Thermal protection system and method for improving the spreadability of a transpiration cooling air film on the outer surface of an aircraft

Abstract

The application provides a heat protection system and method for improving the spreadability of sweating air film on the outer surface of an aircraft. The heat protection system comprises an upstream sweating area, a middle suction area, a downstream sweating area and a measurement control unit. The upstream sweating area is located at the nose cone or the leading edge of the aircraft wing. The middle suction area and the downstream sweating area are connected by pipelines and arranged in sequence on the surface of the aircraft downstream of the upstream sweating area along the airflow direction during flight. The measurement control unit is used for measuring the heat flow of the sweating area and regulating the initial sweating of the upstream sweating area, the suction of the middle suction area and the re-sweating of the downstream sweating area by controlling the state of the electronic steady pressure valve, the electronic stop valve and the micro piezoelectric pump. The application improves the spreadability of the sweating air film by arranging the suction area downstream of the sweating area. The re-sweating area is arranged downstream of the suction area, and the suction area and the re-sweating area are linked by the piezoelectric pump to realize the reuse of the cooling gas.

Description

Technical Field

[0001] This invention relates to a thermal protection system and method for improving the spreadability of a sweat-generating air film on the outer surface of an aircraft, belonging to the field of aircraft heat reduction and drag reduction technology. Background Technology

[0002] For high-speed cruising aircraft, wave drag generated by the prevalent strong shock wave system accounts for two-thirds of the total cruising drag, and this proportion increases sharply with the Mach number of the incoming flow, severely affecting the aerodynamic performance of the aircraft. Furthermore, at the same speed and range, more fuel is required, leading to a significant reduction in payload. Simultaneously, the significant increase in flight speed enhances the viscosity between airflow molecules, causing a surge in heat flow to the aircraft's nose wall directly facing the incoming flow, resulting in increased wall temperature. This, in turn, damages the aircraft's sensors and drastically reduces its operational performance. These problems pose serious challenges to the practical application of high-speed aircraft. Therefore, the development of new active heat reduction and drag reduction technologies is imperative. Sweating cooling is a highly promising active heat reduction and drag reduction technology. Its heat reduction and drag reduction are mainly manifested in two aspects: first, utilizing the high specific surface area of ​​porous media to absorb heat through convection; second, the coolant forms an air film on the surface after flowing out of the porous media, achieving heat reduction and drag reduction. During missions, high-speed aircraft often engage in maneuvering (such as level flight acceleration / deceleration, dives, and climbs). Under these highly dynamic flight conditions, when the sweating film flows downstream along the aircraft surface, the flow becomes unstable, resulting in poor film spreadability and affecting the heat reduction and drag reduction effects. Summary of the Invention

[0003] The technical problem solved by the present invention is to overcome the shortcomings of the prior art and provide a thermal protection system and method for improving the spreadability of the sweating air film on the outer surface of an aircraft, thereby enhancing the sweating cooling, heat reduction and drag reduction effect, while reducing the amount of working fluid used and improving the carrying efficiency of the aircraft.

[0004] The technical solution of this invention is: on the one hand, to provide a thermal protection system that improves the spreadability of the sweating gas film on the outer surface of an aircraft, comprising: an upstream sweating zone, an intermediate suction zone, a downstream sweating zone, and a measurement and control unit; wherein:

[0005] The upstream sweating zone is located at the nose cone or leading edge of the rudder of the aircraft and is used for initial sweating to form thermal protection for the upstream area.

[0006] The intermediate suction zone and the downstream sweating zone are connected by pipelines and are arranged sequentially on the aircraft surface downstream of the upstream sweating zone along the airflow direction during flight; the intermediate suction zone performs suction to ensure stable flow of the sweating air film; the downstream sweating zone is used for re-sweating to form thermal protection for the downstream area.

[0007] The measurement and control unit measures the heat flow in the upstream sweating zone and regulates the initial sweating in the upstream sweating zone, the suction in the intermediate suction zone, and the re-sweating in the downstream sweating zone.

