An active-passive composite staggered discrete slot structure hydrocarbon fuel supersonic air film cooling system

Abstract

The present invention proposes an active-passive composite staggered discrete slot structure hydrocarbon fuel supersonic air film cooling system. The inner side of the cooling ring is fitted with the wall of the engine combustion chamber, and a composite material structure is used on the fitting surface to meet its own thermal protection requirements. The hydrocarbon fuel flows into the stagnation chamber in the cooling ring from the regenerative cooling channel and uses the accelerating nozzle to achieve critical injection, while providing regenerative cooling for the cooling ring in the process. In order to make up for the defects of the lateral diffusion effect of the supersonic air film and ensure the structural strength of the combustion chamber, a staggered discrete slot air film injection method with full circumferential coverage of the combustion chamber is proposed. This cooling system realizes efficient regeneration / film composite cooling of the scramjet combustion chamber while ensuring its own thermal protection, effectively improving the performance of the hypersonic ramjet engine without affecting the engine size as much as possible.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal protection and structural design of a hydrocarbon fuel scramjet engine combustion chamber, and in particular relates to a hydrocarbon fuel supersonic air film cooling system with an active-passive composite staggered discrete slot structure. Background Art

[0002] As the flight potential of conventional aircraft is gradually being fully developed, countries are increasingly turning their attention to the research of hypersonic aircraft, with high-Mach number ramjets (Ma>5) serving as the primary power source for these vehicles. While the development of scramjet technology has led to the entry of several models of hypersonic missiles capable of short-duration operation, research into manned hypersonic aircraft capable of extended operation over a wide range of conditions is significantly less mature. This is primarily due to the inability of single-use regenerative cooling methods to meet the cooling requirements of the engine's combustion chamber.

[0003] The regenerative / air film composite cooling solution is an advanced approach to improving the cooling capacity of cooling systems. In this solution, the low-temperature hydrocarbon fuel in the tank first flows into the cooling channel machined into the wall of the engine combustion chamber, absorbing heat and sharing the wall's heat load while increasing its own temperature. The fuel flowing out of the channel is ejected closely against the wall in the form of an air film, insulating the high-temperature mainstream and further reducing the wall's heat load. In this process, the ability to organize a hydrocarbon fuel air film within the boundary layer of the combustion chamber wall is a key component of the regenerative / air film composite cooling solution in achieving its thermal protection goals. Furthermore, the inlet parameters and injection method of the hydrocarbon fuel air film significantly influence the air film cooling effect. Therefore, the design quality of the air film cooling ring structure significantly affects the cooling capacity of the entire cooling system.

[0004] Since the hydrocarbon fuels currently widely used are all large-molecule hydrocarbon fuels, the special physical properties of these fuels result in accelerated flow in the convergent flow channel of the cooling annulus being different from that of a general convergent nozzle. In addition, the cooling annulus will be heated on one side by the combustion chamber wall, which will affect the flow in the nozzle and the reliability of the annular structure. Currently, there is no design or design process method for the relevant cooling annular structure. It is necessary to carry out a detailed design of the cooling annular structure in combination with the actual engine combustion chamber configuration to realize the design and manufacture of a hydrocarbon fuel scramjet engine combustion chamber that can operate over a wide range and for a long time. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of air film organization in the regeneration / air film composite cooling scheme, and to provide an active-passive composite staggered discrete slot structure hydrocarbon fuel supersonic air film cooling system.

[0006] The present invention is achieved through the following technical solutions. The present invention proposes an active-passive composite staggered discrete slot structure hydrocarbon fuel supersonic air film cooling system, the cooling system comprising hydrocarbon fuel 1, a fuel pump 2, a fuel tank 3, a first valve 4, a low-temperature fuel pipeline 5, a combustion chamber wall 6, a regenerative cooling channel 7, a high-temperature fuel pipeline 8, a throttle orifice plate 9, a second valve 10, and a liquid collection cavity 11;

