Effect of film cooling injection on aerodynamic performances of scramjet isolator

With continuous increase in flight Mach number, aerodynamic heating on scramjet isolators becomes increasingly pronounced. Consequently, a thermal protection technique for scramjet isolators is urgently required. In the present study, a numerical investigation was conducted to evaluate the feasibility of applying film cooling on a scramjet isolator. First, the heat transfer characteristics under different coolant flow conditions (i.e., coolant Mach number, coolant total temperature, and injection position) were obtained to evaluate the film cooling efficiency on a scramjet isolator. Next, the characteristics of maximum backpressure and friction drag were analyzed to obtain the effects of film cooling injection on the aerodynamic performances of the scramjet isolator. It was found that the film cooling injection under proper coolant flow conditions could reduce the friction drag and enhance the ability of the isolator to resist backpressure, which is beneficial to the performances of a scramjet engine. In general, the results obtained in this study indicated that film cooling injection could be a practical thermal protection technique for a scramjet isolator.