Origin of Ring-like Vortices in the MVG Controlled Turbulent Boundary Layer

Abstract

In this paper, the origin of ring-like vortices which are found behind the MVG controlled supersonic flow is studied. It is verified that the ring-like vortices can come from the upstream vortex structure and be generated by the shear layer instability at the boundary of the momentum deficit as well. However, if the inflow in front of the MVG is fully developed turbulent flow, the lower boundary layer underneath the ring-like vortex structure would influence the formation of the vortex rings a lot. Furthermore, it is also found that certain vortex structure in the lower boundary layer can be lift up and become the ring-like vortex. The formation and development of the ring-like vortices is more complicated under the consideration of the influence of the fully developed turbulent inflow.