Characteristics of gaseous film cooling with hydrocarbon fuel in supersonic combustion chamber

With the increasing altitude and speed of the hypersonic vehicles, the temperature of the combustion chamber wall must be substantially decreased to ensure thermal and structural reliabilities. As a great supplement to the main regenerative cooling method without additional coolant, film cooling with onboard hydrocarbon fuel is widely used to decrease the wall heat flux. In this paper, a typical cylindrical film injection hole is employed to study the flow and heat transfer characteristics of gaseous film cooling with hydrocarbon fuel in the supersonic main flow, and the effects of transverse-non-uniform distributions of blowing ratio and injection angle are analyzed in detail. The results show that entrainment process between cooling films with different blowing ratios and injection angles would influence the film cooing efficiency to different degree, and proper combination of these two factors can improve the film cooling efficiency and decrease the flow rate of the cooling film. And the empirical correlation of supersonic hydrocarbon film cooling efficiency is established for the uniform blowing ratio cases. For the transverse non-uniform blowing ratio, the overall cooling efficiency decreases due to the spanwise and height-wise ejections between the two groups of cooling film. And for the cases with combination of transversely non-uniform blowing ratio and unequal injection angle, the film cooling effectiveness per blowing ratio would increase by 8.0%.