Mean velocity development in the asymmetric near wake behind a GAW(2) airfoil

ABSTRACT The two-dimensional turbulent asymmetric near wake behind a General Aviation Wing-2 cambered airfoil section is studied at a subsonic speed at zero angle of attack. The near wake flow, which is dictated by the interaction of the on-coming turbulent boundary layers, development has been discussed in this paper. The pressure coefficient distribution on the cambered airfoil has been measured. Mean velocity profile measurements were made in the turbulent near wake flow behind the airfoil. Minimum mean velocity, wake half thickness, momentum thickness and shape parameter based on the streamwise component of mean velocity development in the turbulent near wake are presented here. It is shown that the mean velocity profile which is asymmetric initially near the trailing edge tended to become symmetric as the distance behind the trailing edge was increased. Mean velocity development was seen to display symmetry at a distance of around 60 trailing edge momentum thicknesses from the trailing edge of the model. The focus on near wake flow behaviour with mean velocity profile asymmetry, is motivated by their importance of the high-lift systems utilized in the commercial transport airplane designs. For the asymmetric wake, streamwise evolution of mean velocity are documented in detail. In this manner, the development of wake flow from the initial asymmetry behind the airfoil is isolated. Keywords: Near wake, GAW(2) airfoil, pressure coefficient, mean velocity, momentum thickness, drag coefficient.