Control of an Oscillatory Rectangular Cavity Jet Flow by Secondary Injection(<Special Issue>Jets, Wakes and Separated Flows)

A method for controlling the position of an oscillatory cavity jet flow is demonstrated. The method involves secondary injection of a lower mass flow control jet into the cross-flow region of the primary jet. The primary jet in this case is a turbulent jet (Re=55000) which when injected into the rectangular cavity with no secondary control, attains a stable oscillation with a characteristic Strouhal number of S_<t,W>=0.013. The injection control method is investigated using a combined experimental and numerical approach with a water model test rig and a 2D and 3D computational fluid dynamics (CFD) model. Based on previous work, a baseline cavity, with a depth to width ratio of H/W=0.16 and entry nozzle submergence of S/W=0.38, is used to study the effect of secondary jet injection parameters on primary jet deflection angle (δ) as a function of momentum ratio (β) and injection position (Y_i). Results have shown primary jet deflection angles (δ) of up to 15°for a momentum ratio (β) of 20% can be achieved for a secondary jet injection position of Y_1/W=0.12.