Analysis of unstable shock waves in turbulent flows using entropy controlled instability (ECI) method

Unstable combustion wave instabilities in turbulent flows are investigated using the entropy controlled instability (ECI) method. In this method, the nonlinear stability equation is derived from the entropy-controlled acoustic energy equation with the space and time averaged integrals as calculated from the Navier-Stokes solutions. The advantage of the present technique is its capability of dealing with combined effects of shock waves and turbulent motions. The state of stability or instability is then determined by solving the nonlinear stability equation which represents the flowfield calculated from the Navier-Stokes solver. Two-dimensional axisymmetric cylindrical geometries as applied to the Space Shuttle main engine thrust chambers are analyzed and the results are compared with those for laminar flows.