CN103672966B - Thermal protection method for scramjet engine fuel injection supporting plate by utilization of transpiration cooling - Google Patents

Abstract

The invention relates to a thermal protection method for fuel injection struts of super-combustion engines by sweat cooling, which includes the following contents: 1) The injection struts with microporous structures are made of high-temperature-resistant materials, and the super-combustion engine The fuel pipe is connected with the injection support plate; 2) The process of fuel seeping out of the microporous structure of the injection support plate is used to force convective heat exchange to take away the heat on the surface of the injection support plate; 3) The fuel seepage A film layer is formed on the surface of the injection support plate to block the heat transfer from the main flow to the injection support plate. In the present invention, a multi-porous structure is made on the injection support plate material, and the concept of sweat cooling is used to use the fuel as a coolant, so that the fuel flows through the injection support plate and undergoes strong convective heat exchange with the injection support plate. At the same time, the fuel forms a thin layer on the surface of the injection support plate, which hinders the heat transfer between the high-temperature main flow and the surface of the injection support plate, and realizes the thermal protection of the injection support plate, especially its front edge, and prevents the injection support plate from burning. Corrosion damage. The invention can be widely used in the heat protection of various ramjet injection support plate structures.

Description

Thermal Protection Method of Fuel Injection Slip Plate in Scram Engine Using Sweat Cooling

technical field

The invention relates to a thermal protection method for a high-temperature wall surface, in particular to a thermal protection method for a fuel injection support plate of a super-combustion engine by sweating and cooling in a high-temperature and high-speed airflow.

Background technique

As an aerospace technology that represents the frontier of modern science and technology development, due to its significance in national defense and space resource utilization, it has received great investment from many countries in the world and has driven the prosperity and development of related industries. In order to meet the higher and faster requirements of flying, the development of new and efficient engine technology has become an inevitable development of future aerospace vehicles. As shown in Figure 1, the ramjet engine is a type of engine that does not have a complex blade structure that rotates at high speed, and realizes the deceleration and compression of high-speed incoming air through the intake port. In order to achieve hypersonic (Ma>5, Ma is the Mach number) cruising flight in the atmosphere, the flow and combustion of the main flow and combustion of the combustion chamber in the engine need to be carried out at hypersonic speed, and the high-speed main flow of the high Mach number flow first passes through the front edge of the aircraft and the inlet. The oblique shock wave is generated in the section to decelerate and compress, and then enters the combustion chamber through the weak shock wave train in the isolation section, mixes with the injected fuel, ignites, burns, and finally sprays out through the nozzle section to provide power. However, the residence time of the fuel in the combustion chamber is only a few milliseconds, and an efficient device is needed to provide the fuel injection to achieve the mixing between the fuel and the high-velocity main flow.

The injection branch plate structure is a common device in the combustion chamber to realize the effective mixing of fuel and high-speed main flow. The fuel is sprayed from the injection hole on the injection support plate and mixed with the high-speed main flow, which overcomes the incident penetration distance of the wall surface. short downside. However, at the same time, the high-speed mainstream stagnates on the surface of the injection strut, resulting in severe aerodynamic heating. The injection strut, especially the leading edge, is prone to ablation damage. Effective active cooling must be used to reduce the surface temperature of the injection strut.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a thermal protection method for the fuel injection support plate of the super-combustion engine by sweat cooling in the high-temperature and high-speed airflow.

In order to achieve the above object, the present invention adopts the following technical solutions: a method for thermally protecting the fuel injection support plate of a super-combustion engine by sweating and cooling, which includes the following contents: 1) A nozzle with a microporous structure is made of a high-temperature-resistant material Injection support plate, and connect the fuel pipe of the super-combustion engine with the injection support plate; 2) Use the process of fuel seeping out of the microporous structure injection support plate pores to force convective heat exchange, and take away the surface of the injection support plate 3) The fuel seeps out to form a film layer on the surface of the injection support plate to block the heat transfer from the main flow to the injection support plate.

Support ribs of high-temperature-resistant solid material are arranged in the cavity of the injection support plate, and each cavity separated by the support rib communicates with a fuel pipe respectively.

The supporting rib is the one arranged in the middle of the cavity.

