Spanwise Directed Synthetic Jets for Wall Turbulence Control

Abstract

This investigation focuses on the effects produced by the forcing of adjacent synthetic jets arrays injected tangentially to the wall in the spanwise direction of a fully developed turbulent channel flow. The effects of the forcing frequency and of the synthetic jets arrays configuration are investigated. Instantaneous wall shear stress and streamwise velocity fluctuations give evidence of drag reduction and also turbulence attenuation up to 20%. The benefits of the forcing are remarkable along the channel axis up to 153 half channel height and are persistent in the spanwise direction up to a quarter of channel width. The forcing frequencies producing drag reduction and turbulence attenuation are of the order of few Hertz at the Reynolds number investigated (Re_tau=180)