Combustion chamber of scramjet engine

Abstract

The invention relates to a combustion chamber of a scramjet engine, which adopts kerosene as a cooling medium to realize phase change sweating cooling of the combustion chamber (7). The kerosene comes from a propellant of a scramjet engine and is stored in the hypersonic aircraft; a supporting plate (10) is arranged in the combustion chamber (7), a fixed wall surface (1) and a porous wall plate (2) are arranged on the supporting plate (10), the porous wall plate (2) is embedded and fixed in the fixed wall surface (1), and an increasing bag cavity (4) is formed in the inner side of the porous wall plate (2); according to the combustion chamber, phase change sweating cooling of the combustion chamber is achieved, meanwhile, the temperature of kerosene serving as fuel is increased, and the afterburning effect is achieved.

Description

Technical Field

[0001] The invention relates to a combustion chamber of a scramjet engine and belongs to the field of material thermal protection. Background Art

[0002] The heat insulation problem of the shell and engine combustion chamber of hypersonic aircraft is an important problem to improve the high-speed flight and maneuverability of hypersonic aircraft. Due to the extremely high flight speed, the hypersonic aircraft itself is severely affected by the aerodynamic thermal effect, and as the efficient propulsion system of the aircraft, the scramjet engine is also severely affected by the thermal effect.

[0003] In a scramjet engine, high-temperature air flows at supersonic speed, and the engine's body wall has a high aerodynamic heat flux density. In order to improve combustion efficiency, complex structures such as injection support plates need to be installed in the combustion chamber to inject fuel directly into the core area of ​​the supersonic mainstream. However, since the injection support plate is directly located in a high-temperature and high-speed environment, it is subject to huge thermal loads during operation, and existing materials are difficult to meet the working requirements.

[0004] In the prior art, regenerative cooling is often used as a thermal protection method. However, this method works better at lower Mach numbers. However, when the Mach number increases, its thermal protection effect is significantly reduced and cannot meet the working requirements. Therefore, it limits the development of hypersonic aircraft.

[0005] In the prior art, phase change active sweating cooling is also used for scramjet cooling in hypersonic environments. This cooling method allows the cooling liquid to flow out from the porous wall surface and undergo intense convection, so that the cooling liquid undergoes large-area heat exchange in the tortuous micro-pipes inside the wall surface, thereby efficiently removing heat. Compared with the above-mentioned regenerative cooling method, or the membrane cooling method in the prior art, the phase change active sweating cooling has a higher cooling efficiency, especially for thermal protection of extremely high temperature walls. However, during the phase change active sweating cooling process, the air film formed by the cooling liquid on the wall surface reduces the heat exchange efficiency. In addition, the materials of the sweating wall surface mainly include sintered porous materials, ceramic-based composite materials, self-sweating materials, etc., and the sweating liquid medium is mostly a non-fuel medium, which relies on self-extraction and adaptive methods to transfer the cooling medium, and the cooling efficiency is not high.

[0006] Based on the above, if a combination of wall fuel cooling and fuel injection is used for cooling and reburning, the active heat protection capability inside the ramjet engine will be improved at the same time, and kerosene should be considered as the liquid medium. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] In view of the deficiencies of the above-mentioned prior art, the present invention proposes a combustion chamber of a scramjet engine, which adopts kerosene as a cooling medium to achieve phase change sweating cooling of the combustion chamber, and the kerosene comes from the propellant of the scramjet engine; at the same time, the temperature of the kerosene is increased after achieving the above-mentioned phase change sweating cooling, and when it is used as a propellant, the preheated kerosene has a reburning effect.

[0009] (II) Technical solution

[0010] A combustion chamber of a scramjet engine, which uses kerosene as a cooling medium to achieve phase change sweating cooling of the combustion chamber; the kerosene comes from the propellant of the scramjet engine and is stored in a hypersonic aircraft; the combustion chamber is provided with a support plate, the support plate is provided with a fixed wall surface and a porous wall plate, the porous wall plate is embedded and fixed in the fixed wall surface, an increased sac cavity is arranged on the inner side of the porous wall plate, and the pressurized sac cavity can drive the cooling medium to pass through the fine flow channel in the porous wall plate, and then vaporize to the boundary layer around the fixed wall surface to form a protective air film, and the heat flux density transferred from the high-temperature mainstream to the fixed wall surface is reduced by the protective air film, so as to achieve the purpose of cooling; in this process, the cooling medium takes away the heat of the fixed wall surface, and the heated cooling medium circulates back to the propellant compartment of the scramjet engine to preheat the propellant, thereby achieving the purpose of post-combustion of the scramjet engine.

