A serially arranged dual inlet duct-precooler structure and its design method

Abstract

The present invention discloses a binary air inlet duct precooler structure, including two components, an air inlet duct and a precooler, and the air inlet duct and the precooler are arranged in series. The air inlet duct is characterized by a binary air inlet duct, including a contraction section and an expansion section. The air inlet duct contraction section is designed using the equal intensity wave distribution theory, and the air inlet duct expansion section includes a normal shock wave or an oblique shock wave train. The precooler is characterized by being located at the outlet of the air inlet duct expansion section and placed at a certain angle to the incoming flow. The precooler contains several rows of regularly arranged low-temperature heat exchange circular tubes, which can cool the airflow captured by the air inlet duct. The air inlet duct and the precooler are arranged in series, and the structure is relatively simple and highly feasible. The precooler is placed at an acute angle to the flow direction, which can increase the length of the tube bundle in the precooler and increase the heat exchange area, thereby achieving the purpose of reducing the temperature; at the same time, the vertical velocity of the tube bundle area in the precooler is reduced, which can alleviate the congestion of the flow field.

Description

Technical Field

[0001] The present invention relates to a serially arranged dual air inlet-precooler structure and a design method thereof, belonging to the technical field of hypersonic combined power. Background Art

[0002] At present, a single power system cannot meet the requirements of hypersonic vehicles such as a wide flow range and a wide range of altitude changes. The pre-cooled combined engine has become one of the research focuses due to its excellent performance and great potential development trend.

[0003] Precooled combined engines generally include air inlet, precooler, press, combustion chamber and turbine. The air inlet is one of the main components of the air-breathing combined propulsion system. Its design goal is to provide as much high-energy airflow as possible to the downstream propulsion system components with less flow loss. As one of the most critical components of the air-breathing combined propulsion system, the precooler uses a low-temperature medium to cool the incoming air, broaden the working envelope of the aircraft power system, and significantly improve the performance of the hypersonic engine.

[0004] The precooler cools the high-temperature airflow captured by the inlet to avoid excessive temperature in front of the compressor under high Mach number inlet conditions. However, due to the presence of the precooler, it will cause obstruction to the inlet, so the matching design of the inlet and precooler is particularly important. However, there is still a lack of research on the matching design of the binary inlet and precooler series layout. For example, how to meet the heat exchange effect while avoiding inlet flow congestion in the precooler structure size and arrangement method. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a binary inlet duct-precooler structure and design method with a fixed geometry and a design state of an incoming flow shock wave contacting the inlet, and utilizing a low-temperature heat exchange tube bundle to cool the incoming flow.

[0006] The present invention provides a dual air inlet duct-precooler structure with a serial layout, wherein the dual air inlet duct includes an air inlet duct compression section and an air inlet duct expansion section, the air flow outlet end of the air inlet duct expansion section is connected to the precooler air inlet, and the air flow direction of the precooler air inlet and the air inlet duct expansion section outlet end form an acute angle.

[0007] Furthermore, the precooler comprises a heat exchange tube bundle of circular tubes, and the tube bundles are arranged in a staggered pattern, wherein the tube bundle spacing and tube bundle diameter are kept fixed.

[0008] Further, the air intake duct compression section includes two parallel side panels, an air intake duct compression surface, an air intake duct shoulder, and an air intake duct lip cover;

[0009] The air intake duct compression surface, the air intake duct shoulder, and the air intake duct lip cover are all located between two parallel side panels; the air intake duct compression surface is designed by a three-stage isentropic compression method, the air intake duct compression surface is smoothly connected to the air intake duct shoulder, the air intake duct lip cover is arranged above the air intake duct shoulder, and the air intake duct shoulder, the air intake duct lip cover, and two parallel side panels form an air flow channel;

[0010] The airflow inlet end of the air intake expansion section is connected to the air intake shoulder, the air intake lip cover, and two parallel side panels to form an airflow channel.

[0011] Furthermore, the upper surface of the air inlet expansion section is a planar structure, and the lower surface is a curved surface;

[0012] The upper surface of the air inlet expansion section refers to the surface connected to the air inlet lip cover, and the lower surface of the air inlet expansion section refers to the surface connected to the air inlet shoulder.

[0013] Furthermore, the lower surface of the air inlet expansion section adopts an equal area gradient diffusion method, and arc transition treatment is adopted on both sides.

[0014] The present invention provides a design method for a serially arranged binary air inlet-precooler structure, the method is based on the serially arranged binary air inlet-precooler structure of the present invention, and the method comprises the following steps:

[0015] 1) Based on the binary internal contraction basic flow field, the equal intensity wave distribution theory is adopted to design a three-wave binary mixed compression inlet. The area where the compression surface of the inlet is located is the external compression section, which adopts a three-shock wave design. The area where the shoulder of the inlet is located is the internal compression section, which adopts an oblique shock wave compression;

[0016] 2) According to the airflow outlet area of ​​the inlet expansion section, the expansion section of the inlet duct is determined by adopting the equal area gradient pressure diffusion method;

[0017] 3) The precooler is arranged at the airflow outlet end of the air inlet expansion section and forms an acute angle with the airflow direction;

[0018] 4) The precooler contains multiple rows of regularly arranged low-temperature heat exchange tubes, and the tube bundle spacing and tube bundle diameter remain fixed.

