阅读说明：本技术 一种应用于可往返式高超声速飞行器头锥表面的发散和气膜双冷却系统 (Divergent and air film double-cooling system applied to surface of reciprocating hypersonic aircraft nose cone ) 是由 李育隆 周滢 王领华 余群 于 2020-06-22 设计创作，主要内容包括：本发明提供了一种应用于可往返式高超声速飞行器头锥表面的发散与气膜双冷却系统。该发明主要包括高超声速飞行器头锥表面、发散冷却系统、气膜冷却系统,所述高超声速飞行器头锥表面分为两个区域,包含驻点的驻点区和不包含驻点的非驻点区,所述头锥表面驻点区采用发散冷却,冷却剂为液态水,所述头锥表面非驻点区采用气膜冷却,冷却剂为氮气,所述发散冷却系统与所述气膜冷却系统独立工作。本发明不仅能同时满足驻点区与非驻点区的冷却需求,驻点区冷却效率不低于90％,非驻点区冷却效率不低于60％,还能有效的降低飞行器所需要携带的冷却剂的重量。(The invention provides a divergent and air film double-cooling system applied to the surface of a nose cone of a reciprocating hypersonic aircraft. The high-supersonic aircraft nose cone surface cooling system mainly comprises a high-supersonic aircraft nose cone surface, a divergent cooling system and an air film cooling system, wherein the high-supersonic aircraft nose cone surface is divided into two areas, namely a stagnation point area containing stagnation points and a non-stagnation point area not containing stagnation points, divergent cooling is adopted in the stagnation point area on the nose cone surface, a coolant is liquid water, the non-stagnation point area on the nose cone surface is cooled by an air film, the coolant is nitrogen, and the divergent cooling system and the air film cooling system work independently. The invention not only can meet the cooling requirements of the stagnation area and the non-stagnation area at the same time, the cooling efficiency of the stagnation area is not lower than 90%, and the cooling efficiency of the non-stagnation area is not lower than 60%, but also can effectively reduce the weight of the coolant carried by the aircraft.)

1. The invention provides a divergent and air film double-cooling system applied to the surface of a reciprocating hypersonic aircraft nose cone, which is characterized by comprising a reciprocating hypersonic aircraft nose cone (17), a divergent cooling system and an air film cooling system;

the divergent cooling system comprises a water storage tank (1), a cooling water conveying pipeline, a cold liquid cavity (5), a porous wall surface (6) and a corresponding accessory system;

the air film cooling system comprises a liquid nitrogen tank (7), a gasification device (11) and an accelerating device (1)³) The device comprises a liquid nitrogen conveying pipeline, a cold air cavity (15), an air film hole array (16) and a corresponding accessory system;

the cooling water conveying pipeline comprises pumps (²) A first flow meter (3) and a corresponding conduit;

the cooling water conveying pipeline also comprises a first pressure sensor (4) arranged behind the first flowmeter (3);

the liquid nitrogen tank (7) is a self-pressurization liquid nitrogen tank;

the liquid nitrogen conveying pipeline comprises a valve (8), a gasification device (11), an acceleration device (13), a second flowmeter (14) and corresponding pipelines which are connected in sequence;

the liquid nitrogen conveying pipeline also comprises a second pressure sensor (10) and a first temperature sensor (9) which are arranged between the valve and the gasification device;

the liquid nitrogen conveying pipeline also comprises a third pressure sensor (12) arranged between the gasification device and the acceleration device;

the hypersonic aircraft nose cone (17) is divided into two areas on the surface, wherein the two areas comprise a stagnation point area (18) containing stagnation points and a non-stagnation point area (19) containing no stagnation points; the porous wall surface (6) is arranged in the stationary point area (18) of the surface of the nose cone and is connected with the cold liquid cavity (5) arranged inside the stationary point area of the nose cone; the air film hole array (16) is arranged on the non-stationary point area (19) on the surface of the nose cone and is connected with the cold air cavity (15) arranged in the non-stationary point area of the nose cone;

an included angle between the boundary line of the stationary point area on the surface of the nose cone and the central axis (20) of the aircraft nose cone is 25 degrees;

in the divergent and air film double-cooling system, divergent cooling is adopted in the stationary point area (18) on the surface of the nose cone, liquid water is used as a coolant, air film cooling is adopted in the non-stationary point area (19) on the surface of the nose cone, and nitrogen is used as the coolant; the divergent cooling system and the film cooling system operate independently.

