Turbulent Boundary Layer Synthetic Jet Interaction: Slot Inclination Effects

Abstract

The present paper deals with synthetic jet actuators. The synthetic jet actuator is a low power, highly compact fluidic system and efficient to control a boundary layer. In this study, the development of synthetic jet is first analysed and characterized then its interaction with boundary layer along a flat plate is studied. The designed actuator is used in a wind tunnel. Different inclinations of the jet are investigated for a fixed forcing frequency (60 Hz). Both hot wire anemometer and the Particle Image Velocimetry (PIV) are used. First, the synthetic jet normal to the wall without cross flow is characterised. The inclination effect is then examined. The same situations are studied in presence of cross flow. For the normal jet, the PIV results show a decrease of the mean wall velocity. The phase-averaged velocity profiles revealed that spanwise large-scale vortices are generated downstream of the slot and persist farther downstream. The inclination of the synthetic jet has an important effect on the expansion of the jet. It has been observed that the interaction with the wall modify strongly this expansion. The modification induced by the jet angle variation will be analysed in details in this paper. We will focus on the wall behaviour.