An Investigation of the Fundamental Cause of Asymmetric Separated Flow

Abstract

Abstract : The cause of the phenomenon of steady asymmetric flow on cones at moderately high angles of attack is the subject of this investigation. At very higher angles of attack, the flow will become unsteady with a Karman vortex street being shed downstream. This second phenomenon was not considered in the current research project. The investigation used computational fluid dynamics as a tool to uncover the fundamental cause of asymmetric separated flows. The appearance of new flow features as the critical angle of attack was approached was studied in detail. Isolating asymmetric disturbances to specific portions of the flow was also attempted. The stability of the symmetric flow above the critical angle of attack was investigated analytically. The transition of the flow from symmetric to asymmetric as the computation was continued was studied in detail. All of these studies indicated that the interaction of the vortices in the cross flow plane results in an instability in the symmetric flow. In addition, the interaction between the vortices seems to be somewhat global in nature.