2. A method of achieving divergent cooling of a stagnation area of a surface of said nose cone using the divergent cooling system of claim 1, characterized by the steps of:

1) after sufficient liquid cooling water is stored in the water storage tank (1), starting the pump (2) to pump the cooling water, and enabling the cooling water to reach the cold liquid cavity (5) through the conveying pipeline;

2) and the cooling water stored in the cold liquid cavity (5) is discharged after being subjected to pressure reduction vaporization of the porous wall surface (6), a protective gas film is formed in the stationary point area (18) on the surface of the nose cone, and the cooling water is vaporized to absorb heat so as to cool the stationary point area (18) on the surface of the nose cone.

3. The method of transpiration cooling of claim 2, further comprising:

when the pressure signal returned by the first pressure sensor (4) is too low, namely the pressure of the cooling water entering the cold liquid cavity (5) is insufficient, the power of the pump (2) is increased, and the pressure of the cooling water entering the cold liquid cavity (5) is ensured to be high enough.

4. A method for achieving divergent cooling of a non-stagnation area of a surface of a nose cone by using the film cooling system of claim 1, comprising the steps of:

1) after the liquid nitrogen tank (7) is ensured to store sufficient high-pressure liquid nitrogen, the valve (8) is opened, and the liquid nitrogen is changed into gas through the gasification device (11);

2) nitrogen enters a cold air cavity (15) through acceleration of an accelerating device (13), the nitrogen stored in the cold air cavity is discharged through an air film hole array (16), and a protective air film is formed on a non-stagnation area on the surface of the nose cone.

5. The method of film cooling of claim 4, further comprising:

when the pressure signal returned by the second pressure sensor (10) is too low, namely the pressure of the gasified nitrogen is insufficient, the opening degree of the valve (2) is increased to ensure that the pressure of the gasified nitrogen is high enough; when the temperature signal in the range of the first temperature sensor (9) is too high, namely the temperature of the gasified nitrogen is too high, the power of the gasification device (11) is increased to ensure that the temperature of the gasified nitrogen is low enough; when the pressure signal returned by the third pressure sensor (12) is too low, namely the nitrogen pressure after acceleration is insufficient, the power of the acceleration device is increased, and the nitrogen pressure accelerated into the cold air cavity (15) is ensured to be high enough.

6. The dual divergent and film cooling system as set forth in claim 1 wherein the first film hole of said array of film holes near the stagnation area has an angle of 5 ° to 10 ° with the central axis of the aircraft nose cone.

7. The transpiration cooling system of claim 1, wherein the porous wall has a porosity of between 0.5 and 0.9 and an average pore size of between 40 and 60 μm.

8. The film cooling system of claim 1, wherein the film holes of the array of film holes are circular in shape, the diameter of the film holes is 2mm, and the outflow angle of the film holes, i.e., the angle between the centerline of the film holes and the tangent plane of the ground wall, is 90 °.

9. The film cooling system of claim 1, wherein the array of film holes is arranged as follows: the number of the air film holes in each row is 10-100, 10 rows are arranged in total, the closer the position is to the downstream, the more the number of the air film holes in each row is, and therefore the distance between two adjacent air film holes in the same row is ensured not to be too large; in the axial direction, the axial intervals of the air film holes in adjacent rows are the same and are arranged in a staggered mode.

Technical Field

The invention belongs to the field of thermal protection of aircrafts, and particularly relates to a divergent and air film double-cooling system for a hypersonic aircraft.

Background

Since the 20 th century, aerospace engineering has been rapidly developed, the flight speeds and heights of various aircrafts are continuously challenging the limits of human science and technology, but the reciprocatable hypersonic aircrafts with the speed between mach 5 and mach 10 are still blank at present and are also the key direction of the development of the aircrafts in the future, and all aerospace countries are researched at present, the reciprocatable hypersonic aircrafts can generate pneumatic heating effect when flying in the atmospheric space, the gas close to the surface of the aircrafts is greatly heated due to severe friction, so that the surface structure of the aircrafts is heated, the temperature of the surfaces of the aircrafts, especially the parts such as a nose cone, is greatly increased, the existing materials can not bear the high temperature, proper thermal protection measures must be adopted, the traditional ablation thermal protection cannot be used repeatedly, the spraying is required to be carried out again each time the hypersonic flight vehicle flies, the cost is high, the requirements on the flying speed, the reusability and the reliability of the reciprocating hypersonic flight vehicle are higher, and the maintenance cost is lower, so that the research on a more efficient and more reliable thermal protection mode is necessary.

