Experimental investigation on active control of flow around a finite-length square cylinder using dual synthetic jet

Abstract

This paper presents an active flow control method for flow around a finite-length square cylinder using dual synthetic jet (DSJ). A piezoelectric dual synthetic jet actuator (DSJA) was installed at the leading edge of the free end for generating the DSJ. The amplitude and frequency of DSJ can be adjusted through the driving voltage and driving frequency. In our research, the pressure measurements and flow visualization are conducted to test the control effectiveness of dual synthetic jet. According to the aerodynamic results, there is a correlation between the control efficiency and the amplitude and frequency of DSJ, which are determined by jet momentum coefficient and driving frequency. After the application of the free-end DSJ with moderate amplitude and frequency, the maximum reduction of total mean drag coefficients, fluctuating drag coefficients and fluctuating lift coefficients respectively reached 4.3%, 18.0% and 30.8%. Moreover, the smoke-wire and PIV results indicate that there is a remarkable suppression of the free-end separated shear flow and a prominent increase in the TKE in the area near the free end. All results point to that the aerodynamic forces and wakes of a surface-mounted finite-length square cylinder can be effectively controlled using dual synthetic jet at free end.