Effects of Forced Asymmetric Transition on Vortex Asymmetry Around Slender Bodies

摘要

A wind-tunnel experiment was conducted to study the effects of forced asymmetric transition on the asymmetric vortex system of a slender body by adding a grit strip on either side of the body. The results showed that the effect is very different depending on whether transition of the boundary layer occurs first on the higher vortex side or on the lower vortex side. If the transition first occurs on the higher vortex side, the transition will strongly influence the asymmetric vortex behavior and the side forces induced. The asymmetric vortex system will abruptly reverse its orientation when transition occurs and then gradually recover to its original position with increasing Reynolds number. However, if the transition first occurs on the lower vortex side, the trend of the asymmetric vortex system with increasing Reynolds number will be very similar to the case of natural transition. In addition, the asymmetric transition of the boundary layers on the forebody seems to have a dominant effect on the behavior of the asymmetric vortex system. The associated separation angles of the boundary layers appear to play a pronounced role in the development of the asymmetric vortex system.