[0011] Furthermore, in the scramjet engine, the airflow passes through the air inlet, the isolation section, the combustion chamber, and the tail nozzle in sequence, and the above-mentioned phase change sweating cooling is completed in the isolation section; in the isolation section, the airflow and the cooling medium form a mixture, and the mixture forms a pre-combustion shock wave train. After passing through the pre-combustion shock wave train, the movement speed of the mixture decreases, the temperature and pressure increase, and the cooling medium is heated to achieve the purpose of preheating; at the same time, after the cooling medium stays in the isolation section for an increased time, the mixing degree of the cooling medium and oxygen is enhanced, thereby increasing the turbulent flame propagation speed.

[0012] Furthermore, the support plate has a support plate frame, which has hollow portions at the front edge and main body of the support plate for embedding corresponding porous wall panels; a pressurized cavity is arranged between the inner and outer wall surfaces of the support plate, and the additional cavity is arranged in a ring around the front edge and main body of the support plate and is internally connected.

[0013] Furthermore, the boost bladder cavity has a diameter of 2 mm, and the cooling medium is transported from the fuel tank to the boost bladder cavity through the boost pump, and the sweating rate of the cooling medium is adjusted by the oxygen pump, thereby adjusting the sweating cooling efficiency and the afterburning efficiency of the combustion chamber.

[0014] Furthermore, the support plate frame is made of high-temperature titanium alloy, and the aperture of the micro-channel in the porous wall plate is between 10-100 microns.

[0015] Furthermore, the porous wall panel is formed by metal powder injection molding. First, stainless steel 1Cr18Ni9Ti particles are mixed with an organic binder and plasticized by high-temperature heating. Then, the organic binder is volatilized by high-temperature sintering, and finally the panel is formed.

[0016] (III) Beneficial effects

[0017] The combustion chamber of a scramjet engine of the present invention innovatively proposes to use kerosene, a fuel for scramjet engines, as the cooling medium of the combustion chamber. On the one hand, the kerosene phase change is used for sweating cooling. While achieving this cooling, the heated kerosene returns to the fuel tank, the overall temperature of the fuel is increased, and the effect of supplementary combustion is achieved. At the same time, according to this scheme, the corresponding structure of the support plate is also innovatively designed. This patented technology has been applied to the demonstration of a certain scramjet model scheme, and the corresponding simulation experiments have verified the rationality and feasibility of the method of the technical scheme, providing technical support for the development of subsequent models. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of kerosene phase change sweat cooling in the combustion chamber of a scramjet engine

[0019] Figure 2 Schematic diagram of the sweat cooling and afterburning process of a scramjet combustion chamber

[0020] Figure 3 Schematic diagram of a support plate in the combustion chamber of a scramjet engine DETAILED DESCRIPTION

[0021] See also Figure 1 A combustion chamber 7 of a scramjet engine, which uses kerosene as a cooling medium to achieve phase change sweating cooling of the combustion chamber 7; the kerosene comes from the propellant of the scramjet engine and is stored in a hypersonic aircraft; a support plate 10 is provided in the combustion chamber 7, and a fixed wall surface 1 and a porous wall plate 2 are provided on the support plate 10, the porous wall plate 2 is embedded and fixed in the fixed wall surface 1, and an increased capsule 4 is arranged on the inner side of the porous wall plate 2, and the pressurized capsule 4 can drive the cooling medium to pass through the fine flow channel in the porous wall plate 2, and then vaporize into the boundary layer 3 on the periphery of the fixed wall surface 1 to form a protective gas film 9, and the heat flux density of the high-temperature mainstream transferred to the fixed wall surface 1 is reduced by the protective gas film 9, so as to achieve the purpose of cooling; in this process, the cooling medium takes away the heat of the fixed wall surface 1, and the heated cooling medium circulates back to the propellant compartment of the scramjet engine to preheat the propellant, thereby achieving the purpose of post-combustion of the scramjet engine.

[0022] See also Figure 2In the scramjet engine, the airflow passes through the air inlet 5, the isolation section 6, the combustion chamber 7, and the tail nozzle 8 in sequence, and the above-mentioned phase change sweating cooling is completed in the isolation section 6; in the isolation section 6, the airflow and the cooling medium form a mixture, and the mixture forms a pre-combustion shock wave train. After passing through the pre-combustion shock wave train, the movement speed of the mixture decreases, the temperature and pressure increase, and the cooling medium is heated to achieve the purpose of preheating; at the same time, after the cooling medium stays in the isolation section 6 for a longer time, the mixing degree of the cooling medium and oxygen is enhanced, and the turbulent flame propagation speed is increased.

