Basic Study on the Heat Transfer Augmentation in a Recirculating Flow Region

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Experimental and numerical studies were performed to see if it possible to enhance the heat transfer in the downstream region of a backward-facing step, where heat transfer is normally deteriorated, by the insertion of cylindrical body near the top corner of the step.From the results of the heat transfer experiment flow visualization and measurement of the averaged and fluctuating flow fields by LDV for the case when a cylinder was inserted, the following conclusions were obtained ;1) When the cylinder was mounted at a proper position, a jet-like flow pattern emerged in the averaged velocity profile beneath the cylinder, and the recirculating flow was intensified.2) The velocity fluctuation was intensified in the near wall region resulting in the effective augmentation of heat transfer.3) These intensifications result the enhancement of deteriorated heat transfer in the recirculating flow region.From the results of the numerical computation made for the backward-facing step flow obstructed by a square rod, it was concluded that the recirculating flow region can be destabilized when a square rod is properly mounted near the step, and that it causes the augmentation of heat transfer.