The active thermal protection can work for a long time under the condition of not changing the aerodynamic shape of the aircraft, can be repeatedly used, has higher cooling efficiency, and is an effective means for replacing passive thermal protection such as ablation and the like in the future. The most common active thermal protection technology comprises divergent cooling and air film cooling, wherein liquid is usually used as a coolant in the divergent cooling, the liquid is heated and vaporized in a porous wall surface, a large amount of heat can be taken away due to latent heat of vaporization in the process, the vaporized coolant is discharged through the porous wall surface, a layer of protective air film is formed on the cooled surface, and the layer of protective air film can effectively reduce heat exchange between the wall surface and main stream gas. The film cooling uses gas as coolant, the gas is discharged through a plurality of small hole structures (also called cooling holes or film holes) on the wall surface of the aircraft, and a protective film is formed on the cooled surface.

It can be seen that the cooling process of transpiration cooling consists of two parts: internal heat transfer: the coolant is vaporized to take away heat, and the outside is insulated: the gas film reduces the heat transfer of wall and mainstream gas, and the cooling process of gas film cooling only includes the latter, therefore the cooling capacity of divergent cooling is stronger, to the stagnation district of nose awl, and heat flow density is very big, and the better thermal protection demand that satisfies of divergent cooling ability.

Transpiration cooling, while having higher cooling capacity than film cooling, requires more coolant to be carried, and weight reduction is also important for aircraft, so film cooling can be used in non-stagnation areas where the heat flux density is relatively low.

The dual-cooling system with the divergent air film can meet the thermal protection requirement on the surface of the nose cone of the reciprocating hypersonic aircraft, and can effectively reduce the weight of the coolant to be carried.

The current research on film cooling and diffusion cooling is mostly focused on the premise of low-speed mainstream application, the characteristic research on film cooling and diffusion cooling under the hypersonic speed mainstream condition is less, and a double-cooling active thermal protection system combining diffusion cooling and film cooling and the research on the performance of the double-cooling active thermal protection system are absent.

Disclosure of Invention

The invention aims to provide a divergent and air film double-cooling system applied to the surface of a nose cone of a reciprocating hypersonic aircraft.

The purpose of the invention is realized by the following technical scheme:

the invention provides a divergent and air film double-cooling system applied to the surface of a reciprocating hypersonic aircraft nose cone, which is characterized by comprising a reciprocating hypersonic aircraft nose cone (17), a divergent cooling system and an air film cooling system;

the divergent cooling system comprises a water storage tank (1), a cooling water conveying pipeline, a cold liquid cavity (5), a porous wall surface (6) and a corresponding accessory system;

the air film cooling system comprises a liquid nitrogen tank (7), a gasification device (11), an acceleration device (13), a liquid nitrogen conveying pipeline, a cold air cavity (15), an air film hole array (16) and corresponding accessory systems;

the cooling water conveying pipeline comprises a pump (2), a first flowmeter (3) and corresponding pipelines which are connected in sequence;

the cooling water conveying pipeline also comprises a first pressure sensor (4) arranged behind the first flowmeter (3);

the liquid nitrogen tank (7) is a self-pressurization liquid nitrogen tank;

the liquid nitrogen conveying pipeline comprises a valve (8), a gasification device (11), an acceleration device (13), a second flowmeter (14) and corresponding pipelines which are connected in sequence;

the liquid nitrogen conveying pipeline also comprises a second pressure sensor (10) and a first temperature sensor (9) which are arranged between the valve and the gasification device;

the liquid nitrogen conveying pipeline also comprises a third pressure sensor (12) arranged between the gasification device and the acceleration device;

the hypersonic aircraft nose cone (17) is divided into two areas on the surface, wherein the two areas comprise a stagnation point area (18) containing stagnation points and a non-stagnation point area (19) containing no stagnation points; the porous wall surface (6) is arranged in the stationary point area (18) of the surface of the nose cone and is connected with the cold liquid cavity (5) arranged inside the stationary point area of the nose cone; the air film hole array (16) is arranged on the non-stationary point area (19) on the surface of the nose cone and is connected with the cold air cavity (15) arranged in the non-stationary point area of the nose cone;

an included angle between the boundary line of the stationary point area on the surface of the nose cone and the central axis (20) of the aircraft nose cone is 25 degrees;

in the divergent and air film double-cooling system, divergent cooling is adopted in the stationary point area (18) on the surface of the nose cone, liquid water is used as a coolant, air film cooling is adopted in the non-stationary point area (19) on the surface of the nose cone, and nitrogen is used as the coolant; the divergent cooling system and the film cooling system operate independently.

