Engine air inlet device with precooler and design method thereof

Abstract

The invention relates to the technical field of aero-engines, and discloses an engine air inlet device with a precooler and a design method thereof, and the engine air inlet device comprises a center cone casing, a diversion center cone, a precooling casing, a precooler assembly and an outlet reverse cone. According to the engine air inlet device, the precooler and the air inlet channel are designed in an integrated mode, the overall structure is compact, the overall complexity is low, and efficient air inlet precooling and low-loss flowing can be achieved; on the premise that the heat exchange requirement and the flow resistance requirement are met, the capillary tube bundle type precooler structure is adopted, and the weight is lighter; in addition, the pre-cooling casing is designed into a contraction flow channel, so that heat exchange between air and the internal pre-cooler assembly can be enhanced; an outlet reverse cone is designed at the position of an outlet of the central cone casing, so that airflow passing through the precooler assembly can be better discharged, and the problem of high back pressure of an inlet is relieved.

Description

Technical Field

[0001] The invention relates to the technical field of aviation engines and discloses an engine air intake device with a precooler and a design method thereof. Background Art

[0002] As aircraft speeds increase, the engine inlet faces a harsh aerodynamic and thermodynamic environment. Temperatures rise dramatically with increasing speed, increasing the heat load at the engine inlet. A precooler cools the high-temperature airflow captured by the inlet, but the independent design of conventional precoolers and inlets presents an aerodynamic and thermodynamic mismatch. This independent design disrupts the synergy between the airflow and the boundary layer within the inlet, significantly reducing the total pressure recovery coefficient and creating the risk of instability in localized low-speed zones.

[0003] At present, there are still many problems in the matching design research of the inlet duct and precooler layout. Existing technologies such as NASA's ramjet precooler, Japan's ATREX precooled engine and SABRE precooler engine have attempted to integrate the precooling system with the ramjet engine to optimize the integration level, but there are still problems such as large flow resistance and insufficient dynamic adjustment. Summary of the Invention

[0004] The purpose of the present invention is to provide an engine air intake device with a precooler and a design method thereof, which can achieve efficient intake air precooling and low-loss flow, enhance the heat exchange between air and internal precooler components, and better discharge the airflow passing through the precooler components, thereby alleviating the problem of high inlet back pressure.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0006] An engine air intake device with a precooler, comprising:

[0007] A central cone casing, wherein the inlet end of the central cone casing is connected to the outlet end of the air intake section, and a guide central cone is fixed in the central cone casing via a mounting support plate, with the cone tip of the guide central cone facing the incoming flow direction;

[0008] A pre-cooling casing, wherein the inlet end of the pre-cooling casing is coaxially fixedly connected to the central cone casing, and the diameter of the pre-cooling casing decreases smoothly along the airflow direction to form a contraction flow channel;

[0009] A precooler assembly, wherein the precooler assembly is mainly composed of a plurality of capillary tubes, the plurality of capillary tubes being evenly distributed along the circumference with the central axis of the precooling casing as the axis; a fluid cooling medium is used in the capillary tubes, and a gap for airflow is provided between two adjacent capillary tubes; an airflow channel for airflow from the intake section is formed between the precooler assembly and the precooling casing;

[0010] The outlet counter-cone is coaxially fixed to the end of the central cone away from the incoming flow direction, the large diameter starting end of the outlet counter-cone is located near the outlet end of the central cone casing, and the conical tip of the outlet counter-cone extends in the direction of airflow to a position near the outlet end of the pre-cooling casing.

[0011] Furthermore, the precooler assembly further includes an inlet branch and an outlet branch, and each of the capillary tubes is connected between the inlet branch and the outlet branch; the inlet branch and the outlet branch are both flexible hoses.

[0012] Furthermore, a plurality of mounting protrusions are circumferentially arranged near the outlet end of the pre-cooling casing, and the inlet branch and outlet branch corresponding to the capillary are respectively fixed on the mounting protrusions; each capillary is connected between the inlet branch and the outlet branch in a bent form.

[0013] Furthermore, it also includes a measuring casing and a transition section casing, one end of the transition section casing is coaxially fixedly connected to the outlet end of the pre-cooling casing, and the other end of the transition section casing is coaxially fixedly connected to the measuring casing through a floating casing; the transition section casing is used to introduce the airflow of the airflow channel into the measuring casing, and the floating casing is used to realize a movable sealing connection between the transition section casing and the measuring casing.

