An experimental study of turbulent flow behind a delta winglet

Abstract

The vortical turbulent flow generated by a 10mm high and 20mm long delta winglet on a flat surface was experimentally studied in a wind tunnel. The flow field at 10 winglet heights downstream was measured using a triple wire probe at a Reynolds number of 5000, based on winglet height. Main vortex and induced vortex structures were observed in the form of the cross-stream velocity vector and the vorticity contour. Boundary layer thickness, streamwise velocity distribution, turbulence intensity and Taylor microscale were compared at the inflow and outflow regions as well as in the base flat plate case. The inflow region was postulated to have a larger potential for heat convection; since the vortex penetrated into the boundary layer, the boundary layer thickness increased, while maintaining high turbulence intensity. At the core of both the main vortex and the induced vortex, both the streamwise velocity deficit and the turbulent intensity were enhanced.