Experiments on a Supersonic Parallel Diffuser

Abstract

This paper reports the results of experimental work on a two-dimensional model of a supersonic parallel diffuser of the type used to achieve some recompression of a high-temperature jet, though in the present tests a relatively low temperature was employed. Visual observations were made of the flow patterns developed in the diffuser, together with corresponding measurements of static pressure distributions and local heat transfer rates, for a range of initial total pressures. The effect of varying the area of the diffuser cross-section, for the same upstream generating nozzle, has also been studied. The static pressure recovery across the diffuser is found to reach a maximum at the transition from a normal shock to a multiple oblique shock system of diffusion. Following a peak value near the diffuser entry, the heat transfer, which generally follows the static pressure distribution, fluctuates about relatively low values in the region of the shock patterns, but rises steadily when the flow becomes subsonic in the downstream section of the duct.