Mahmoud El Hajem

Drag reduction by pulsed jets on strongly unstructured wake: towards the square back control

Experimental studies have been performed in a wind tunnel in order to control the flow separation on rear window of a generic vehicle shape (the Ahmed body with a scale of 0.7 and a slope angle of 35 degrees). The rear part of the geometry has been modified by replacing the sharp edge between roof and rear window by smooth curved surfaces. This model is equipped at the end of the roof with a strip of pulsed jets in order to control the flow with a velocity of 30 m.s−1. A 20% drag reduction has been obtained with a pulsed frequency at 500 Hz and a momentum coefficient Cµ = 2.75 10−3. This result confirms the interest in using pulsed jets in order to reduce aerodynamic drag and pollutant emission.