Interaction of Synthetic Jet with Diffuser Separation Flow in Low Reynolds Number

Abstract

The present paper describes a synthetic jet interaction with the diffuser flow in low Reynolds number. The flow visualization and the measurement of the wall static pressure are conducted. The flow regimes are three cases; the turbulent flow, the transitory flow and the laminar flow. The flow separation without the synthetic jet in the transitory and laminar flow regimes becomes severer than that in the turbulent regime. The separated flow does not have the intermittency and the separating shear layer is steady. The synthetic jet has a diameter of 0.5 mm and a frequency of 20, 50 and 100 Hz. The synthetic jet promotes a breakdown of the vortex structure in the separating shear layer and the mixing between the main stream and the separation bubble. In addition, the synthetic jet promotes the reattachment of the separating flow and improves the pressure recovery. On the other hand, the synthetic jet does not have the effect on the detachment point. The jet frequency has the range to introduce the vortex structures in the shear layer, and the range depends on the Reynolds number.