Turbulent Flow and Heat Transfer in a Symmetric Expansion Plane Channel

Experimental results of turbulent flow and heat transfer in the separated and reattached flow in a symmetric expansion plane channel are presented. Experiments were conducted using a low speed open circuit wind tunnel, the expansion ratio of channel was 2.0 and the Reynolds number 15000, respectively. The flow and temperature fields were measured using split film probes and a cold wire. The conditional sampling techniques were employed in order to investigate the large scale vortex structure shed from the reattachment flow region and its correlation with the heat transfer behavior. It is found that the local Nusselt number profile is considerably different on the upper and lower walls due to the Coanda effect. Two large scale vortices shed from the reattachment regions on two walls are combined into one large vortex in the redeveloping region, whose configuration is estimated to be an ellipse inclined to the main flow.