[0008] Preferably, the grooved area provided on the leading edge of the nose cone or rudder of the aircraft in the upstream sweating zone includes a cold air bottle, a cold air chamber, and a porous medium;

[0009] The cold air chamber is located at the bottom of the groove, the porous medium is located at the top of the groove, and the cold air bottle is connected to the cold air chamber.

[0010] Preferably, the intermediate suction zone and the downstream sweating zone have the same structure, both being grooved areas on the surface of the aircraft, including a porous medium in the upper part of the groove and a cold air cavity in the lower part.

[0011] Preferably, the optimal distance between the upstream sweating zone and the intermediate suction zone, as well as the optimal distance between the intermediate suction zone and the downstream sweating zone, are determined through numerical simulation during the design phase based on the incoming flow state and the characteristic dimensions of the application area.

[0012] Preferably, the measurement and control unit includes a data acquisition unit, a controller, a heat flux sensor, an electronic pressure regulating valve, an electronic shut-off valve, and a miniature piezoelectric pump; specifically:

[0013] The heat flow sensor is embedded in a porous medium within the upstream sweating zone;

[0014] An electronic pressure regulator is installed between the cold air cylinder and the cold air chamber in the upstream sweating zone;

[0015] An electronic shut-off valve and a miniature piezoelectric pump are installed on the pipeline between the intermediate suction zone and the downstream sweating zone.

[0016] Preferably, the number of intermediate suction zones and downstream sweating zones is determined based on the specific application.

[0017] On the other hand, a thermal protection method for improving the spreadability of perspiration film on the outer surface of an aircraft is provided, including:

[0018] During flight, the data acquisition unit acquires the measurement values ​​from the heat flux sensor in real time and sends them to the controller;

[0019] When the actual heat flow value measured by the heat flow sensor is greater than the design value, the controller switches the electronic pressure regulating valve from the closed state to the open state, so that the cooling gas enters the cooling chamber and porous medium in the upstream sweating zone from the cooling gas cylinder along the pipeline, and flows out of the aircraft surface after completing the heat exchange.

[0020] The controller switches the electronic shut-off valve from the closed state to the open state and controls the micro piezoelectric pump to work. Under the combined action of the positive pressure of the incoming gas and the negative pressure of the intermediate suction zone, the cooling gas flowing out of the aircraft surface flows downstream along the aircraft surface. When it flows to the intermediate suction zone, part of the cooling gas continues to flow downstream, while the other part enters the porous medium and cold air chamber of the intermediate suction zone under the action of the micro piezoelectric pump. Then, it reaches the cold air chamber and porous medium of the downstream sweating zone through the pipeline, and finally flows out of the aircraft surface again and continues to flow downstream, thereby improving the spreadability of the sweating gas film.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) Based on sweating cooling, this invention proposes the idea of ​​arranging a suction area downstream, which solves the problem of poor sweating cooling gas film spreadability during high-maneuver flight and can effectively improve the sweating heat reduction and drag reduction effect.

[0023] (2) The present invention arranges a re-sweating zone downstream of the suction zone, and the suction zone and the re-sweating zone are linked by a micro piezoelectric pump, realizing the reuse of cooling gas. While improving the sweating, heat reduction and drag reduction effect, it can reduce the amount of working fluid used and improve the carrying efficiency of the aircraft. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the system composition of the present invention;

[0025] Figure 2 This is a flowchart of the system operation method of the present invention. Detailed Implementation

[0026] The upstream sweating zone 1 is located at the leading edge of the aircraft's nose cone or rudder wing and is used for initial sweating to provide thermal protection to the upstream area.

[0027] The intermediate suction zone 2 and the downstream sweating zone 3 are connected by a pipe 6 and are arranged sequentially on the aircraft surface downstream of the upstream sweating zone 1 along the airflow direction during flight. The intermediate suction zone 2 is used to perform suction to ensure the flow stability of the sweating air film. The downstream sweating zone 3 is used for re-sweating to form thermal protection for the downstream area.

