Physical insight into fuel mixing enhancement with backward-facing step for scramjet engines via multi-objective design optimization

Fuel injection into crossflow behind a backwardfacing step is studied by means of multi-objective design optimization, aiming at fuel/air mixing for supersonic combustion of scramjet propulsion. A variety of injector configurations have been examined in the optimization process using evolutionary algorithms in conjunction with local search methods and surrogate modeling. Data mining has been performed by applying statistical techniques including variance-based sensitivity analysis to the surrogate models constructed with solutions from computational fluid dynamics. The injection angle and backward step height have been found to be the most influential design parameters on the mixing performance for the configurations considered in this study.