[0014] Furthermore, the outlet end of the floating casing is plugged into the inlet end of the measuring casing, an asbestos packing is provided in the gap between the overlapping portion of the floating casing and the measuring casing, and retaining rings are provided on both sides of the asbestos packing to limit the asbestos packing from escaping from the gap.

[0015] Furthermore, the air intake section includes an air intake front section and an air intake rear section, and the air intake front section, the air intake rear section and the center cone casing flow channel are continuous square-to-circular expansion sections.

[0016] Furthermore, the outlet inverted cone is a hollow structure, and a pressure equalizing hole is provided on the outlet inverted cone to connect the outlet inverted cone cavity and the air flow channel.

[0017] To achieve the above technical effects, the present invention further provides a method for designing an engine air intake device with a precooler, which is used to obtain the engine air intake device with a precooler, comprising:

[0018] Construct a three-dimensional simulation model including the air intake section, center cone casing, guide center cone, outlet reverse cone, pre-cooling casing and pre-cooler components;

[0019] Taking the structural dimensions of the air intake section, the center cone casing, the guide center cone and the precooler assembly as boundary conditions, and the incoming flow parameters and cooling medium parameters under the air intake test condition as input, the three-dimensional simulation model is analyzed using fluid simulation software to simulate the incoming flow pressure loss and airflow heat transfer coefficient under different outlet reverse cone size parameters; the outlet reverse cone size parameters include cone angle and axial length

[0020] Taking the outlet inverse cone size parameter as the independent variable and the inflow pressure loss and airflow heat transfer coefficient under the corresponding conditions as the dependent variables, the first functional relationship between the inflow pressure loss and the outlet inverse cone size parameter and the second functional relationship between the airflow heat transfer coefficient and the outlet inverse cone size parameter were constructed;

[0021] According to the design pressure loss limit value and the airflow heat transfer coefficient limit value of the engine intake device with precooler, the first functional relationship and the second functional relationship are used to analyze and obtain the parameter combination of the outlet reverse cone angle and axial length that meets the design requirements.

[0022] Compared with the existing technology, the beneficial effects of the present invention are: the present invention simulates the actual inlet flow field state of the fan-shaped afterburner through the structural design of the servo electric cylinder and the transmission mechanism, especially can realize the simulation of the fan-shaped afterburner test environment with different inlet cosine angles by continuously changing and synchronously adjusting the angle of the intake guide vane, and obtain the cosine angle distribution of the inlet airflow of the fan-shaped afterburner, so that the test environment is closer to the real working environment, which can support the efficient implementation of the performance test of the afterburner of the aircraft engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the engine air intake device with a precooler in the embodiment;

[0024] Figure 2 Schematic diagram of the tube bundle structure formed by capillaries in the embodiment;

[0025] Figure 3 Schematic diagram of the structure of the pressure equalizing hole in the embodiment;

[0026] Figure 4 Schematic diagram of the installation structure of the floating casing in the embodiment;

[0027] Among them, 1. Center cone casing; 2. Air intake section; 3. Mounting support plate; 4. Guide center cone; 5. Pre-cooling casing; 6. Pre-cooler assembly; 601. Capillary tube; 602. Inlet branch pipe; 603. Outlet branch pipe; 7. Outlet reverse cone; 8. Measuring casing; 9. Transfer section casing; 10. Floating casing; 11. Pressure equalizing hole; 12. Asbestos packing; 13. Retaining ring. DETAILED DESCRIPTION

[0028] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0029] Example

[0030] See also Figures 1-4 , an engine air intake device with a precooler, comprising:

[0031] A central cone casing 1, wherein the inlet end of the central cone casing 1 is connected to the outlet end of the air intake section 2, and a guide central cone 4 is fixed in the central cone casing 1 via a mounting support plate 3, with the cone tip of the guide central cone 4 facing the incoming flow direction;

[0032] A pre-cooling casing 5, the inlet end of which is coaxially fixedly connected to the central cone casing 1, and the diameter of the pre-cooling casing 5 decreases smoothly along the airflow direction to form a contraction flow channel;

[0033] The precooler assembly 6 is mainly composed of a plurality of capillary tubes 601, which are evenly distributed along the circumference with the central axis of the precooling casing 5 as the axis. The capillary tubes 601 are used for fluid cooling medium, and a gap for airflow is provided between adjacent capillary tubes 601. An airflow channel for airflow from the intake section 2 is formed between the precooler assembly 6 and the precooling casing 5.

