Numerical study of large amplitude, nonsinusoidal motion and camber effects on pitching airfoil propulsion

The effects of large amplitude and nonsinusoidal motion on pitching airfoil aerodynamics for thrust generation were numerically studied with a 2-D NACA0012 airfoil used, and various 2-D NACA asymmetric airfoils were applied for camber effect study. The large amplitude effect study has been undertaken over a wide range of reduced frequency k (from 6 to 18) and pitching amplitude θ (from 5° to 30°) at Re=1.35×104 with sinusoidal pitching profile used. It is shown that the large pitching amplitude results in much more thrust generated than that at low pitching amplitude and the increase of thrust with amplitude becomes slow when the amplitude reaches some degree. However, the propulsive efficiency noticeably decreases with the increase of θ at a fixed k.