Experimental measurements were taken in a closed, recirculating, turbulent separ¬ated flaw. The recirculating flow was generated by a conical baffle placed on the axis of a circular duct and was closed by reducing the duct diameter at a distance downstream of the baffle.nMass exchange data was obtained by injecting a tracer gas at various positions within the recirculating /low and then taking detailed concentration measurements throughout the flow field. The mass transport along the mixing layer is shown to haw a similar variation to the momentum transport.nOverall features of the exchange processes are shown to be similar to simple two-dimensional, non-ducted mixing flows if allowance is made for the three dimensionality of the present layers. However it is also shown that there are significant quantitative differences between the two flows. Reasons for these differences are advanced.nThe overall mass exchange rate between the two flow regions was found to be one-third of the mass rate supplied to the combustor and this is a typical figure for conventional designs. Methods of increasing this exchange rate are discussed.
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