Flow Control around an Ahmed Body using Synthetic jets

Abstract

The effects of synthetic jet array on the aerodynamic drag of a simplified car model is experimentally investigated. Experimental model is an Ahmed body with a rear slant angle of 25° scaled at 0.2 of the original Ahmed model. Synthetic jets are produced by periodic ejection and suction of fluid from an orifice induced by movement of a diaphragm inside a cavity. Aerodynamic force measurements were performed by changing the jet-to-freestream velocity ratio, jet frequency and jet orifice locations. In this experiment, two jet positions are tested to investigate the effect of the jet location on drag reduction. The jet orifices had a diameter of 2 mm, and eight circular orifices were arranged at equal intervals in the spanwise direction. In the flow visualization with a smoke wire method, the suppression of flow separation was confirmed. Drag reductions up to 7% were attained when the jet orifice location was on the slanted surface and it was also confirmed that the drag reduction was affected by the jet orifice location.