21403 Effect of Leading Edge Shape of 3-Dimensional Airfoil on Dynamic Lift

Unsteady fluid forces acting on a three dimensional model in the sinusoidal pitching motions under conditions of several frequencies were measured by using the ring structure 2 elements balance. Dynamic lift/drag coefficients were compared to the steady ones. In this study, in order to investigate the effect of leading edge profile on unsteady fluid forces, two types of model were installed: a discoid airfoil (Model-CN) and a triangular wing-shape (Model-TR). The delay of stall for Model-CN is observed and also the value of maximum lift coefficient is greater than the maximum lift coefficient under stationary condition. On the other hand, dynamic lift/drag coefficient profiles for Model-TR show same tendency to the dynamic lift/drag coefficient profiles under stationary condition. The unsteady fluid forces are affected by the leading edge profile.