Fariba Ajalli - PhD student - Aerospace Research Institute, Aerospace Research Institute
Mahmoud Mani - Profesur, Center of Excellence in Computational Aerospace Engineering-Department of Aerospace Engineering, Amirkabir University of Technology
Mohammad Reza Soltani - Profesor - Department of Aerospace Engineering, Sharif University of Technology

Details of pressure distribution and aerodynamic coefficients on a two dimensional plunging airfoil are presented. Dynamic motion was produced by plunging the model over a range of reduced frequencies beyond its static stall angle of attack . The Reynolds number in the present test was held fixed , and the reduced frequency was varied in wide range. During the oscillating motion, surface static pressure distribution was measured on the upper and lower side of the model. The hysteresis loops of pressure coefficient showed that the reduced frequency had important effects on the unsteady behaviors of the flow. By oscillating airfoil beyond the static stall angle an energetic vortex structure near the airfoil leading edge was formed. The dynamic vortex allowed the airfoil to achieve much higher pressure coefficients before significant separation occurred.

Unsteady Aerodynamic, Plunging Airfoil, Dynamic Stall, Hysteresis loops