Wake Structure of Heaving Elastic Airfoils and Their Dynamic Thrust

An unsteady flow in a low Reynolds number region attracts attention in recent years. The authors measured vortex flow in the wake of the rigid flat plate, rigid NACA0010, elastic flat plate and elastic NACA0010 with heaving motions and evaluated accelerating flows induced by the vortex flow patterns and vortex flows in the wake of the airfoils. Furthermore, we measured dynamic thrusts acting on these airfoils with heaving motions and clarified their relations with vortex flows. The clear thrust producing vortex street is formed in the wake of the elastic airfoils even at a comparatively low Strouhal number. The clear accelerating flow is formed in the wake of the elastic airfoils. The dynamic thrusts that act on the rigid NACA0010, elastic flat plate and elastic NACA0010 are strongly dependent on the Strouhal number based on the trailing edge amplitude regardless of heaving amplitudes, heaving frequencies, airfoil shapes and elastic deformations.