An Experimental Investigation of Roll and Yaw Coupled Oscillations of a Delta Wing

Abstract

An experimental investigation was undertaken to study roll and yaw coupled oscillation of a delta wing. Results indicated that the oscillations started at a mean α = 29 for all cases. Beyond which the amplitude of oscillations amplified indicating that the axial stability of the vortex propagates upstream at which point the wing oscillations peak. The existence of an onset of oscillation angle was found. Consequently, a self sustaining limit cycle was observed for roll - free, yaw - free and the all - free test case. A sinusoidal oscillation in CL was observed for all cases as well as a linear increase in mean CL with increasing angle of attack. The coupling effect of roll and yaw exhibited an attenuation of the amplitude of roll and yaw oscillation. Canard and double delta wing configurations were tested as passive flow control devices to dampen wing roll and side slip. These configurations not only effectively decreased both roll and yaw oscillations, a large increase in the CL was also observed. For both the canard and the double delta wing configurations the wing roll oscillation decreased significantly and side slip disappeared all together. A delay in stall and an increase in CD were also noted.