An experimental investigation of transition point over a quasi-2D swept wing by using hot film

Abstract

In this study, we performed experiments to investigate the effect of sweep angle on the transition location of laminar flow to turbulent flow. Three half wing models were used, each having a different sweep angle but with the same aspect ratio in various angles of attack. Two flat plates were used at the ends of the swept wing models to prevent the flow from rolling up over the wing. By simulating flow over infinity swept wing by eliminating tip vertices, the effect of sweep angle on flow transition phenomenon was investigated. The experiments included the study of transition flow via hot-film sensors, which were glued on the wing surface. We found that the small leading-edge radius and low Reynolds number used in the experiments showed the effect of cross-flow mode is dominant over flow transition, rather than other flow instability modes on the leading edge of the wing. Increasing the swept angle therefore leads to enforcement of cross-flow mode and, in return, causes rapidity of flow transition. The increasing angle of attack makes the location of transition nearer to the leading edge.