[0019] Compared with the prior art, the beneficial effect of the present invention is that the inlet duct and the precooler are arranged in series, the structure is relatively simple, and the engineering feasibility is high. The precooler is placed at an acute angle to the flow direction, which can increase the length of the tube bundle in the precooler and increase the heat exchange area to achieve the purpose of reducing the temperature; at the same time, the vertical velocity of the tube bundle area in the precooler is reduced, which can alleviate the congestion of the flow field. In addition, the tube bundle spacing is set to a certain multiple of the tube bundle diameter, which comprehensively considers the heat exchange effect and the flow field congestion problem, and can meet the purpose of reducing the incoming flow temperature while the flow field is flowing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a three-dimensional schematic diagram of the dual inlet-precooler matching design;

[0021] Figure 2 It is a partial schematic diagram of the dual air intake duct;

[0022] Figure 3 It is a schematic diagram of the precooler heat exchange tube model;

[0023] Figure 4 It is a partial schematic diagram of the precooler heat exchange tube A.

[0024] Among them, 1. Inlet compression surface; 2. Inlet lip cover; 3. Side panel; 4. Inlet expansion section; 5. Precooler; 6. Hypersonic incoming flow; 7. Oblique shock wave; 8. Compression wave; 9. Expansion wave; 10. Heat exchange tube; 11. Inlet shoulder. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, a binary air inlet-precooler structure with a serial layout of the present invention comprises a binary air inlet and a precooler 5, wherein the binary air inlet and the precooler 5 are arranged in series;

[0027] The dual air intake duct includes an air intake duct compression section and an air intake duct expansion section, wherein the air intake duct compression section is used to decelerate and pressurize the incoming flow, and the air intake duct compression section includes two parallel side plates 3, an air intake duct compression surface 1, an air intake duct shoulder 11, and an air intake duct lip cover 2;

[0028] The air inlet compression surface 1, the air inlet shoulder 11, and the air inlet lip cover 2 are all located between two parallel side panels 3; the air inlet compression surface 1 adopts a three-stage isentropic compression design, the air inlet compression surface 1 is a three-section wedge surface, the air inlet compression surface 1 is smoothly connected to the air inlet shoulder 11, which is beneficial to increase the compression efficiency at the air inlet shoulder 11 and improve the low Mach number automatic overflow capability, the air inlet lip cover 2 is located above the air inlet shoulder 11, and the air inlet shoulder 11, the air inlet lip cover 2, and two parallel side panels 3 form an air flow channel;

[0029] The area where the air inlet compression surface 1 is located is the outer compression section, and the area where the air inlet shoulder 11 is located is the inner compression section;

[0030] When designing the position of the inlet lip 2, the reference Mach number is first selected, and the hypersonic incoming flow 6 forms an initial incident shock wave at the starting end of the inlet compression surface 1, and is affected by the inlet compression surface 1 to generate three oblique shock waves 7, which converge at the lip. The lip refers to the port position of the inlet lip 2. The port position is close to the inlet compression surface 1; the airflow is reflected near the lip, passes through the inlet shoulder 11, and enters the inlet expansion section;

[0031] The airflow inlet end of the air intake expansion section is connected to the air intake shoulder 11, the air intake lip cover 2, and the two parallel side panels 3 to form an airflow channel, and the airflow outlet end of the air intake expansion section is connected to the precooler 5;

[0032] The upper surface of the air inlet expansion section is a plane structure, and the lower surface adopts a pressure diffusion method with equal area gradient. The upper surface of the air inlet expansion section refers to the surface connected to the air inlet lip cover 2, and the lower surface of the air inlet expansion section refers to the surface connected to the air inlet shoulder 11. The area change near the inlet and outlet ends of the air inlet expansion section is relatively gentle, and the area change in the middle section is relatively large, which is more conducive to smooth transition of airflow and reduced loss;

[0033] The air inlet of the precooler 5 forms an acute angle with the airflow direction in the air inlet expansion section. The precooler 5 includes several rows of regularly arranged low-temperature heat exchange tubes, which cool the airflow captured by the air inlet in turn. The tube bundle spacing and tube bundle diameter are kept fixed. The wider the width of the air inlet of the precooler 5, the more round tubes there are. The air captured by the air inlet duct flows outside the round tube, and the low-temperature coolant flows inside.

[0034] A structure of a dual inlet duct-precooler arranged in series and a design method thereof, comprising the following steps:

[0035] 1) Based on the binary internal contraction basic flow field, the equal intensity wave distribution theory is adopted to design a three-wave binary mixed compression inlet. The outer compression section adopts three oblique shock waves, and the inner compression section adopts one oblique shock wave compression.

