CN103615741A - Heat protection method for injection support plate of scramjet engine by utilizing sweat and impingement cooling - Google Patents

Abstract

The present invention relates to a thermal protection method for the scram engine injection support plate by sweating and impact cooling, which includes the following contents: 1) The injection support plate with a microporous structure is made of a high temperature resistant material, A supporting rib is arranged in the plate to divide it into a front cavity and a rear cavity, and an impact hole connecting the front and rear cavities is arranged on the support rib, and the fuel pipe of the super-combustion engine is connected to the rear cavity of the injection support plate. Connected; 2) The process of using the fuel seeping out of the pores of the microporous structure to force convective heat transfer to take away the heat on the surface of the injection support plate, and to use the fuel seepage to form a film layer on the surface of the injection support plate , to block the heat transfer of the main flow to the injection support plate; 3) The fuel is injected from the rear cavity through the impact hole on the support rib to the inner surface of the front cavity, and convective heat exchange is performed with the inner surface of the front cavity. Support ribs in the strut strengthen the injection strut. According to the characteristics of porous media, the present invention uses fuel as a coolant and combines the concept of impingement cooling to realize the thermal protection effect on the injection support plate, and it can be widely used in the injection support of various Mach numbers. Plate thermal protection.

Description

Thermal Protection Method for Injection Slip Plate of Scram Engine by Sweating and Impingement 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 an injection support plate of a super-combustion engine by sweating and impact cooling in a high-temperature and high-speed airflow.

Background technique

A scramjet is a ramjet in which fuel is burned in a supersonic airflow. When hydrocarbon fuel is used, the flight Mach number of the scramjet engine is usually below 8, and when liquid hydrogen fuel is used, the flight Mach number can reach 6-25. As shown in Figure 1, the supersonic or hypersonic air flow is diffused and decelerated in the inlet section and the isolation section to a lower supersonic speed and enters the combustion chamber. Fuel is injected from the combustion chamber wall and/or protrusions in the air flow, mixed with air, and burned , the combusted gas is discharged through the expanding nozzle section. Since the residence time of the fuel in the combustion chamber is only a few milliseconds, the traditional way of injecting fuel on the wall of the combustion chamber has the disadvantage of short penetration distance, which makes it difficult to achieve effective mixing between the fuel and the high-speed mainstream, which affects the ignition and combustion of the fuel. .

The injection branch plate structure is a common device in the combustion chamber to realize the effective mixing of fuel and high-speed mainstream. The fuel is injected from the injection hole on the injection branch plate and mixed with the high-speed main flow to overcome the incident penetration The disadvantage of short distance, but at the same time, the stagnation of the hypersonic airflow on the surface of the injection strut will cause serious aerodynamic heating, and the injection strut, especially its leading edge, is extremely prone to ablation damage. It is estimated that the aircraft will fly at Mach number 8 When flying at an altitude of 27km, the total temperature of the high-temperature gas flowing through the combustion chamber can reach more than 3000K, which is close to the maximum cooling capacity of the forced convection cooling of the fuel currently used. A more effective active cooling method must be used to reduce the surface temperature of the injection support plate .

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 injection support plate of a scram engine by sweating and impingement cooling in a high-temperature and high-speed airflow.

In order to achieve the above object, the present invention adopts the following technical solutions: a thermal protection method for the injection support plate of a scram engine by sweating and impact cooling, which includes the following contents: 1) a microporous structure made of a high temperature resistant material The injection support plate is provided with a support rib that divides it into the front cavity and the rear cavity in the injection support plate. The support rib is provided with an impact hole connecting the front and rear cavities, and the fuel pipe of the super-combustion engine It communicates with the back cavity of the injection support plate; 2) The process of fuel seeping out of the microporous structure of the injection support plate pores is used to force convective heat exchange, taking away the heat on the surface of the injection support plate, and utilizing the fuel seepage A film layer is formed on the surface of the injection support plate to block the heat transfer of the main flow to the injection support plate; 3) The fuel is injected from the rear cavity through the impact hole on the support rib to the inner surface of the front cavity, and the inner surface of the front cavity Convective heat exchange is performed, and at the same time, the strength of the injection support plate is enhanced by using the support ribs in the injection support plate.

