Behaviour of hypersonic wind tunnels diffusers at low Reynolds numbers

This paper deals with the behaviour of hypersonic wind tunnels diffusers at low Reynolds numbers The phenomena that occur in the diffusers at relative ly low Reynolds numbers are particularly critical due to the interactions b etween shock waves and the large boundary layers present in the long throat , which can reduce the maximum recovery pressure and therefore the efficien cy of the diffuser. The aim of the present paper is to correlate the result s obtained by numerical simulations of the diffusers with the experimental results, obtained using a high enthalpy blow down are jet facility. The num erical and experimental results are in agreement and show that, for the ran ge of Reynolds number investigated, the diffuser efficiency is smaller comp ared to the values determined for similar diffusers operating at larger Rey nolds numbers. (C) Elsevier, Paris.