Steady Aerodynamics of Miniature Trailing-Edge Devices in Transonic Flows

Abstract

The steady aerodynamic effect of miniature trailing-edge devices on a supercritical airfoil was investigated in transonic flow both experimentally and numerically. The investigations were performed for the Gurney flap, the split flap, and the divergent trailing edge, and they showed a strong influence on the supersonic flow regime, influencing the lift and drag characteristics. At constant lift, a redistribution of the lift generation from the front to the rear part of the airfoil takes place. Total-drag reductions can be achieved by the reduction of wave drag. The influences of the different types of miniature trailing-edge devices are shown. The investigation of the influence of geometry parameters showed that the variation of the height of the Gurney flap and of the deflection angle of the split flap have similar effects. Perforation of the miniature trailing-edge devices showed only a small influence. The investigation of the influence of the freestream parameters indicated that increases in Mach number and Reynolds number increase the miniature trailing-edge device effect. A drag-optimal application is possible with adaptive miniature trailing-edge devices, and the same performance is achieved by an adaptive Gurney flap and an adaptive split flap. A comparison with a flexible trailing edge could identify performance advantages of the miniature trailing-edge devices.