Transient Process of Separation Control on a NACA0015 Airfoil

Abstract

Experiments concerning the control of flow separation were conducted on a NACA0015 airfoil model with a chord length of 0.35 m at a Reynolds number of 1 million. We analyzed the impact of the transient attachment and separation process on the mean and turbulent fields. To control the flow, angled fluidic vortex generators through 44 orifices were positioned in a single array at a position of 30% from the leading edge of the airfoil. PIV measurement was applied to the vicinity of the wake with the airfoil set at an incidence of 11° with a separation length of 1/3 chord from the trailing edge. Optimization was not performed, although the Cd reduced from 0.0275 to 0.02 and the Cl indicated an improvement of ~17%. Phase-averaged energy distributions were performed in the near wake. When the actuators were impulsively deployed, the data showed the trace of the passage of a large eddy associated to the beginning of the attachment process over the airfoil. It had a strong transient effect on the turbulent energy. When the FVGs were deactivated, a gradual increase in the turbulent energy was observed. Detailed analyses of the mean and fluctuating fields were provided.