Vortex generator effects on dynamic stall of thick airfoils

This study examined the effect of vortex generators on the dynamic stall characteristics of thick wind turbine airfoils with a relative thickness of 35% and trailing edge thickness of 10% and 2%. The experiments were conducted in the TU Delft LTT wind tunnel at a Reynolds number of Re=1×106 and dynamic reduced frequency ranging from 0.032 to 0.096. The study investigated the impact of various factors on the dynamic stall characteristics of the airfoils, including the vortex generator’s chord position, trailing edge gap, roughness, mean angle of attack, and reduced frequency. The study found that vortex generators delay dynamic stall for thick airfoils by stabilizing the flow during the upstroke phase. However, this can increase the maximum lift overshoot, particularly with flatback airfoils, resulting in a higher drop in lift during dynamic stall. This can potentially increase the dynamic loads on a wind turbine blade due to stall-induced vibrations. The study noted a significant difference in dynamic stall behavior between flatback and non-flatback airfoils. Overall, this research provides valuable insights into the dynamic stall and flow physics characteristics of thick wind turbine airfoils using vortex generators, aiding in more accurate rotor blade design.