Active control of turbulent flow separation over a backwardfacing step using acoustic tube.

Abstract

flow and the effect was investigated experimentally. Different periodic perturbations were introduced into the turbulent shear flow. Planar particle image velocimetry (PIV) was employed to measure the separated flow as well as the reattachment area downstream. The time-averaged and phase-averaged flow fields were obtained and the Reynolds stresses in clean and controlled cases were compared. It has been shown that in the controlled case the flow separation was suppressed and the reattachment length was reduced by as much as 47.6%. Furthermore, The method of proper orthogonal decomposition (POD) was applied to the flow fields to extract large-scale coherent flow structures. The resulting phase-averaged motions of main POD modes provides more insight into the evolution of the shedding vortices as well as the interaction between the mean and oscillating flow fields.