Numerical Characterisation of Active Drag and Lift Control for a Circular Cylinder in Cross-Flow

Abstract

Synthetic jet actuators have shown promise to control drag and lift for a bluff body in cross-flow. Using unsteady RANS CFD modelling, a significant modification of the drag coefficient for a circular cylinder in cross-flow at = 3900 is achieved by varying the actuation frequency. The variation in actuation frequency corresponds to a range in Stokes number of 2.4 < < 6.4. The trends in drag coefficient modification largely agree with the findings of past publications, achieving a maximum drag reduction at = 4.9 for a fixed jet Reynolds number of the synthetic jet of = 12. A decrease in the adverse pressure gradient near the jet orifice correlated with a momentum increase in the viscous sublayer and stronger vortical structures at the rear of the cylinder. In these same conditions, a decrease in turbulence intensity was observed in the far field wake, which is a relevant finding in the context of wind and tidal turbine arrays.

Special Issue “Active Flow Control Technologies for Energy and Propulsive Systems”

“…In reference [15], a numerical study was performed to investigate the effect of varying synthetic jet actuation frequency on drag and lift coefficients, pressure coefficient and the turbulence intensity in the wake of a circular cylinder in cross-flow.…”

Measurements versus Numerical Simulations for Slotted Synthetic Jet Actuator

“…Experimental analyses have been mainly focused on comparing the SJ flow fields to continuous jets [4,12,13], evaluating the efficiency of the device [14], and demonstrating the effectiveness of the device as a flow control technique [15][16][17]. Hot-Wire Anemometry [4,18], Laser Doppler Velocimetry [19], Particle Image Velocimetry [20,21], and flow visualization techniques [18,22] have been usually employed for this purposes.…”