Transient Process of Separation Control on a NACA0015 Airfoil
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.
KeywordsUnsteady separation control NACA 0015 airfoil Fludic Vortex Generator Transient phenomena Unsteady wake Turbulent fluctuations Turbulent shear stress PIV Hot Wire
The authors gratefully acknowledge Dr. J. Tensi for the wind tunnel tests and the financial support for FP7/2010-2013, MARS programme.
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