The divergent cooling system realizes the divergent cooling method for the stationary point area of the conical surface, and comprises the following steps:

1) after sufficient liquid cooling water is stored in the water storage tank (1), starting the pump (2) to pump the cooling water, and enabling the cooling water to reach the cold liquid cavity (5) through the conveying pipeline;

2) and the cooling water stored in the cold liquid cavity (5) is discharged after being subjected to pressure reduction vaporization of the porous wall surface (6), a protective gas film is formed in the stationary point area (18) on the surface of the nose cone, and the cooling water is vaporized to absorb heat so as to cool the stationary point area (18) on the surface of the nose cone.

When the pressure signal returned by the first pressure sensor (4) is too low, namely the pressure of the cooling water entering the cold liquid cavity (5) is insufficient, the power of the pump (2) is increased, and the pressure of the cooling water entering the cold liquid cavity (5) is ensured to be high enough.

The method for realizing the divergent cooling of the non-stagnation area on the surface of the nose cone by the air film cooling system comprises the following steps:

1) after the liquid nitrogen tank (7) is ensured to store sufficient high-pressure liquid nitrogen, the valve (8) is opened, and the liquid nitrogen is changed into gas through the gasification device (11);

2) nitrogen enters a cold air cavity (15) through acceleration of an accelerating device (13), the nitrogen stored in the cold air cavity is discharged through an air film hole array (16), and a protective air film is formed on a non-stagnation area on the surface of the nose cone.

When the pressure signal returned by the second pressure sensor (10) is too low, namely the pressure of the gasified nitrogen is insufficient, the opening degree of the valve (2) is increased to ensure that the pressure of the gasified nitrogen is high enough; when the temperature signal in the range of the first temperature sensor (9) is too high, namely the temperature of the gasified nitrogen is too high, the power of the gasification device (11) is increased to ensure that the temperature of the gasified nitrogen is low enough; when the pressure signal returned by the third pressure sensor (12) is too low, namely the nitrogen pressure after acceleration is insufficient, the power of the acceleration device is increased, and the nitrogen pressure accelerated into the cold air cavity (15) is ensured to be high enough.

The included angle between the central axis of the first air film hole of the air film hole array close to the stagnation point area and the central axis of the aircraft nose cone is 5-10 degrees.

Wherein the porosity of the porous wall surface is between 0.5 and 0.9, and the average pore diameter is between 40 and 60 μm.

The shape of the air film holes in the air film hole array is circular, the diameter of the air film holes is 2mm, and the outflow angle of the air film holes, namely the included angle between the center line of the air film holes and the tangent plane of the local wall surface, is 90 degrees.

Wherein the gas film hole array is arranged in the following form: the number of the air film holes in each row is 10-100, 10 rows are arranged in total, the closer the position is to the downstream, the more the number of the air film holes in each row is, and therefore the distance between two adjacent air film holes in the same row is ensured not to be too large; in the axial direction, the axial intervals of the air film holes in adjacent rows are the same and are arranged in a staggered mode.

The invention adopts divergent cooling in the stagnation area with high heat flux density on the surface of the head cone of the reciprocating hypersonic aircraft, water is heated in a porous wall surface from liquid state and then is vaporized, thereby taking away a large amount of latent heat of vaporization, and being capable of fully meeting the cooling requirement of the stagnation area.

Drawings

FIG. 1 is a schematic view of a dual emanation and film cooling system for a reciprocatable hypersonic aircraft according to the invention;

FIG. 2 is a schematic illustration of a stagnation area and a non-stagnation area;

FIG. 3 is a schematic view of the arrangement of the gas film holes.

Detailed Description

The present invention will be described in further detail with reference to the attached drawings, which are only illustrative and not intended to limit the scope of the present invention in any way.

Referring to fig. 1, fig. 1 is a schematic diagram of a dual transpiration and film cooling system for a shuttleable hypersonic aircraft in accordance with the present invention. The high-speed hypersonic aircraft comprises a reciprocating hypersonic aircraft nose cone, a divergent cooling system and an air film cooling system, wherein the divergent cooling system and the air film cooling system work independently.

Referring to fig. 1, the divergent cooling system comprises a water storage tank (1), a cooling water delivery pipeline, a cold liquid cavity (5), a porous wall surface (6) and a corresponding accessory system.

Referring to fig. 1, the air film cooling system comprises a liquid nitrogen tank (7), a gasification device (11), an acceleration device (13), a liquid nitrogen conveying pipeline, a cold air cavity (15), an air film hole array (16) and a corresponding accessory system.