A number of 0.5mm oil injection holes are 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.

The impact holes on the support ribs are single or multiple rows, and the diameters of the impact holes are on the order of millimeters.

Said fuel adopts gaseous fuel or liquid fuel.

Metal powder with a diameter of micron scale and organic binder are uniformly kneaded, 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, and then chemically or thermally decomposed into the molded blank. The binder is removed, and the final product is obtained by 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 cooling needs. . 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, because 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 protection of the injection strut, especially its front edge, prevents the ablation damage of the injection strut. Tensile stress, so the structural strength of the injection strut can be increased to make up for the weakening of the strength caused by the use of loose and porous media to make the injection strut. 5. The present invention makes single row or multiple rows of impact holes on the supporting ribs, and connects the fuel pipes to the rear cavity of the injection support plate, so that the fuel is under pressure from the front and rear cavities from the multi-porosity of the wall. At the same time, it seeps out from the back cavity through the impact hole on the support rib, sprays on the inner surface of the front cavity, and has a strong convective heat exchange with the inner surface of the front cavity, which further enhances and improves the front edge of the injection support plate. Partial cooling. 6. Since the present invention sets the injection support plate into 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 the heat dissipation. protective effect. 7. According to the 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. 8. Since the method of the present invention adopts the sintering of stainless steel powder of about 90 microns to make a porous injection strut structure, many micron-scale pores are formed inside the fabricated injection strut structure, and the porosity is guaranteed to be 20%-30% Left and right, it can ensure the strength of the injection support plate 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 structure of a super-combustion engine

Figure 2 is a schematic diagram of the installation of the injection support plate of the present invention

Fig. 3 is a schematic diagram of the working principle of the injection support plate of the present invention

Fig. 4 is a schematic diagram of the structure of the rhombus injection support plate of the present invention

Figure 5 is a schematic cross-sectional view of Figure 4

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 scram engine 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 is set from the injection branch plate 2 according to the design requirements. It is sprayed out from the fuel 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 method of the present invention utilizes the concept of sweat cooling to use the fuel as a coolant Complete thermal protection of the outer surface of the injection strut.

As shown in Figure 3, the overall structural shape of the injection support plate 2 of the method of the present invention is similar to that of the prior art, including a strip-shaped cavity with a tapered front, one end of the cavity is a closed end, and the other end is passed through The lower base 3 is sealingly connected with an upper base 4 connected to the scram engine, and communicates with the fuel pipe 1 through a sealing steel plate 5 . The main features of the method of the present invention include: the first 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 released under pressure. Seep out from micropores; secondly, add a support rib 6 made of steel material or other high-temperature-resistant solid material in the cavity of the injection support plate 2, so that the injection support plate 2 forms two cavities, front and rear 7, 8, to share the tensile stress produced by the force on both sides of the injection support plate 2, effectively increase the strength of the injection support plate 2; thirdly, make single or multiple rows on the support rib 6 with a diameter of millimeter order , and communicate with the impact hole 9 of the front and rear cavities; the fourth connects the fuel pipe 1 to the rear cavity 8 of the injection support plate 2, so that the fuel can flow from the wall in the front cavity 7 and the rear cavity 8 under pressure. While seeping out of the micropores, it shoots out from the rear cavity 8 through the impact hole 9 on the support rib 6, sprays on the inner surface of the front cavity 7, and has a strong convective heat exchange with the inner surface of the front cavity 7. , the fuel seeps out from the pores on the wall of the front cavity 7 under the action of pressure.

The spraying support plate 2 with the 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: using metal powder with a micron-scale diameter (such as 90 microns) and organic adhesive The binder is mixed evenly, and after granulation, it is injected into the mold cavity with an injection molding machine to solidify under the state of heating and plasticization, and then the binder in the forming blank is removed by chemical or thermal decomposition, and it is sintered and compacted. into the final product. In the present invention, many micron-scale pores are formed on the wall surface of the injection support plate produced by the microporous production process, the porosity can be guaranteed to be about 20%-30%, the production precision is high, the micropore structure is uniform, and the performance is excellent.

