Experimental Investigation of Shock-Wave/Boundary- Layer Interactions Over an Artificially Heated Model in Hypersonic Flow

Experimental tests have been carried out to analyze the effect of wall-to-total temperature ratio on the characteristics of a fully laminar shock-wave/boundary-layer interaction in a Mach 6 high enthalpy flow. Test cases were run in a new high-enthalpy arc-heated wind tunnel developed at Centrospazio in the framework of the ESA/FESTIP program. In order to heat-up the model surface a high temperature radiator movable on a remotely controlled displacement system was employed. As the investigation was focused on local dynamic and thermal loads, the model was instrumented with pressure transducers and thin film gauges. The experimental results were compared with numerical simulations carried out at CIRA on the same test cases. Pressure measurements showed a fair agreement with numerics, even if the accuracy of the measurements did not allow to discriminate the differences within the different wall temperature cases numerically calculated. Heat flux data are consistently higher than what calculated by CIRA: further investigation is presently under way to identify the reason of this difference, however the main reason is believed to be related to relaxation phenomena of the frozen flow on the model surface. Additional investigation aimed at evaluating the importance of this effect are presently underway. Introduction The development of hypersonic vehicles has renewed the attention on the problem of viscous-inviscid flow interactions and, in particular, on shock-wave/boundary-layer interaction (SWBLI) phenomena that are of great practical importance for air-breathing engine inlets, wing/body junctures and deflected control surfaces. The SWBLI was identified as one of the critical points to be analyzed in the framework of European Space Agency FESTIP-Future European Space Transportation Investigation Programme. Prediction of thermal and dynamic loads on surfaces exposed to hypersonic flows is an essential prerequisite for the effective design of aerodynamic control surfaces and thermal protection system of modern space vehicles, as concerns their trans-atmospheric flight portion. In this context, the interaction of shock waves with boundary layers on surfaces at relatively high temperatures is an important aspect of high speed fluid dynamics because of its frequent occurrence in applications and its impact on the behavior of the boundary layer. In particular, with respect to fully laminar interactions, the extension of the resulting separation bubble is of prime importance cause pressure and heat transfer reach a maximum in the reattachment region. Theoretical prediction of shock wave-boundary layer interactions by purely analytical means is limited by the complexity of the physical phenomena involved, which is especially …