Heat Transfer and Frictions in the Convergent/divergent Channel with Lambda/V-shaped Ribs on Two Walls

Abstract

The local heat transfer and total pressure drops of developed turbulent flows in the ribbed rectangular convergent/divergent channels with Lambda/V-shaped ribs have been investigated experimentally. The channels have the exit hydraulic diameter (Dho) to inlet hydraulic diameter (D-ht) ratios of 0.67 for convergence and 1.49 for divergence, respectively. The Lambda/V-shaped ribs with three different flow attack angles of 30 degrees, 45 degrees, and 60 degrees are manufactured with a fixed rib height (e) of 10 mm and the ratio of rib spacing (S) to height (e) of 10 on the walls. Thermal performances of the ribbed rectangular convergent/divergent channels are compared with the smooth straight tube under identical pumping power. The results show that the flow attack angle of 45 degrees with.-shaped rib has the greatest thermal performance at all the Reynolds numbers studied in the convergent channel; whereas, the flow attack angle of 60 degrees with V-shaped rib has the greatest thermal performance over Reynolds number of 30,000 in the divergent channel.