[0007] The hydrocarbon fuel 1 is pumped out of the fuel tank 3 via the fuel pump 2, with its flow rate controlled by the first valve 4. The hydrocarbon fuel 1 then enters the regenerative cooling channel 7 machined on the combustion chamber wall 6 through the low-temperature fuel pipeline 5. During the flow, the hydrocarbon fuel 1 absorbs heat and increases in temperature. The hydrocarbon fuel 1 is then discharged from the outlet of the regenerative cooling channel 7 via the high-temperature fuel pipeline 8. The pressure in the regenerative cooling channel 7 is higher than the critical pressure of the fuel, so an adjustable throttle orifice 9 is added to the high-temperature fuel pipeline 8. After the hydrocarbon fuel 1 passes through the throttle orifice 9, the pressure decreases, and the flow before and after the throttle orifice 9 is decoupled. The hydrocarbon fuel 1 then flows through the second valve 10 and enters the liquid collection chamber 11 in the cooling ring. The hydrocarbon fuel 1 completes flow redistribution in the liquid collection chamber 11 to ensure uniform distribution of fuel flow at each air film outlet. The structure behind the liquid collection chamber 11 is a unilaterally contracting acceleration nozzle. A straight section is connected after the acceleration nozzle to stabilize the flow. A composite structure 12 of metal and non-metallic materials is added to the inner wall of the straight section.

[0008] Furthermore, the air film cooling medium uses the engine's own fuel, which is accelerated in the contraction flow channel in the cooling ring and then sprayed out in the form of an air film against the wall.

[0009] Furthermore, the outlet slots of the air film are staggered in the circumferential direction, that is, a staggered discrete slot injection method is adopted, specifically: the air film outlets are staggered in front and back at two heights, and are continuously and uninterruptedly distributed in the circumferential direction.

[0010] Furthermore, the inner side of the cooling ring is fitted to the wall surface of the engine combustion chamber.

[0011] The beneficial effects of the present invention are:

[0012] 1. An air film is injected using a staggered discrete slot structure, which can cover the circumferential surface of the engine wall, meeting the air film's coverage requirements for the wall. Compared with a two-dimensional slot structure, it has less impact on the structural strength of the engine, reducing the difficulty of engine design.

[0013] 2. The cooling ring uses un-ejected air film fuel for regenerative cooling, and the wall in contact with the engine adopts a composite structure of metal and high-temperature resistant non-metallic materials. The active and passive composite cooling method greatly reduces the thermal protection pressure of the cooling ring and realizes the compactness of the cooling ring and engine structure.

[0014] 3. The stationary chamber in the cooling ring adopts a single-side contraction acceleration profile. When the hydrocarbon fuel reaches the slot outlet, it is a critical injection with good velocity uniformity, and the controllability of the gas film is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the structural principle of the hydrocarbon fuel supersonic air film cooling system of the present invention;

[0016] Figure 2 This is a schematic structural diagram of a hydrocarbon fuel supersonic air film cooling ring according to the present invention;

[0017] Figure 3 A schematic diagram of the structure of the staggered discrete slots of the present invention;

[0018] The figures are marked as follows: 1. hydrocarbon fuel; 2. fuel pump; 3. fuel tank; 4. first valve; 5. low-temperature fuel pipeline; 6. combustion chamber wall; 7. regeneration cooling channel; 8. high-temperature fuel pipeline; 9. throttle orifice plate; 10. second valve; 11. liquid collecting chamber; 12. composite structure of metal material and non-metallic material; 13. extended wall. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] The purpose of the present invention is to propose a hydrocarbon fuel supersonic air film cooling ring and cooling system design that takes into account the structural strength of the engine combustion chamber, can efficiently organize the hydrocarbon fuel air film, and can ensure the cooling of its own structure. The air film cooling working fluid uses the engine's own fuel. The fuel is accelerated in the contraction flow channel within the cooling ring and then ejected as an air film against the wall. Taking into account the actual engine strength and the wall coverage rate after the air film is ejected, the outlet slots of the air film are circumferentially staggered. In order to prevent the heat flow from the combustion chamber wall from burning the cooling ring, a composite structure of metal and non-metallic materials is used between the cooling ring and the combustion chamber wall, ultimately solving the problem of air film organization in the regeneration / air film composite cooling scheme.

