Trailing-Edge Flap Control of Dynamic Pitching Moment

Abstract

The effects of upward ramp rate, actuation start time, and duration of a moveable trailing-edge flap on the critical aerodynamic values of an oscillating wing were investigated. The largest improvement in the peak negative pitching moment was obtained with a fast ramp rate and a start time near the mean angle. The largest value of net work coefficient, however, was generated with a delayed start time and a slower ramp rate. The peak lift coefficient decreased with increasing ramp rate and decreasing start time. The inclusion of a short steady-state portion in the flap motion was beneficial. An upward flap deflection initiated slightly after the mean angle during pitch-up, moved to its maximum deflection at a moderate speed, remained steady for a rather short period, and then returned to its initial position, which spanned half the oscillation cycle, was found to provide a best compromise between the various aerodynamic requirements.