INVESTIGATION OF CHARACTERISTICS OF SHEAR LAYER: APPLICATION OF SYNTHETIC JET IN BACKWARD-FACING STEP FLOW FIELD

Abstract

The purpose of this research is to explore the two-dimensional backward-facing-step flow perturbed by a synthetic-jet actuator experimentally. The step was placed in a low-speed wind tunnel and the flow passage expansion ratio was 1.07. The Reynolds number was Reh = 1.18 × 104 based on the step height and the upstream velocity before the step edge. An electromagnetic loudspeaker was used to generate synthetic jet flows in the direction of the main flow through a slot of 1 mm in width. The peak value of the driven AC voltage was 8 V and the frequency varied in the range of 80–120 Hz. The velocity of the flow field was measured by hot wire anemometers. The distributions of averaged velocity, fluctuation intensity, and Reynolds stress were analyzed to understand the influences of the synthetic jet. The characteristic frequencies were also obtained. The size of the recirculation region was affected by the synthetic jet. The downstream reattached flow was more stable with the synthetic-jet perturbation.