[0034] The outlet anti-cone 7 is coaxially fixed to the end of the central cone away from the incoming flow direction, the large diameter starting end of the outlet anti-cone 7 is located near the outlet end of the central cone casing 1, and the conical tip of the outlet anti-cone 7 extends in the direction of airflow to a position near the outlet end of the pre-cooling casing 5.

[0035] In this embodiment, the high-temperature air captured by the air inlet duct flows through the air inlet section 2 to the center cone casing 1, and the air is guided by the guide center cone 4 into the pre-cooling casing 5; the engine air intake device of this embodiment integrates the pre-cooler and the air inlet duct into a design with a compact overall structure and low overall complexity, and can achieve efficient air intake pre-cooling and low-loss flow; on the premise of meeting the heat exchange requirements and flow resistance requirements, a capillary 601 bundle pre-cooler structure is adopted, which is lighter; in addition, by designing the pre-cooling casing 5 as a contracting flow channel, the heat exchange between the air and the internal pre-cooler assembly 6 can be enhanced; the outlet reverse cone 7 is designed at the outlet position of the center cone casing 1, which can better discharge the airflow passing through the pre-cooler assembly 6 and alleviate the problem of high inlet back pressure.

[0036] In this embodiment, the precooler assembly 6 also includes an inlet branch 602 and an outlet branch 603, with each capillary tube 601 connected between the inlet branch 602 and the outlet branch 603. Both the inlet branch 602 and the outlet branch 603 are flexible hoses capable of adaptively deforming according to the relative displacement between the central cone and the precooling casing 5, effectively alleviating structural stress concentration caused by thermal expansion, contraction, or vibration. The flexible hoses utilize a multi-layer corrugated stainless steel lining with a composite ceramic fiber braided layer, achieving axial and radial flexibility compensation while maintaining airtightness. A clamp-type quick-release connector allows for modular assembly of the capillary tubes 601 bundle, significantly improving the fatigue resistance and ease of maintenance of the precooler assembly 6.

[0037] In this embodiment, a plurality of mounting protrusions are circumferentially arranged near the outlet end of the precooling casing 5. The inlet branch 602 and outlet branch 603 corresponding to the capillary tube 601 are respectively secured to these mounting protrusions. Each capillary tube 601 is connected between the inlet branch 602 and the outlet branch 603 in a bent manner. In the assembly sequence, the precooling casing 5 is installed first, and then the inlet branch 602 and outlet branch 603 corresponding to each capillary tube 601 of the precooler assembly 6 are connected through insertion. This allows axial deformation to be compensated for by axial clearance, reducing installation difficulty. After installation, the bent portion of the capillary tube 601 is a free end, preventing damage to the capillary tube 601 due to mismatched axial thermal deformation.

[0038] During the specific installation process, the capillary 601 can be brazed vertically with the inlet branch 602 and the outlet branch 603 at high temperature to facilitate the optimization of the layout of the capillary 601 and the corresponding inlet branch 602 and outlet branch 603. This embodiment forms a precooler structure by forming a circumferentially uniformly staggered layout with the inner diameter of the precooler assembly 6 as the starting point, and connecting it to a pair of annular inlet and outlet hoses. The heat exchange medium flows from the annular inlet hose and is distributed to the inlet branch 602 of each capillary 601, flows along the capillary 601 for heat exchange, and then flows out from the annular outlet hose after being collected at each outlet branch 603. The heat exchange medium in the capillary 601 is partially cross-flow with the air outside the tube, and is generally in a countercurrent form. This arrangement not only optimizes space utilization, but also ensures that the airflow can be evenly distributed when passing through the capillary 601 bundle, ensuring that the airflow can maintain a relatively stable velocity and pressure distribution during the flow process, reducing the occurrence of turbulence and eddy currents, and further improving the heat exchange efficiency.

