EFFECTS OF NOZZLE EXIT GEOMETRY ON FOREBODY VORTEX CONTROL USING BLOWING

An experimental study has been undertaken to examine the influence of the blowing nozzle exit geometry on the effectiveness of the aft blowi ng technique for forebody vortex control. The experiments were conduct ed with a 3.0-caliber tangent ogive model at subsonic velocities and a Reynolds number of 8.4 X 10(4) based on the model diameter. Asymmetri c aft blowing was accomplished using both a single nozzle and a double nozzle configuration. Detailed surface pressure measurements on the m odel were obtained and local side forces determined. The experimental results show that both the height and the width of the blowing nozzle exit geometry are important parameters that determine the effectivenes s of aft blowing; a broad, low-positioned blowing nozzle exit geometry is found to be most effective for the forebody vortex control techniq ue using aft blowing.