Referring to fig. 1, the cooling water delivery pipeline includes a pump (2), a first flow meter (3) and corresponding pipes connected in sequence;

referring to fig. 1, the cooling water delivery pipeline further includes a first pressure sensor (4) disposed behind the first flowmeter (3).

Referring to fig. 1, the liquid nitrogen delivery pipeline comprises a valve (8), a gasification device (11), an acceleration device (13), a second flowmeter (14) and corresponding pipelines which are connected in sequence.

Referring to fig. 1, the liquid nitrogen delivery pipeline further includes a second pressure sensor (10) and a first temperature sensor (9) disposed between the valve and the gasification device.

Referring to fig. 1, the liquid nitrogen conveying pipeline further comprises a third pressure sensor (12) arranged between the gasification device and the acceleration device.

Referring to fig. 2, the surface of the nose cone (17) of the reciprocatable hypersonic aircraft is divided into two regions: a stagnation area (18) containing stagnation points and a non-stagnation area (19) containing no stagnation points; the porous wall surface (6) is arranged in the stationary point area (18) of the surface of the nose cone and is connected with the cold liquid cavity (5) arranged inside the stationary point area of the nose cone; the air film hole array (16) is arranged on the non-stationary point area (19) on the surface of the nose cone and is connected with the cold air cavity (15) arranged in the non-stationary point area of the nose cone;

in a particular embodiment, the boundary line of the nose cone surface stagnation region makes an angle of 25 ° with the central axis of the aircraft nose cone (fig. 2).

The steps of the divergent cooling system for realizing the thermal protection of the stationary point area on the surface of the nose cone are as follows:

1) after sufficient liquid cooling water is stored in the water storage tank, starting a pump to pump the cooling water, and enabling the cooling water to reach the cold liquid cavity through a conveying pipeline;

2) and the cooling water stored in the cold liquid cavity is discharged after being subjected to pressure reduction vaporization on the porous wall surface, a protective gas film is formed in the stationary point area on the surface of the nose cone, and the cooling water is vaporized to absorb heat to cool the stationary point area on the surface of the nose cone.

When the pressure signal returned by the first pressure sensor is too low, namely the pressure of the cooling water entering the cold liquid cavity is insufficient, the power of the pump is increased, and the pressure of the cooling water entering the cold liquid cavity is ensured to be high enough.

The method for realizing the thermal protection of the non-stagnation area on the surface of the head cone by air film cooling comprises the following steps:

1) after the liquid nitrogen tank is ensured to store sufficient high-pressure liquid nitrogen, the valve is opened, and the liquid nitrogen is changed into gas through the gasification device;

2) the nitrogen gas enters the cold air cavity after being accelerated by the accelerating device, the nitrogen gas stored in the cold air cavity is discharged through the gas film hole array, and a protective gas film is formed on the non-stagnation area on the surface of the nose cone.

When the pressure signal returned by the second pressure sensor is too low, namely the pressure of the gasified nitrogen is insufficient, the opening degree of the valve is increased to ensure that the pressure of the gasified nitrogen is high enough; when the temperature signal in the range of the first temperature sensor is too high, namely the temperature of the gasified nitrogen is too high, the power of the gasification device is increased to ensure that the temperature of the gasified nitrogen is low enough; when the pressure signal returned by the third pressure sensor is too low, namely the pressure of the accelerated nitrogen is insufficient, the power of the accelerating device is increased, and the nitrogen accelerated into the cold air cavity is ensured to be high enough.

In a specific embodiment, an included angle between a central axis of a first film hole of the film hole array close to the stagnation point area and a central axis of the aircraft nose cone is 5-10 °.

In a specific embodiment, the porosity of the porous walls is between 0.5 and 0.9 and the average pore size is between 40 μm and 60 μm.

In a specific embodiment, the shape of the film holes in the film hole array is circular, the diameter of the film holes is 2mm, and the outflow angle of the film holes, namely the included angle between the center line of the film holes and the tangent plane of the local wall surface, is 90 degrees.

In a specific embodiment, the array of gas film holes is arranged as follows: the number of the air film holes in each row is 10-100, 10 rows are arranged in total, the closer the position is to the downstream, the more the number of the air film holes in each row is, and therefore the distance between two adjacent air film holes in the same row is ensured not to be too large; in the axial direction, the air film holes of adjacent rows are arranged in a staggered mode at the same axial interval (figure 3).