Abstract:
It has been clarified in a recent wind tunnel test that the wingtip vortices generated from the leading edges of the pair of fins which is opening along the flow direction begin to interfere each other, and further make the formation of the asymmetric flow in transonic speed as the angle of pitch increases to some extent. The asymmetric flow generates large side force and rolling moment, and brings difficulties to the controllability of the fins. It is necessary to study the way to eliminate the asymmetric flow. This paper presents the changes of the asymmetric flow versus angles of pitch, and investigates the mechanism of the formation of the asymmetric flow based on numerical method. And then two ways to eliminate the asymmetric flow are proposed. The results show that as the angle of pitch is large enough, the interference of the asymmetry of the vortices becomes stronger generally till one of the vortices disappears. It is effective to eliminate the asymmetric flow, either through reducing the root chord length or cutting off the local area around the leading edge, and in the meantime the effectiveness of the fins is close with that of the base fin which has stable wingtip vortex formation.