Computational analysis of base flow jet plume interaction

Computations of the flow around a blunted cone-cylinder rocket model with a centrally protruding nozzle are presented. The computations are performed for supersonic free streams of Mach 2 and 3, while the jet exhausting from the nozzle had an exit Mach number of 4 and operated at various jet stagnation pressures, such as to have different jet exit pressure to ambient flow pressure ratios. These ratios all exceeded unity indicating that one had to do with under-expanded jetflow. The present investigation was part of a joint computational/experimental research program on base flows of rocket propelled vehicles. Computational results of two codes based on the Reynolds Averaged Navier-Stokes equations are presented, a finite-volume code using 1D upwind schemes and structured multi-block grids, and a multi-dimensional upwind method on unstructured grids. Different turbulence models have been used. Computed results for several conditions are compared against each other and experimental data. The results show good agreement in those parts of the flow which are not dominated by viscous effects. The prediction of the base flow, however, is the most difficult problem.