[0039] This embodiment also includes a measuring casing 8 and a transition section casing 9. One end of the transition section casing 9 is coaxially fixedly connected to the outlet end of the precooling casing 5, and the other end of the transition section casing 9 is coaxially fixedly connected to the measuring casing 8 via a floating casing 10. The transition section casing 9 is used to guide the airflow from the airflow channel into the measuring casing 8, and the floating casing 10 is used to achieve a movable and sealed connection between the transition section casing 9 and the measuring casing 8. Specifically, the transition section casing 9 and the measuring casing 8 are connected by a floating structure. The floating structure is composed of the floating casing 10, a clamping end cover, a retaining ring 13, and asbestos packing 12. The purpose of the floating structure is to balance the axial stress of the air intake device and compensate for the precooler inlet and outlet hoses, further avoiding the problem of thermal deformation mismatch caused by the axial direction of the air intake device.

[0040] In this embodiment, the air intake section 2 includes an air intake front section and an air intake rear section. The air intake front section, the air intake rear section and the center cone casing 1 flow channel are continuous square-to-circular expansion sections, which ensures a smooth transition of the airflow, avoids airflow turbulence caused by sudden shape changes, and reduces the resistance and energy loss of the airflow during the conversion process.

[0041] In this embodiment, the outlet inverted cone 7 is hollow to reduce weight. Furthermore, a pressure-equalizing hole 11 is provided on the outlet inverted cone 7, connecting the outlet inverted cone 7 cavity with the airflow channel. This serves to balance the pressure within the guide center cone 4 and the outlet inverted cone 7 cavity and the external flow channel, thereby improving airflow stability. The pressure-equalizing holes 11 are evenly distributed across the surface of the outlet inverted cone 7, preventing incoming hot gas from entering the cavity. This balances pressure without affecting heat exchange.

[0042] Based on the same inventive concept, this embodiment also provides a method for designing an engine air intake device with a precooler, comprising:

[0043] Step 1: Construct a three-dimensional simulation model including the air intake section 2, the central cone casing 1, the guide central cone 4, the outlet reverse cone 7, the pre-cooling casing 5, and the pre-cooler assembly 6;

[0044] Step 2: Using the structural dimensions of the air intake section 2, the central cone casing 1, the guide central cone 4, and the precooler assembly 6 as boundary conditions, and the incoming flow parameters and cooling medium parameters under the air intake duct test condition as input, the three-dimensional simulation model is analyzed using fluid simulation software to simulate the incoming flow pressure loss and airflow heat transfer coefficient under different dimensional parameters of the outlet reverse cone 7; the dimensional parameters of the outlet reverse cone 7 include the cone angle and axial length;

[0045] Step 3: Using the size parameters of the outlet inverted cone 7 as independent variables and the inflow pressure loss and the airflow heat transfer coefficient under corresponding conditions as dependent variables, construct a first functional relationship between the inflow pressure loss and the size parameters of the outlet inverted cone 7, and a second functional relationship between the airflow heat transfer coefficient and the size parameters of the outlet inverted cone 7;

[0046] Step 4: Based on the design pressure loss limit value and the airflow heat transfer coefficient limit value of the engine intake device with a precooler, the first functional relationship and the second functional relationship are used to analyze and obtain the outlet reverse cone 7 cone angle and axial length parameter combination that meets the design requirements.

[0047] In this embodiment, by establishing a three-dimensional simulation model and performing fluid simulation analysis, a correlation between the incoming flow pressure loss and the airflow heat transfer coefficient and the outlet reverse cone 7 is constructed. This correlation comprehensively considers the influence of the structural parameters of the outlet reverse cone 7 on the incoming flow pressure loss and the airflow heat transfer coefficient, so as to ensure that the optimal parameter combination of the cone angle and axial length of the outlet reverse cone 7 that meets the design requirements is obtained, thereby improving the overall performance of the engine intake device.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An engine air intake device with a precooler, characterized in that: include: A central cone casing (1), wherein the inlet end of the central cone casing (1) is connected to the outlet end of the air intake section (2), a flow guide central cone (4) is fixed in the central cone casing (1) via a mounting support plate (3), and the cone tip of the flow guide central cone (4) faces the incoming flow direction; A pre-cooling casing (5), wherein the inlet end of the pre-cooling casing (5) is coaxially fixedly connected to the central cone casing (1), and the diameter of the pre-cooling casing (5) decreases smoothly along the flow direction of the airflow to form a contraction flow channel; A precooler assembly (6), wherein the precooler assembly (6) is mainly composed of a plurality of capillaries (601), wherein the plurality of capillaries (601) are evenly distributed along the circumferential direction with the central axis of the precooling casing (5) as the axis; a fluid cooling medium is used in the capillaries (601), and a gap for air flow to pass through is provided between two adjacent capillaries (601); an air flow channel for the air inlet section (2) to flow through is formed between the precooler assembly (6) and the precooling casing (5); An outlet reverse cone (7) is coaxially fixed to the end of the central cone away from the incoming flow direction, the large diameter starting end of the outlet reverse cone (7) is located near the outlet end of the central cone casing (1), and the conical tip of the outlet reverse cone (7) extends in the direction of airflow to a position near the outlet end of the pre-cooling casing (5).

