Experimental study on control of highly unsteady separating flow

An attempt to control an unsteady flow separation from a flat plate surface using a jet ejection is carried out. The unsteady flow is artificially generated by periodically moving a curved ceiling up and down at a constant frequency. The controlling system consists of a jet ejecting device on the upstream side and tufts attached to the surface on the downstream side. The movements of the tufts are monitored by a USB camera to watch for a flow separation. Once a separation is detected, a jet is ejected into the boundary layer through a slot in the plate. The jet ejection causes the separation region to shift downstream and become smaller. In addition, it is revealed that the control effect can be enhanced by stirring the fluid, generating turbulence, before it is ejected into the boundary layer.