Deformation and wake of a flexible rotor in water

Abstract In this paper, we study experimentally the fluid-structure interaction of a simplified small-scale rotor operating in water channel. The consists single untwisted rectangular blade and is tested with various pitch angles at different rotation speeds free stream velocities. Flapwise deformations are measured using image processing, flow fields obtained by Particle Image Velocimetry. exhibits extreme downstream upstream bending high negative positive angles, respectively. addition, for unsteady flapwise fluctuations observed, accompanied large-scale recirculation zones. These zones formed shed periodically behind rotor, resembling dynamics Vortex Ring State known helicopters steep descent. induced axial velocity near tip changes direction from to downstream, accordance direction, reaching values that exceed twice free-stream conditions. deformation has strong dependence on speed ratio low more pronounced Reynolds number angles. Results two-bladed also shown compared behaviour observed blade.