The supporting ribs are arranged in multiple intervals in the cavity.

An oil injection hole is opened on the injection support plate.

The outer shape of the injection support plate is a rhombus with an oblique angle to the main flow direction.

When the metal powder is used to make the porous injection support plate, the micron-sized metal powder and the organic binder are uniformly kneaded first, and after granulation, they are injected into the mold cavity with an injection molding machine in a heated and plasticized state to solidify and form. Then chemical or thermal decomposition method is used to remove the binder in the molded body, and the final product is obtained through sintering and densification.

The present invention has the following advantages due to the adoption of the above technical scheme: 1. According to the characteristics of the porous medium, the method of the present invention produces a porous structure on the injection support plate material, and utilizes the concept of sweating and cooling, which not only can realize the separation of the fuel and the mainstream It is better mixed, and the fuel is used as a coolant to complete the thermal protection of the outer surface of the injection support plate. It has a large cooling capacity. From the perspective of thermal protection, only a low amount of fuel is required to meet the needs of use. . 2. Due to the presence of a large number of pores inside the injection support plate of the present invention, the specific surface area is very large, so when the fuel flows through the injection support plate, strong convective heat exchange occurs with the injection support plate, which can effectively absorb solid waste. Heat, reduce the injection support plate temperature. 3. In the present invention, since the fuel penetrates into the main flow through the pores of the injection support plate at a relatively slow speed, a thin layer will be formed on the surface of the injection support plate, which hinders the heat transfer between the high-temperature main flow and the surface of the injection support plate, and realizes the The injection strut, especially the protection of its front edge, prevents the ablation damage of the injection strut. 4. Since the present invention adds support ribs in the cavity of the injection support plate to share the tensile stress generated by the force on both sides of the injection support plate, it can increase the structural strength of the injection support plate and make up for the use of loose and porous media to make the injection support plate. The weakening of the strength caused by the support plate. 5. In the present invention, since the injection support plate is arranged in a rhombus structure, the inclination angle between the injection support plate and the incoming flow direction can be adjusted according to actual needs, so that the stagnation effect of the main flow on the surface of the injection support plate is weakened, further improving Thermal protection effect. 6. According to flight requirements, the present invention can also open fuel injection holes with a diameter of about 0.5 mm on the injection support plate on the basis of the injection support plate of the present invention to increase the fuel injection amount, The cooling efficiency is further improved without the problem that the prior art does not have multiple pores. 7. The method of the present invention adopts the sintering of micron-scale stainless steel powder to make a porous injection strut structure, so it can ensure the strength of the injection strut while allowing the fuel to flow through the micropores, and withstand a certain fuel inlet pressure. The invention can be widely used in the heat protection of various ramjet injection support plate structures.

Description of drawings

Figure 1 is a schematic diagram of the working principle of a supercombustion engine

Fig. 2 is the schematic diagram of the connection between the injection support plate and the existing equipment in the present invention

Figure 3 is a schematic diagram of the end face structure of the injection support plate in Figure 2

Fig. 4 is a top sectional schematic diagram of Fig. 3

Fig. 5 is a schematic diagram of the structure of the injection support plate of the present invention with steel-based support ribs added

Fig. 6 is a schematic diagram of the structure of the rhombus injection support plate of the present invention

Figure 7 is a schematic cross-sectional view of Figure 6

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1 and Figure 2, in a scram engine, aviation kerosene or liquid hydrogen is generally selected as the fuel according to the different flight Mach number ranges of the aircraft. In some special working environments, gaseous fuel is also used. The fuel is controlled by the pump carried by the super-combustion generator itself and the valve set on the fuel channel. After reaching a certain pressure, it enters the injection branch plate 2 through a fuel pipe 1, and flows from the injection branch plate 2 according to the design requirements. It is sprayed out from the set oil injection hole, mixed with the mainstream of high-temperature and high-speed airflow, and then burned to provide power. The structure of the method of the present invention is basically the same as that of the prior art, and the difference is that the present invention improves the material and structure of the injection support plate. According to the characteristics of the porous medium, the present invention utilizes the concept of sweat cooling and uses the fuel as a coolant to complete the process. Thermal protection of the outer surface of the injector strip.

