Numerical Study On Film Cooling Of The Hypersonic Inlet

Hypersonic inlet is an important part of the scramjet, and its serious aerodynamic heating is one of the most critical problems for hypersonic inlet design. For the active film cooling is deemed as one of the ideal thermal protection measures for the surface of high-speed or hypersonic vehicle, studies on the flow and heat transfer characteristics is significant to effectively protect the inlet and provide guidelines for the inlet design. In this paper, the research is based on the simplified inlet experimental model and the experimental data of the ShockWave laboratory of the RWTH Aachen, Germany. Using the results of numerical calculation and the discussion on the cooling gas mass flow and the main parameters that influence the cooling effectiveness, we analyze the characteristics and factors affecting the film cooling flow field of hypersonic inlet.Compared with the experimental results, the simulation value is close to the experimental value. Thus, the result is credible.The factors that influence the cooling effectiveness include blow ratio, slot width, blowing angle, the specific heat ratio of the cooling medium to the freestream gas, the unit Reynolds number of the freestream, larger running lengths, the Mach number of the freestream, temperature and so on. By analyzing these factors the following can be concluded:In the hypersonic, film cooling in the laminar flow is an effective method to reduce the thermal load for ariframe, and it requires less cooling gas mass flow. In the research scope of this paper, when the other parameters are constant, the cooling effectiveness increases with the increase of blow ratio, slot width, the unit Reynolds number of the freestream, larger running lengths, the Mach number of the freestream and temperature, and decreases with the increase of the distance from the center of the blowing opening, coolant gas and the specific heat ratio of the cooling medium to the freestream gas respectively. When the blow ratio is lower (F<0.065), the cooling effectiveness is constant while the blowing angle increases. And when the blow ratio is higher (0.065<F<0.13), the cooling effectiveness increases with the increase of the blowing angle;As for double row slot, the cooling effectiveness of double row slot structure under the condition of low blow ratio is roughly equal to that of single slot structure under the condition of big blow ratio.