Wind-tunnel investigations of wings with serrated sharp trailing edges.

Abstract

Exploratory wind tunnel force measurements are presented for two wing geometries with small scale planar and nonplanar serrated trailing edge devices (chord Reynolds numbers ranged from 1.0-3.7x106). The planar serrated trailing edge extensions reduced the drag at conditions when trailing edge separation occurred at low angles of attack. The introduction of serrations reduced or eliminated the drag penalty due to the small (1 to 2 per cent of the chord length) nonplanar trailing edge flaps, while maintaining the effects of increase in camber. The presence of streamwise vortices immediately downstream of the serrated trailing edges is believed to have favourably affected the boundary layer flow approaching the trailing edge and the near wake development, resulting in reduced pressure (form) drag. (A)