Analysis of energy transfers of a sheared flow generated by wall injection

 We propose in this work to characterize the unsteady behavior of a flow generated by wall injection and encountering an obstacle. This sutdy concerns the prediction of the stability of segmented solid propellant rocket motors. The simulation of such a system is studied in cold flow, which makes it possible to analyze the basic phenomena and the energy transfer mechanisms of the flow. The results obtained allow the identification of the vortex structures by visualization inside a shear layer created at the top of an obstacle. The analysis of the pressure field shows that the dynamic parameters (mass flow rate or flow velocity) generate a phenomenon of selective excitation and of longitudinal acoustic modes amplification, which is accompanied by an energy transfer between modes. Received: 30 October 1997 / Accepted: 8 June 1998