[0023] See also Figure 3 The support plate 10 has a support plate frame 11, and the support plate frame 11 has hollow parts at the front edge and the main body of the support plate 10 for the corresponding porous wall panels 2 to be embedded therein; a booster cavity 4 is arranged between the inner and outer wall surfaces of the support plate 10, and the booster cavity 4 is arranged around the front edge and the main body of the support plate 10 and is internally connected; the booster cavity 4 has a diameter of 2 mm, and the cooling medium is transported from the fuel tank to the booster cavity 4 through the booster pump, and the sweating rate of the cooling medium is adjusted by the oxygen pump, so as to adjust the sweating cooling efficiency and the afterburning efficiency of the combustion chamber.

[0024] The support plate frame 11 is made of high-temperature titanium alloy, and the aperture of the fine flow channel in the porous wall plate 2 is between 10-100 microns.

[0025] The porous wall panel 2 is formed by metal powder injection molding. First, stainless steel 1Cr18Ni9Ti particles are mixed with an organic binder and then plasticized by high temperature heating. Then, the organic binder is sintered at a high temperature to volatilize the organic binder, and finally the porous wall panel 2 is formed.

Claims

1. A combustion chamber of a scramjet engine, characterized in that: The invention adopts kerosene as a cooling medium to realize phase change sweat cooling of the combustion chamber (7); the kerosene comes from the propellant of the scramjet engine and is stored in the hypersonic aircraft; the combustion chamber (7) has a support plate (10), the support plate (10) has a fixed wall surface (1) and a porous wall plate (2), the porous wall plate (2) is embedded and fixed in the fixed wall surface (1), and an increased capsule cavity (4) is arranged on the inner side of the porous wall plate (2), and the pressurized capsule cavity (4) can drive the cooling medium to pass through the The micro-flow channel in the porous wall plate (2) is then vaporized into the boundary layer (3) on the periphery of the fixed wall surface (1), forming a protective gas film (9). The heat flux density transferred from the high-temperature mainstream to the fixed wall surface (1) is reduced by the protective gas film (9), thereby achieving the purpose of cooling. In this process, the cooling medium takes away the heat of the fixed wall surface (1), and the heated cooling medium is circulated back to the propellant compartment of the scramjet engine, so that the propellant is preheated, thereby achieving the purpose of post-combustion of the scramjet engine.

2. The scramjet combustion chamber according to claim 1, characterized in that: In the scramjet engine, the airflow passes through the air inlet (5), the isolation section (6), the combustion chamber (7), and the tail nozzle (8) in sequence, and the above-mentioned phase change sweating cooling is completed in the isolation section (6); in the isolation section (6), the airflow and the cooling medium form a mixture, and the mixture forms a pre-combustion shock wave train. After passing through the pre-combustion shock wave train, the movement speed of the mixture decreases, the temperature and pressure increase, and the cooling medium is heated to achieve the purpose of preheating; at the same time, after the cooling medium stays in the isolation section (6) for a longer time, the mixing degree of the cooling medium and oxygen is enhanced, thereby improving the turbulent flame propagation speed.

3. The scramjet combustion chamber according to claim 2, characterized in that: The support plate (10) has a support plate frame (11), and the support plate frame (11) has hollow portions at the front edge and the main body of the support plate (10) for embedding corresponding porous wall panels (2) therein; a pressurized cavity (4) is arranged between the inner and outer wall surfaces of the support plate (10), and the pressurized cavity (4) is arranged around the front edge and the main body of the support plate (10) and is internally connected.

4. The scramjet combustion chamber according to claim 3, characterized in that: The boost chamber (4) has a diameter of 2 mm. The cooling medium is transported from the fuel tank to the boost chamber (4) through a boost pump, and the sweating rate of the cooling medium is adjusted by an oxygen pump, thereby adjusting the sweating cooling efficiency and the afterburning efficiency of the combustion chamber.

5. The scramjet combustion chamber according to claim 4, characterized in that: The support plate frame (11) is made of high-temperature titanium alloy, and the aperture of the micro-channel in the porous wall plate (2) is between 10 and 100 micrometers.

6. The scramjet combustion chamber according to claim 5, characterized in that: The porous wall panel (2) is formed by metal powder injection molding. First, stainless steel 1Cr18Ni9Ti particles are mixed with an organic binder and then plasticized by high temperature heating. Then, the organic binder is sintered at high temperature to volatilize the organic binder, and finally the porous wall panel is formed.

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