As shown in Figures 3 and 4, the overall structural shape of the injection support plate 2 of the present invention is similar to that of the prior art, including a strip-shaped cavity 22 with a front portion 21 tapered, and one end of the cavity 22 is closed. End 23, and the other end is sealed and connected with an upper base 4 connected to the super-combustion generator through the lower base 3, and is sealed and connected with the fuel pipe 1 through a sealing steel plate 5, so that the fuel pipe 1 communicates with the injection branch plate 2. The main feature of the inventive method is that the wall material of the injection support plate 2 is set to a microporous structure, that is, the wall surface of the entire injection support plate 2 is covered with micropores, and the fuel can be discharged from the micropores under the action of pressure. Oozing out of the pores. The injection support plate 2 of the multi-microporous structure of the present invention can be obtained by using various high-temperature-resistant materials and various processing techniques in the prior art, such as: uniformly kneading micron-scale metal powder and organic binder, After granulation, it is injected into the mold cavity with an injection molding machine to solidify and formed in a heated and plasticized state, and then the binder in the formed blank is removed by chemical or thermal decomposition, and the final product is obtained through sintering and densification. The spraying support plate 2 produced by the microporous production process of the present invention has high production precision, uniform microporous structure and excellent performance.

The present invention utilizes the huge specific surface area inside the injection branch plate 2 with a microporous structure, so that the fuel filled in the cavity of the injection branch plate 2 can seep out from the micropores under the action of pressure, and it is compatible with the injection branch plate. The surface of the plate 2 conducts strong convective heat exchange, thereby effectively taking away the heat of the solid injection support plate 2 . At the same time, due to the action of the main flow, the fuel will be resisted when it seeps out of the micropores of the injection branch plate 2, and the fuel flow rate is not very high, so the leaked fuel will form a stagnant cover on the surface of the injection branch plate 2, thickening The boundary layer of the fluid is formed, which plays a role in hindering the heat transfer of the high-temperature gas to the wall surface of the injection support plate 2. In addition, since the fuel seeps out from the micropores on the surface of the injection branch plate 2, it mixes with the high-temperature and high-speed main flow, heats up, and starts to burn after reaching the ignition point, so it can be considered that the fuel passes through the microporous injection branch plate 2. It goes deep into the inside of the mainstream, so that the fuel that continuously seeps out from the micropores can achieve a better blending effect with the mainstream.

In the above-mentioned embodiment, in order to overcome the flow resistance in the micropores, the pressure of the fuel injected into the cavity of the injection strut 2 is usually greater than the external mainstream ambient pressure, and a certain tensile stress will be generated inside the two sides of the injection strut 2 ; At the same time, the microporous structure will weaken the injection strut 2 to a certain extent. As shown in Figure 5, in order to solve this problem, the present invention adds a support rib 6 made of a steel material or other high-temperature-resistant solid material in the cavity of the injection support plate 2, and the support rib 6 can be arranged at the injection Near the middle of the cavity of the support plate 2, the injection support plate 2 forms two front and rear cavities 7, 8 to share the tensile stress generated by the force on both sides of the injection support plate 2 and effectively increase the injection support. Strength of plate 2. After taking this measure, a fuel pipe 1 needs to be provided respectively for the two cavities 7, 8, that is to say, fuel is fed in respectively. Of course, the present invention can also add more supporting ribs 6 in the cavity of the injector support plate 2 and arrange more fuel pipes 1 to connect different cavities as required.

In the above embodiment, since the injection support plate 2 is usually designed so that the edge line of the front part 21 is perpendicular to the incoming flow direction of the main flow, due to the stagnation of the main flow at the leading edge, the flow velocity is zero, the static pressure and temperature are the largest, and the thermal environment is harsh At the same time, it is not conducive to fuel seepage, so it is more difficult to protect the injection support plate 2 from heat. As shown in Fig. 6 and Fig. 7, in order to solve this problem, the present invention designs the injection support plate 2 as an inclined rhombus structure, so that the inclined direction of the front edge of the injection support plate 2 forms an acute angle with the incoming flow direction. In this way, in some special working environments, such as aircraft using gaseous fuel, the specific heat capacity of the fluid is small, the main flow velocity and aerodynamic heating are particularly high, and the cooling capacity of the dangerous area at the front edge of the injection support plate 2 is insufficient. The injection strut 2 of the structure is designed so that when the main flow reaches the leading edge, the fluid can still flow along the outer surface of the injection strut 2, thus weakening the stagnation effect of the main flow and improving the flow rate of the injection strut 2. Protection of the dangerous part of the leading edge.

