraft forebody, thereby introducing new ideas for the design of the aircraft forebody and the three-dimensional inward-turning air inlets.

[0033] The beneficial effect of the present invention is that the integrated configuration of the circumferential four-inlet layout of the front body of the conical aircraft generated by the present invention using the design method can introduce new design ideas for the integrated design of the conical aircraft and the propulsion system. The design method can realize the integrated design of the aircraft and multiple propulsion systems, thereby significantly improving the flight capability of the hypersonic conical aircraft.

[0034] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing an integrated layout of four circumferential air inlets on a conical aircraft forebody, characterized in that: The method comprises the following steps: (1) Designing incoming flow conditions and a conical aircraft forebody; the incoming flow conditions in step (1) are the aircraft design conditions; the generatrix of the conical aircraft forebody adopts a cubic curve, and the coefficients of the cubic curve are determined according to four parameters, which are the coordinates of the starting point and the end point and the slope; after obtaining the generatrix, rotating it around the axis by 360° obtains the conical aircraft forebody; (2) According to the conical aircraft forebody obtained in step (1), a three-dimensional inward contraction basic flow field is designed at four circumferential positions; in step (2), the inward contraction basic flow field is arranged in an axisymmetric manner at four circumferential sections of the conical aircraft forebody, and the section angles are 0°, 90°, 180°, and 270° respectively; the inward contraction basic flow field is an axisymmetric flow field, and its rotation axis is located inside the conical aircraft forebody; the flow field is composed of the rotation axis, the compression line, the incident shock wave, and the reflected shock wave; (3) Designing a three-dimensional inward-contracting inlet profile based on the generatrix of the front body of the conical aircraft; the three-dimensional inward-contracting inlet profile in step (3) consists of two parts, one part is the intersection line of the incident shock wave of the three-dimensional inward-contracting basic flow field and the surface of the front body of the conical aircraft, and the other part is a custom part. The inlet area of ​​the inlet can be determined according to the flow demand, and then the three-dimensional inward-contracting inlet profile is determined; (4) discretizing the inlet profile of the three-dimensional inward-contracting inlet duct, and performing streamline tracing in the inward-contracting basic flow field according to the geometric relationship to obtain the compression profile of the inlet duct; in step (4), discretizing the custom part of the inlet profile of the three-dimensional inward-contracting inlet duct and the intersection line part of the inlet profile of the three-dimensional inward-contracting inlet duct, and selecting the same radius from the discrete point to the rotation axis in the three-dimensional inward-contracting basic flow field to determine the geometric relationship between the discrete points of the inlet profile and the three-dimensional inward-contracting basic flow field, the inlet profile discrete points include the custom part of the inlet profile discrete points and the intersection line part of the inlet profile discrete points, then performing streamline tracing between the incident shock wave of the three-dimensional inward-contracting basic flow field and the reflected shock wave of the three-dimensional inward-contracting basic flow field to obtain the streamline, and arranging the obtained series of streamlines circumferentially in three dimensions to obtain the compression profile of the three-dimensional inward-contracting inlet duct; (5) The integrated design of the layout of the four circumferential air inlets of the forebody of the conical aircraft is completed by geometric modification; the geometric modification in step (5) includes stretching the outlet profile of the compression profile of the three-dimensional inward-contracting air inlet duct in a straight line along the x-direction to obtain an isolation section; and stretching the customized part of the inlet profile of the three-dimensional inward-contracting air inlet duct in a straight line along the x-direction to obtain the three-dimensional inward-contracting air inlet duct externalization, thereby completing the design of the entire integrated solution.

Images