Numerical evaluation of shock wave effects on turbulent mixing layers in a scramjet combustor

Abstract

ABSTRCT The effects of shock waves on turbulent mixing layers in a supersonic combustor are investigated. An asymmetric scramjet combustor with strut designed and tested by German Aerospace Center is taken as the physical model. Then Reynolds-averaged Navier-Stokes numerical simulations of the non-reacting cold flow field are carried out. The results demonstrate that the mixing zone containing two mixing layers exhibits a complex thickness variation under the actions of multiple shock waves. In this variation, the thickness decrease at shock wave action positions can be quantitatively characterized by the relative decrease of thickness of mixing layers, while the recovery of thickness increase in the vicinities downstream of shock wave action positions can be quantitatively characterized by the slope increase of thickness variation curve of mixing layers. Both of these characterization parameters are positively correlated with the shock intensity. The physical mechanism of the thickness decrease at the shock wave action positions is that shock waves cause density increase which then lead the thickness to decrease. The physical mechanism of the recovery of thickness increase in the vicinities downstream of the shock wave action positions is that shock waves induce vorticity enhancement which then results in the thickness growth rate to increase.