Suppression of vortex asymmetry and side force on a circular cone

Abstract

An experimental investigation was carried out in a water tunnel and in a low speed wind tunnel on a circular, slender cone at high angles of attack (15 deg < alpha < 50 deg) at nominally zero yaw. The potential was explored of a fin, placed between the lee side vortices, to reduce or suppress the asymmetry of the vortex flow, present at high incidences and associated with, in general, undesirable side forces. To this end, flow visualization tests were performed in the water tunnel at a low Reynolds number, Re D &#61 7,800 (formed with the cone base diameter), and in the wind tunnel at Re D &#61 68,100. This qualitative study was supplemented by pressure measurements on the circumference of the cone at four axial sections at Re D &#61 142,000 in order to get some insight into the flow asymmetry and its suppression. Pressures were integrated to obtain sectional side and normal forces acting on the cone, without and with fin. It was found that the application of the fin largely reduced vortex flow asymmetry and the associated side force on the cone. Further investigations, with respect to practical applications, are suggested.