Secondary Flows and Separation in S-Duct Diffusers: Their Detection and Control

Abstract

An experimental investigation was undertaken to detect and control secondary flows and separation in two-dimensional Sduct diffusers. Active control by vortex generator jets was applied to control secondary flows. The experiments were carried out with and without inflow distortion. Detailed measurements including total pressure and velocity distribution, surface static pressure, skin friction and boundary layer measurements were taken at an inlet Reynolds number of 7.8 × 105. These measurements are presented here along with static pressure rise, distortion coefficient, total pressure loss coefficients and the transverse velocity vectors at the duct exit determined from the measured data. Substantial improvement in static pressure rise and flow quality was achieved by the use of vortex generator jets.