[0036] 2) According to the airflow outlet area of ​​the inlet expansion section, the expansion section profile of the inlet is determined by adopting the equal area gradient expansion method, and arc transition treatment is adopted on both sides of the expansion section.

[0037] 3) The precooler 5 is arranged at the airflow outlet end of the air inlet expansion section and is placed at an acute angle to the flow direction.

[0038] 4) The precooler 5 includes several rows of regularly arranged low-temperature heat exchange tubes, and the tube bundle spacing and tube bundle diameter remain fixed.

[0039] The main characteristics of the flow field include incident shock waves and reflected shock waves. After the airflow is heated by the inlet duct, it is cooled by the low-temperature heat exchange tube of the precooler 5, and its temperature decreases.

[0040] The present invention takes Mach number 6 as the design point and designs the following Figure 1 The dual inlet duct-precooler structure shown in the figure has an inlet duct lip height of 100 mm, wedge angles of 5.3°, 12.1°, and 19.2°, respectively. The inlet duct outlet height is 50 mm, the throat height is 14 mm, and the inlet duct aspect ratio is 6. Figure 2 The precooler 5 is placed at an angle of 10° to the air inlet duct, wherein the diameter of the round tube in the precooler 5 is 2 mm, the transverse pitch ratio perpendicular to the B direction is 2.5, and the longitudinal pitch ratio parallel to the B direction is 1.5. The figure contains 12 rows of heat exchange tubes, a total of 186 heat exchange tubes. Figure 3 Attached is the structural diagram of the precooler 5. Figure 4 It is a partial schematic diagram of the cryogenic heat exchange tube of the precooler 5. Under the condition of the incoming flow Mach number 6, the initial incident shock wave is formed at the inlet, and three oblique shock waves are generated under the influence of the inlet wedge surface, which intersect at the lip. The airflow is reflected near the lip to form compression wave 8 and expansion wave 9, and then enters the expansion section of the inlet. The airflow is cooled by the regularly arranged cryogenic heat exchange tubes in the precooler 5, achieving the effect of reducing the temperature while preventing the flow field from being blocked.

[0041] In addition, the present invention can also be designed with other tube row numbers and sizes, such as 30 tube rows and a longitudinal pitch ratio of 2. The above embodiments are only used to explain the present invention and cannot be used as a limitation of the present invention. Therefore, all implementation methods with the same design concept as the present invention are within the protection scope of the present invention.

Claims

1. A dual air intake duct-precooler structure arranged in series, characterized in that: The binary air inlet comprises an air inlet compression section and an air inlet expansion section, the air flow outlet end of the air inlet expansion section is connected to the air inlet of the precooler, and the air flow directions of the air inlet of the precooler and the outlet end of the air inlet expansion section form an acute angle; The air intake duct compression section includes two parallel side panels, an air intake duct compression surface, an air intake duct shoulder, and an air intake duct lip cover; The air intake duct compression surface, the air intake duct shoulder, and the air intake duct lip cover are all located between two parallel side panels; the air intake duct compression surface is designed by a three-stage isentropic compression method, the air intake duct compression surface is smoothly connected to the air intake duct shoulder, the air intake duct lip cover is arranged above the air intake duct shoulder, and the air intake duct shoulder, the air intake duct lip cover, and two parallel side panels form an air flow channel; The airflow inlet end of the air intake expansion section is connected to the air intake shoulder, the air intake lip cover, and the two parallel side panels to form an airflow channel; The upper surface of the air inlet expansion section is a flat structure, and the lower surface is a curved surface; The upper surface of the air inlet expansion section refers to the surface connected to the air inlet lip cover, and the lower surface of the air inlet expansion section refers to the surface connected to the air inlet shoulder; The lower surface of the inlet expansion section adopts an equal-area gradient diffusion method, and arc transition treatment is used on both sides.

2. According to claim 1, a dual air intake duct-precooler structure with a series layout is characterized in that: The precooler comprises heat exchange tube bundles, which are arranged in a staggered pattern, wherein the distance between the tube bundles and the diameter of the tube bundles are kept fixed.

3. A method for designing a dual inlet duct-precooler structure in series arrangement according to any one of claims 1 to 2, characterized in that: The steps include: 1) Based on the binary internal contraction basic flow field, the equal intensity wave distribution theory is adopted to design a three-wave binary mixed compression inlet. The area where the compression surface of the inlet is located is the external compression section, which adopts a three-shock wave design. The area where the shoulder of the inlet is located is the internal compression section, which adopts an oblique shock wave compression; 2) According to the airflow outlet area of ​​the inlet expansion section, the expansion section of the inlet duct is determined by adopting the equal area gradient pressure diffusion method; 3) The precooler is arranged at the airflow outlet end of the air inlet expansion section and forms an acute angle with the airflow direction; 4) The precooler contains multiple rows of regularly arranged low-temperature heat exchange tubes, and the tube bundle spacing and tube bundle diameter remain fixed.

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