[0028] The measurement and control unit 4 is used to measure the heat flow in the sweating zone, and regulates the initial sweating in the upstream sweating zone, the suction in the intermediate suction zone, and the re-sweating in the downstream sweating zone by controlling the state of the electronic pressure regulating valve, the electronic shut-off valve, and the micro piezoelectric pump.

[0029] The cold air chamber 12 is located at the lower part of the groove, the porous medium 13 is located at the upper part of the groove, and the cold air bottle 11 is connected to the cold air chamber 12; the intermediate suction area 2 and the downstream sweating area 3 have the same structure, both of which are groove areas set on the surface of the aircraft, including the porous medium located at the upper part of the groove and the cold air chamber located at the lower part.

[0030] like Figure 1 As shown, the thermal protection system for improving the spreadability of the sweating film on the outer surface of an aircraft according to the present invention includes an upstream sweating zone 1, an intermediate suction zone 2, a downstream sweating zone 3, and a measurement and control unit 4; the upstream sweating zone 1, the intermediate suction zone 2, and the downstream sweating zone 3 are arranged on the aircraft surface 5; the aircraft surface 5 is particularly suitable for the nose cone or leading edge of the rudder of the aircraft; the upstream sweating zone 1 includes a cold air cylinder 11, a cold air chamber 12, and a porous medium 13; the intermediate suction zone 2 includes a porous medium 21 and a cold air chamber 22; the downstream sweating zone 3 includes a porous medium 31 and a cold air chamber 32. The intermediate suction zone 2 and the downstream sweating zone 3 are connected by a pipeline 6. The measurement and control unit 4 includes a data acquisition unit 41, a controller 42, a heat flow sensor 43, an electronic pressure regulating valve 44, an electronic shut-off valve 45, and a miniature piezoelectric pump 46. The heat flow sensor 43 is embedded in the porous medium 13 of the upstream sweating zone 1. The electronic pressure regulating valve 44 is installed between the cold air cylinder 11 and the cold air chamber 12 in the upstream sweating zone 1. The electronic shut-off valve 45 and the miniature piezoelectric pump 46 are installed on the pipeline 6 between the intermediate suction zone 2 and the downstream sweating zone 3. The number of intermediate suction zones 2 and downstream sweating zones 3 is not limited to one and can be flexibly determined according to specific usage.

[0031] like Figure 1 and Figure 2 As shown, the workflow of this invention is as follows: During flight, the data acquisition unit 41 acquires the measured values ​​of the heat flow sensor 43 in real time and transmits them to the controller 42; when the actual heat flow value measured by the heat flow sensor 43 is greater than the design value, the controller 42 switches the electronic pressure regulating valve 44 and the electronic shut-off valve 45 from the closed state to the open state, and controls the micro piezoelectric pump 46 to work; under pressure, the cooling gas enters the cooling chamber 12 and the porous medium 13 sequentially from the cooling gas cylinder 11 along the pipeline, and flows out after completing heat exchange. The cooling gas flowing out of the aircraft surface 5, under the combined action of the positive pressure of the incoming gas and the negative pressure of the intermediate suction zone 2, flows downstream along the aircraft surface 5. When it flows to the intermediate suction zone 2, part of the cooling gas continues to flow downstream, while the other part of the gas, under the action of the micro piezoelectric pump 46, enters the porous medium 21, the cold air chamber 22, the pipeline 6, the cold air chamber 32 and the porous medium 31 of the downstream sweating zone 3 in sequence, and finally flows out of the aircraft surface 5 again and continues to flow downstream.

[0032] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A thermal protection system for improving the spreadability of a sweat-generating air film on the outer surface of an aircraft, characterized in that... include: The system comprises an upstream sweating zone (1), a middle suction zone (2), a downstream sweating zone (3), and a measurement and control unit (4); wherein: The upstream sweating zone (1) is located at the nose cone or leading edge of the aircraft's rudder wing and is used for initial sweating to form thermal protection for the upstream area; The intermediate suction zone (2) and the downstream sweating zone (3) are connected by a pipe (6) and are arranged sequentially on the aircraft surface downstream of the upstream sweating zone (1) along the airflow direction during flight; the intermediate suction zone (2) performs suction to ensure stable flow of the sweating air film; the downstream sweating zone (3) is used for re-sweating to form thermal protection for the downstream area; The measurement control unit (4) measures the heat flow in the upstream sweating zone and regulates the initial sweating in the upstream sweating zone, the suction in the intermediate suction zone, and the re-sweating in the downstream sweating zone.

