Raezeh Rasi Marzabadi - Assistant Professor, Astronautics Research Institute, Iranian Space Research Center
Mohammad Reza Soltani - Professor, Sharif University of Technology

A series of experiments were carried out to study unsteady behavior of the flow field aswell as the boundary layer of an airfoil oscillating in plunging motion in a subsonic windtunnel. The measurements involved surface pressure distribution complimented with surfacemountedhot-films. The effect of leading-edge roughness that simulates surface irregularitieson the wind turbine blades was also studied on variations of aerodynamic loads andboundary layer behavior. The results show that variations of the surface pressure coefficientsand aerodynamic loads with the equivalent angle of attack showed strong sensitivity toreduced frequency and mean angles of attack. Furthermore, boundary layer transitionoccurred earlier for increasing rather than for decreasing the effective angle of attack.

Boundary layer transition, plunging, reduced frequency, wind turbine