2. The engine air intake device with a precooler according to claim 1, characterized in that: The precooler assembly (6) further comprises an inlet branch (602) and an outlet branch (603), and each capillary tube (601) is connected between the inlet branch (602) and the outlet branch (603); the inlet branch (602) and the outlet branch (603) are both flexible hoses.

3. The engine air intake device with a precooler according to claim 1, characterized in that: A plurality of mounting protrusions are circumferentially arranged near the outlet end of the pre-cooling casing (5), and the inlet branch pipe (602) and the outlet branch pipe (603) corresponding to the capillary tube (601) are respectively fixed on the mounting protrusions; each capillary tube (601) is connected between the inlet branch pipe (602) and the outlet branch pipe (603) in a bent form.

4. The engine air intake device with a precooler according to claim 1, characterized in that: The invention also comprises a measuring casing (8) and a transition section casing (9), wherein one end of the transition section casing (9) is coaxially fixedly connected to the outlet end of the pre-cooling casing (5), and the other end of the transition section casing (9) is coaxially fixedly connected to the measuring casing (8) via a floating casing (10); the transition section casing (9) is used to guide the airflow of the airflow channel into the measuring casing (8), and the floating casing (10) is used to realize a movable sealing connection between the transition section casing (9) and the measuring casing (8).

5. The engine air intake device with a precooler according to claim 4, characterized in that: The outlet end of the floating casing (10) is plugged into the inlet end of the measuring casing (8), and an asbestos packing (12) is provided at the gap position between the overlapping portion of the floating casing (10) and the measuring casing (8). Retaining rings (13) are provided on both sides of the asbestos packing (12) to limit the asbestos packing (12) from escaping from the gap position.

6. The engine air intake device with a precooler according to claim 1, characterized in that: The air intake section (2) comprises an air intake front section and an air intake rear section, and the air intake front section, the air intake rear section and the flow passage of the central cone casing (1) are continuous square-to-circular expansion sections.

7. The engine air intake device with a precooler according to claim 1, characterized in that: The outlet reverse cone (7) is a hollow structure, and a pressure equalizing hole (11) is provided on the outlet reverse cone (7) for communicating with the outlet reverse cone (7) cavity and the air flow channel.

8. A method for designing an engine air intake device with a precooler, for obtaining the engine air intake device with a precooler according to any one of claims 1 to 5, characterized in that: include: Constructing a three-dimensional simulation model including an air intake section (2), a central cone casing (1), a guide central cone (4), an outlet reverse cone (7), a precooling casing (5), and a precooler assembly (6); The structural dimensions of the air intake section (2), the central cone casing (1), the guide central cone (4) and the precooler assembly (6) are used as boundary conditions, and the incoming flow parameters and cooling medium parameters under the air intake duct test working condition are used as input. The three-dimensional simulation model is analyzed using fluid simulation software to simulate the incoming flow pressure loss and airflow heat transfer coefficient under different dimensional parameters of the outlet reverse cone (7); the dimensional parameters of the outlet reverse cone (7) include the cone angle and the axial length. Taking the size parameter of the outlet inverted cone (7) as the independent variable and the incoming flow pressure loss and the airflow heat transfer coefficient under the corresponding conditions as the dependent variables, a first functional relationship between the incoming flow pressure loss and the size parameter of the outlet inverted cone (7) and a second functional relationship between the airflow heat transfer coefficient and the size parameter of the outlet inverted cone (7) are constructed; According to the design pressure loss limit value and the airflow heat transfer coefficient limit value of the engine air intake device with a precooler, the first functional relationship and the second functional relationship are used to analyze and obtain the outlet reverse cone (7) cone angle and axial length parameter combination that meets the design requirements.

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