2. The thermal protection system for improving the spreadability of perspiration film on the outer surface of an aircraft according to claim 1, characterized in that: The upstream sweating zone (1) is a grooved area set at the leading edge of the aircraft's nose cone or rudder wing, including a cold air bottle (11), a cold air chamber (12), and a porous medium (13); The cold air chamber (12) is located at the lower part of the groove, the porous medium (13) is located at the upper part of the groove, and the cold air bottle (11) is connected to the cold air chamber (12).

3. A thermal protection system for improving the spreadability of a sweat-generating air film on the outer surface of an aircraft according to claim 2, characterized in that: The intermediate suction zone (2) and the downstream sweating zone (3) have the same structure. They are both groove areas set on the surface of the aircraft, including a porous medium in the upper part of the groove and a cold air cavity in the lower part.

4. A thermal protection system for improving the spreadability of a sweat-generating film on the outer surface of an aircraft according to claim 1, characterized in that: The optimal distance between the upstream sweating zone (1) and the intermediate suction zone (2), as well as the optimal distance between the intermediate suction zone (2) and the downstream sweating zone (3), are determined by numerical simulation based on the incoming flow state and the characteristic size of the application area during the design phase.

5. A thermal protection system for improving the spreadability of a sweat-generating air film on the outer surface of an aircraft according to claim 3, characterized in that: The measurement and control unit (4) includes a data acquisition unit (41), a controller (42), a heat flow sensor (43), an electronic pressure regulating valve (44), an electronic shut-off valve (45), and a miniature piezoelectric pump (46); specifically: The heat flow sensor (43) is embedded in the porous medium (13) of the upstream sweating zone (1); An electronic pressure regulator (44) is installed between the cold air bottle (11) and the cold air chamber (12) in the upstream sweating zone (1); An electronic shut-off valve (45) and a miniature piezoelectric pump (46) are installed on the pipeline (6) between the intermediate suction zone (2) and the downstream sweating zone (3).

6. A thermal protection system for improving the spreadability of a sweat-generating air film on the outer surface of an aircraft according to claim 1, characterized in that: The number of intermediate suction zones (2) and downstream sweating zones (3) is determined according to the specific usage.

7. A thermal protection method for improving the spreadability of a sweat-generating air film on the outer surface of an aircraft, characterized in that... include: During flight, the data acquisition unit (41) acquires the measurement values ​​of the heat flow sensor (43) in real time and sends them to the controller (42); When the actual heat flow value measured by the heat flow sensor (43) is greater than the design value, the controller (42) switches the electronic pressure regulator (44) from the closed state to the open state, so that the cooling gas enters the cooling chamber (12) and porous medium (13) of the upstream sweating zone (1) from the cooling gas cylinder (11) along the pipeline, and flows out of the aircraft surface after completing the heat exchange. The controller (42) switches the electronic shut-off valve (45) from the closed state to the open state and controls the micro piezoelectric pump (46) to work, so that the cooling gas flowing out of the aircraft surface flows downstream along the aircraft surface under the combined action of the positive pressure of the incoming gas and the negative pressure of the intermediate suction zone (2). When it flows to the intermediate suction zone (2), part of the cooling gas continues to flow downstream, and the other part of the gas enters the porous medium and cold air chamber of the intermediate suction zone (2) under the action of the micro piezoelectric pump (46). Then it reaches the cold air chamber and porous medium of the downstream sweating zone (3) through the pipeline (6), and finally flows out of the aircraft surface again and continues to flow downstream, thereby improving the spreadability of the sweating gas film.

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