Transition Prediction for Hypersonic Conical Flows with Active Cooling

Kurzfassung

The purpose of this research is to identify the influence of effusion mass fluxes and various nose radii on the boundary layer instability for a hypersonic flow and predict the transition location. The laminar-turbulent boundary layer transition for hypersonic vehicles is of great importance, because it can significantly increase the frictional resistance and the heat transfer coefficients. Effusion cooling uses various mass flows blown out through a porous ceramic for cooling the surface. This type of cooling is also called effusion. The investigations were carried out for Ma = 10 hypersonic flow past a 7° half angle blunted. The numerical stability analysis is performed with the DLR Code NOLOT which solves the equations of the linear stability theory. The critical N-factors are assessed by means of previous experiments at the HEG wind tunnel in Göttingen. Growth rates and N-factors for different nose radii and various effusion mass fluxes were calculated, and consequently the transition locations were determined.