The Study of Reynolds Number Effect on the Behaviors of Asymmetric Vortices Flow

Abstract

In order to study the Reynolds number effects on the behaviors of asymmetric vortex flow over slender body the experimental investigations were carried out in D-4 Low Speed Wind Tunnel of BUAA with pointed tangent ogive/cylinder model with the angle of attack 50° at Reynolds numbers 0.1×l06~1.0×l06. A new transitional separation pattern in the inception regime was found at the Reynolds number 0.2×l06, which means the laminar boundary layer separation with the turbulent shear layer reattachment on one side and the laminar boundary layer separation without reattachment is still kept on the other side. And the pressure difference ΔCp = Cpsep - Cpmin can be selected as criterion to determine the lower-critical and upper-critical Reynolds numbers for inception regime quantitatively. In the post-critical regime it is found from the present study that the asymmetric vortices behaviors are no longer changed with Reynolds numbers. Moreover, the asymmetric vortices flow pattern at bistable state will switch over two cycle. And a close correlation between circumferential position of manual micro-perturbation block and the response of asymmetric vortices flow pattern is revealed over the post-critical Reynolds number region.