In the above-mentioned embodiments, since the injection support plate 2 is usually designed so that the front edge line is perpendicular to the incoming flow direction of the main flow, due to the stagnation of the main flow at the front 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. 4 and Fig. 5, in order to solve this problem, the present invention designs the injection strut plate 2 as an inclined rhombus structure, so that the inclination direction of the front edge of the injection strut 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 of about 0.5mm can also be opened on the injection support plate 2 as required in the prior art. However, due to the existence of the microporous structure of the present invention, the injection The injector plate 2 will significantly alleviate the problems of 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 thermal protection method utilizing sweating and shock cooling to the injection support plate of a scram engine, which comprises the following contents: 1) The injection strut plate with microporous structure is made of high temperature resistant material, and a support rib is set in the injection strut plate to divide it into the front cavity and the rear cavity. The impact hole of the cavity communicates the fuel pipe of the scram engine with the rear cavity of the injection support plate; 2) Use the process of fuel seeping out of the microporous structure of the injection support plate to force convective heat exchange, take away the heat on the surface of the injection support plate, and use the fuel seepage to form a film layer on the surface of the injection support plate to block Heat transfer from the main flow to the injection support plate; 3) The fuel is sprayed from the rear cavity to the inner surface of the front cavity through the impact hole on the support rib, and convective heat exchange is performed with the inner surface of the front cavity, and at the same time, the support rib in the injection support plate is used to enhance the injection support strength. 2. The thermal protection method for the injection support plate of a scram engine by sweating and impact cooling as claimed in claim 1, characterized in that: the injection support plate is provided with a plurality of 0.5mm oil injection holes. 3. The thermal protection method for the injection strut plate of the super-combustion engine by sweating and impact cooling as claimed in claim 1, characterized in that: the external shape of the injection strut plate is an oblique angle with the main flow direction rhombus. 4. The thermal protection method for the injection strut plate of the super-combustion engine by sweating and impact cooling as claimed in claim 2, characterized in that: the external shape of the injection strut plate is an oblique angle with the main flow direction rhombus. 5. The thermal protection method of injection support plate of a scram engine by sweating and impact cooling as claimed in claim 1 or 2 or 3 or 4, characterized in that: the impact holes on the support ribs are single row or multiple row, and the diameter of the impact hole is on the order of millimeters. 6. The thermal protection method for injection strut plate of scram engine by sweating and shock cooling as claimed in claim 1 or 2 or 3 or 4, characterized in that: said fuel is gaseous fuel or liquid fuel. 7. The thermal protection method for injection strut plate of scram engine by sweating and shock cooling as claimed in claim 5, characterized in that: said fuel is gaseous fuel or liquid fuel. 8. The thermal protection method for injection strut plate of a scram engine by sweating and impact cooling as claimed in claim 1 or 2 or 3 or 4 or 7, characterized in that: metal powder with a diameter of micron scale and organic adhesive The binder is mixed evenly, and after granulation, it is injected into the mold cavity with an injection molding machine to solidify under the state of heating and plasticization, and then the binder in the forming blank is removed by chemical or thermal decomposition, and it is sintered and compacted. into the final product. 9. Utilize perspiration and shock cooling as claimed in claim 5 to the thermal protection method of scram engine injection support plate, it is characterized in that: adopt the metal powder of micron order diameter and organic binder to knead evenly, after making After granulation, it is injected into the mold cavity with an injection molding machine to solidify and form 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. 10. The method for heat protection of the injection strut plate of the super-combustion engine utilizing sweating and impact cooling as claimed in claim 6, characterized in that: the metal powder and the organic binder are evenly mixed and kneaded with a micron-scale diameter, and the prepared After granulation, it is injected into the mold cavity with an injection molding machine to solidify and form 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.

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