VORTEX ASYMMETRY AND INDUCED SIDE FORCES ON ELLIPTIC CONES AT HIGH-INCIDENCE

Experimental studies were carried out investigating features of vortex asymmetry and induced side forces on a family of three elliptic cones at subsonic speeds. Measurements of forces, moments, and surface now visualization studies were made up to an angle of attack of 45 deg ove r a wide range of Reynolds number. Results show that ellipticity progr essively reduces the angle of attack for the onset of side force up to an ellipticity ratio (defined here as the ratio of major to minor axi s) of 1.43, beyond which there is a reversal in this trend for both ho rizontal as well as vertical orientations of the ellipse. Interestingl y, the (maximum) side force magnitudes are larger for the horizontal c ompared to the vertical ellipse orientation on each model. A correlati on of the angle of attack for the onset of asymmetry on pointed forebo dies with elliptic cross section is suggested. These results provide s trong support to the hypothesis (often made in the literature) that in viscid mechanisms may play a key role in triggering asymmetry of vorte x flows.