[0021] See Figure 1-Figure 3 The present invention proposes an active-passive composite staggered discrete slot structure hydrocarbon fuel supersonic air film cooling system, the cooling system comprising hydrocarbon fuel 1, a fuel pump 2, a fuel tank 3, a first valve 4, a low-temperature fuel pipeline 5, a combustion chamber wall 6, a regenerative cooling channel 7, a high-temperature fuel pipeline 8, a throttle orifice plate 9, a second valve 10 and a liquid collecting chamber 11;

[0022] The hydrocarbon fuel 1 is pumped out from the fuel tank 3 via the fuel pump 2, and its flow rate is controlled by the first valve 4. The hydrocarbon fuel 1 then enters the regenerative cooling channel 7 machined on the combustion chamber wall 6 through the low-temperature fuel pipeline 5. During the flow, it absorbs heat and heats up. The high-temperature fuel pipeline 8 is used to guide the hydrocarbon fuel 1 out of the outlet of the regenerative cooling channel 7. The pressure in the regenerative cooling channel 7 is higher than the critical pressure of the fuel. Such a pressure is too high for the cooling ring, so an adjustable throttling orifice 9 is added to the high-temperature fuel pipeline 8. After the hydrocarbon fuel 1 passes through the throttling orifice 9, the pressure decreases, and the flow before and after the throttling orifice 9 is decoupled. The fuel then flows through the controllable second valve 10 and enters the liquid collecting chamber 11 in the cooling ring. The specific structure of the cooling ring is as shown below. Figure 2 As shown, the fuel flow is redistributed in the liquid collecting chamber 11 to ensure that the fuel flow at each air film outlet is evenly distributed. The structure behind the liquid collecting chamber 11 is a unilaterally contracting acceleration nozzle, which is connected to a straight section for stable flow. Considering the actual control design, the fuel is in a critical state at the outlet. Considering that the inner side of the acceleration section and the straight section in the cooling ring are directly connected to the high-temperature mainstream in the combustion chamber, in order to improve the heat bearing capacity of the cooling ring, a composite structure 12 of metal and non-metallic materials is added to the inner wall.

[0023] The inner side of the cooling ring is bonded to the engine combustion chamber wall. The bonded surface utilizes a composite material. Hydrocarbon fuel flows from the regenerative cooling channel into the cooling ring chamber and achieves critical injection using the accelerating nozzle. Injection slots are staggered and distributed around the combustion chamber, providing full coverage. This cooling ring provides thermal protection while enabling efficient regenerative / membrane cooling of the scramjet combustion chamber, effectively improving hypersonic ramjet performance while minimizing engine size. One side of the cooling ring is in close contact with the scramjet combustion chamber wall. This configuration offers low space utilization and minimal change in overall engine size. The side of the cooling ring in close contact with the engine is heated by the engine wall, and the hydrocarbon fuel in the chamber provides regenerative cooling. To further enhance the cooling ring's thermal resistance, the bonded wall utilizes a composite structure of hot metal and non-metallic materials. The chamber within the cooling ring features a single-sided converging acceleration section. After flowing through this profile, the hydrocarbon fuel achieves critical injection conditions with excellent velocity uniformity.

[0024] In addition, the film cooling outlet is set up with a slit outlet. Although its outlet height is very small, if a continuous hole is used, it will have a greater impact on the structural strength of the engine. Therefore, the staggered discrete slot injection method is adopted. Figure 3The figure shows an independent air film injection unit, with air film outlets staggered at two heights and continuously distributed circumferentially. Furthermore, to prevent excessive interference and entrainment between the front and rear air film strips, an extended wall 13 is provided at the rear air film outlet, achieving a more uniform air film cooling effect around the combustion chamber.

[0025] After flowing out of the regenerative cooling channel, the hydrocarbon fuel, serving as the cooling medium, first enters the stagnation chamber structure within the cooling ring, where it distributes the flow rate to the various film injection ports. Because the hydrocarbon fuel's velocity is relatively low at this point, it is directed into a single-sided converging accelerator nozzle to achieve critical injection, ensuring penetration and design consistency of the fuel film once it enters the combustion chamber.

