A circulation prediction model for ramp and vortex generator in supersonic flow: A numerical study

Abstract

The circulation growth of supersonic streamwise vortex (SSV) formed by a ramp is complicated and essential to estimate scramjet mixing behavior, while a predictive model for circulation growth is still lacking. Through well-validated RANS simulations, it is observed that the circulation growth of streamwise vortex for a ramp is similar to one for vortex generator, which determines three important geometric parameters for SSV growth, i.e., ramp angle, swept angle, and length of the leading edge. The results of different geometries with these three parameters further show that the SSV circulation growth is proportional to the downwash speed influenced by oblique shock intensity. By building the relation between downwash speed and geometric parameters, an SSV circulation prediction model is proposed and validated by the circulation curves of all cases under a wide range of free stream Mach numbers. The novel circulation model has the potential for the preliminary mixing enhancement design for a scramjet ramp injector.