Separation Control over Stator Vanes with Backward-Facing Step Using Synthetic Jets

Abstract

Control of flow separation over stator vanes with backward-facing step applying synthetic jets (zero net mass flux) is investigated using particle image velocimetry (PIV). The stator vanes are fixed at an angle of -10° to the main flow with Reynolds number of 2.7×103, which is produced by a small ducted fan. Without synthetic jets, the flow separates at the edge of the step and the shear layer glows in width along to the downstream, the flow reattachment is achieved at near the trailing edge. In contrast, with synthetic jets actuating on Cμ =4.5×10-2 and F+=1.46, high momentum and high actuation frequency for conventional backward-facing step flow control, the flow is directed immediately to the lower step near the synthetic jet orifice and reattachment length is shortened by 53% of no-flow control case. Phase-locked data shows the vortices of synthetic jets dominate the flow filed of upstream and downstream of the step. The shear layer is completely overcasted with the strong vortices of the synthetic jets, and furthermore, the recirculation bubble is controlled by the separated vortices of synthetic jets resulting recirculation region smaller.