Vorticity Transport in Different Regions of a Strut-Based Scramjet

A hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation investigation of a strut-based scramjet is performed in the present paper. Both nonreacting and reacting cases in which the same sonic fuel jet mixes/reacts with two different supersonic airstreams (T = 340 Kvs T = 850 K) are comparatively studied. The vorticity and its influencing factors are analyzed to understand the transport behaviors in the scramjet. Multiple mechanisms contribute to vorticity simultaneously but unequally in different regions. A large part of the flowfield is full of the supersonic airstream with small vorticity. In the mixing region, the averaged vorticity magnitude decreases gradually along the chamber length, and vortex stretch is the leading mechanism of vorticity transport within this region. The baroclinic torque effect is strengthened dramatically by combustion, but is weakened by the incoming flow with higher stagnation enthalpy. Although the near-wall region is small, the averaged vorticity magnitude in this region is extremely large due to the confinement and viscosity effects. Diffusion is the leading mechanism in the near-wall region, but dilatation can dominate vorticity transport due to shock-wave/boundary-layer interaction and pressure rise resulting from combustion.