NUMERICAL INVESTIGATION OF DESIGN AND OFF-DESIGN OPERATION OF SUPERSONIC MIXED-COMPRESSION INTAKES

The design and off-design operation of a mixed-compression supersonic intake is studied using two-dimensional Euler equations. Unstructured cell-vertex, finite volume, upwind scheme based on Roe's approximate Riemann solver is used to solve the governing equations. The intake experimentally studied by Anderson and Wong [1-3] is used as a model for supersonic intakes. The effect of the engine back pressure on the performance of the supersonic intake is investigated. For supercritical operation, as the back pressure increases, the pressure recovery increases due to the decrease in the terminal normal shock wave strength as it travels towards the throat. For subcritical conditions, the shock wave travels through the geometric throat to the convergent portion of the intake, where the shock position is unstable and the intake is 'unstarted'. Optimum throat area and cowl translation schedules are predicted to keep intake started at off-design operation. This ensures full flow ratio and hence no spillage.