[0026] In order to make the overall structure of the cooling ring more compact and reduce the occupied volume, the inner side of the cooling ring is fitted to the wall of the engine combustion chamber. After adopting this structure, since the combustion chamber side is in direct contact with the high-temperature mainstream, the inner material of the cooling ring will be heated by the combustion chamber wall. On the other hand, since the hydrocarbon fuel flowing in the acceleration channel absorbs heat from the regeneration cooling channel and its temperature rises, it will also heat the cooling ring wall. Therefore, requirements are put forward for the cooling protection of the cooling ring itself. Based on this, a passive thermal protection material composed of a metal and non-metal composite is arranged between the inner surface and the combustion chamber wall. The above structure forms an active and passive composite thermal protection solution that meets the thermal protection requirements of the cooling ring itself.

[0027] According to the structure of the acceleration flow channel outlet in the cooling ring, the hydrocarbon fuel gas film is injected by means of a narrow slit injection. The two-dimensional slot process has the advantages of good gas film coverage and little interference with mainstream penetration. However, the two-dimensional slot process has continuous openings, which will affect the structural strength of the engine. Considering that the lateral diffusion effect of the discrete gas film in the high Mach number combustion chamber is weak, a staggered discrete slot gas film injection method with full circumferential coverage of the combustion chamber is adopted. By organizing the gas film cooling through staggered discrete slots, the structural strength of the combustion chamber can be guaranteed while achieving the full coverage requirement of the gas film. By organizing the gas film cooling through staggered discrete slots, the fuel gas film can be guaranteed to fully cover the combustion chamber wall surface. Compared with the two-dimensional slot process, its impact on the structural strength of the engine is smaller.

Claims

1. An active-passive composite staggered discrete slot structure hydrocarbon fuel supersonic air film cooling system, characterized by: The cooling system comprises hydrocarbon fuel (1), a fuel pump (2), a fuel tank (3), a first valve (4), a low-temperature fuel pipeline (5), a combustion chamber wall (6), a regenerative cooling channel (7), a high-temperature fuel pipeline (8), a throttle orifice plate (9), a second valve (10) and a liquid collecting chamber (11); The hydrocarbon fuel (1) is pumped out from the fuel tank (3) via the fuel pump (2), and its flow rate is controlled by the first valve (4). The hydrocarbon fuel (1) then enters the regenerative cooling channel (7) machined on the combustion chamber wall (6) through the low-temperature fuel pipeline (5). During the flow, the hydrocarbon fuel (1) absorbs heat and increases in temperature. The hydrocarbon fuel (1) is then led out from the outlet of the regenerative cooling channel (7) by the high-temperature fuel pipeline (8). The pressure in the regenerative cooling channel (7) is higher than the critical pressure of the fuel, so an adjustable throttling orifice plate (9) is added to the high-temperature fuel pipeline (8). After the fuel (1) passes through the throttle orifice (9), the pressure is reduced, and at the same time, the flows before and after the throttle orifice (9) are decoupled. After that, the hydrocarbon fuel (1) flows through the second valve (10) and enters the liquid collecting cavity (11) in the cooling ring. The hydrocarbon fuel (1) completes the flow redistribution in the liquid collecting cavity (11), ensuring that the fuel flow at each air film outlet is evenly distributed. The structure behind the liquid collecting cavity (11) is a unilaterally contracted accelerating nozzle. A straight section is connected after the accelerating nozzle to stabilize the flow. A composite structure (12) of metal material and non-metal material is added to the inner wall surface of the straight section. The film cooling medium uses the engine's own fuel, which is accelerated in the contraction flow channel inside the cooling ring and then sprayed out in the form of a film against the wall; The outlet slots of the air film are staggered in the circumferential direction, that is, a staggered discrete slot injection method is adopted. Specifically, the air film outlets are staggered at two heights in the front and back, and are continuously and uninterruptedly distributed in the circumferential direction.

2. The cooling system according to claim 1, characterized in that Fit the inner side of the cooling ring to the wall of the engine combustion chamber.

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