In the above-mentioned embodiment, in order to increase the fuel injection rate, some oil injection holes (not shown in the figure) of about 0.5 mm can also be opened on the injection branch plate 2 as required in the prior art, but due to the multiple With the existence of the microporous structure, the injection strut 2 will obviously alleviate the problems existing in the prior art.

The above-mentioned embodiments are only used to illustrate the present invention, wherein the manufacturing process and external structure of the injection support plate can be changed, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not be used. excluded from the protection scope of the present invention.

Claims (10)

1. a kind of thermal protection method that utilizes sweat cooling to fuel injection support plate of super-combustion engine, it comprises the following content: 1) A microporous injection support plate is made of a high temperature resistant material, and the fuel pipe of the super-combustion engine is connected with the injection support plate; 2) Utilize the process of fuel seeping out of the pores of the microporous structure of the injection support plate to force convective heat transfer to take away the heat on the surface of the injection support plate; 3) A film layer is formed on the surface of the injection support plate by fuel seepage to block the heat transfer of the main flow to the injection support plate. 2. the method for thermal protection of super-combustion engine fuel injection strut by perspiration cooling as claimed in claim 1, characterized in that: the cavity of the injection strut is provided with a support rib of high-temperature-resistant solid material, And each cavity separated by the supporting ribs communicates with a fuel pipe respectively. 3. The thermal protection method for the fuel injection support plate of the super-combustion engine by sweat cooling according to claim 2, characterized in that: the support rib is one arranged in the middle of the cavity. 4. The thermal protection method for the fuel injection support plate of the super-combustion engine by sweat cooling according to claim 2, characterized in that: the support ribs are a plurality of which are arranged at intervals in the cavity. 5. The thermal protection method for the fuel injection support plate of a super-combustion engine by sweat cooling as claimed in claim 1, 2, 3 or 4, characterized in that: the injection support plate is provided with an oil injection hole. 6. The thermal protection method of the fuel injection strut plate of the super-combustion engine utilizing sweat cooling as claimed in claim 1 or 2 or 3 or 4, characterized in that: the external shape of the injection strut plate is to flow with the main flow The direction is a rhombus with an oblique angle. 7. The method for thermal protection of fuel injection struts of super-combustion engines utilizing sweat cooling as claimed in claim 5, characterized in that: the external shape of said injection struts is at an angle of inclination with the main flow direction diamond. 8. as claimed in claim 1 or 2 or 3 or 4 or 7, utilize sweating cooling to the thermal protection method of super-combustion engine fuel injection strut plate, it is characterized in that: when adopting metal powder to make porous injection strut plate, Firstly, the micron-scale metal powder is uniformly mixed with an organic binder, and after granulation, it is injected into the mold cavity with an injection molding machine in a heated and plasticized state to solidify, and then chemically or thermally decomposed. The binder is removed, and the final product is obtained by sintering and densification. 9. utilize sweat cooling as claimed in claim 5 to the thermal protection method of super-combustion engine fuel injection strut, it is characterized in that: when adopting metal powder to make porous injection strut, first the metal powder of micron scale Mix it evenly with the organic binder, inject it into the mold cavity with an injection molding machine to solidify after granulation, and then remove the binder in the molded blank by chemical or thermal decomposition, and pass through Sintering densification yields the final product. 10. The thermal protection method of utilizing sweat cooling to fuel injection struts of super-combustion engines as claimed in claim 6, characterized in that: when metal powders are used to make porous injection struts, first the micron-scale metal powders Mix it evenly with the organic binder, inject it into the mold cavity with an injection molding machine to solidify after granulation, and then remove the binder in the molded blank by chemical or thermal decomposition, and pass through Sintering densification yields the final product.