Synthetic Jet Control Effectiveness on Stationary and Pitching Airfoils

Abstract

A computational study has been conducted to investigate the control effectiveness of a synthetic jet on a stationary and a pitching NACA 0015 airfoil at a Reynolds number of 360,000 based on the chord length. For the stationary airfoil, the optimum location of the synthetic jet was at 28% of the chord length. The nondimensional maximum forcing amplitude was 0.75 and the nondimensional forcing frequency was 18.67. The increase in lift was more pronounced at higher incidences, whereas the effectiveness of the synthetic jet reduced at lower incidences. Imparting movement of flow far away from separation point was useful for lift enhancement. The location of the jet close to separation point was suitable for drag reduction. The pitching airfoil was driven in a periodic cycle corresponding to α = 5 + 10 sin(0.15t). A synthetic jet with nondimensional maximum forcing amplitudes of 0.75 and 1.88, and nondimensional forcing frequencies of 18.67 and 31.13 was employed. The higher frequency was suitable for lift enhancement whereas the higher amplitude was suitable for drag reduction. A single synthetic jet was not able to suppress the vortex formation and shedding; however, the overall airfoil performance was enhanced. The k-w shear-stress transport model successfully predicted the flow events of both airfoil configurations.