  The present study aims to investigate the effectiveness of plasma actuators
in controlling the flow around a finite wall-mounted square cylinder (FWMSC)
with a longitudinal aspect ratio of 4. The test is conducted in a small-scale
closed return-type wind tunnel. The Reynolds number (${Re}_d$) of the
experiments is 500 based on the width of the bluff body and the freestream
velocity. The plasma actuators are installed on the top surface and the rear
surface of the square cylinder. The induced flow velocities of the plasma
actuators are modulated by adjusting the operating voltage and frequency of the
high-voltage generator. In this work, particle image velocimetry (PIV) is used
to obtain the velocity fields. Furthermore, force measurements are conducted to
investigate the effect of using plasma actuators with different driving
voltages on the drag force. Our results show that the plasma actuators can
successfully suppress flow separation and reduce the size of the recirculation
region and turbulent kinetic energy (TKE) in the wake. A correlation between
the drag coefficient and the operating voltage of the power generator is also
revealed and the mean drag coefficient is found to decrease with increasing
imposing voltage. The plasma actuators can enhance the momentum exchange and
the interactive behavior between the shear layer and the flow separation
region, resulting in flow reattachment at the free end and shrinkage of the
recirculation zone in the near-wake region of the bluff body. Overall, the
present study demonstrates the practical effectiveness of using plasma
actuators for active flow control around FWMSC.
