NUMERICAL SIMULATION OF GROWING DISTURBANCES IN A THREE DIMENSIONAL HYPERSONIC COMPRESSION RAMP

摘要

Numerical predictions in laminar compression ramps (body/body-flaps configurations) usually require the inclusion of three dimensional effects to correlate separation lengths with experimental measurements. Also, in the presence of large recirculation regions, the heat transfer calculated over the compression ramp underestimates the experimental values. The discrepancy could be due to turbulent transition in the separation process, where flow perturbations may play a major role in heat transfer distribution. In the present work numerical simulations were carried out over 3D 25° compression ramps in a laminar hypersonic flow at Mach 6.85 and a Reynolds number per unit length of 2.45 x 10~6m~(-1). Two configurations have been studied, one allowing lateral spillage of the flow and the second with lateral side plates following the same model as experimental works, held in the University of Southampton. To obtain the steady solution, a three dimensional implicit Godunov scheme with the HLLC approximate Riemann Solver is used. A spanwise periodic velocity perturbation is imposed in the flat plate ahead separation. The scheme reverts to explicit to compute the unsteady solutions.