PIV flow measurements for heat transfer characterization in two-pass square channels with smooth and 90 degrees ribbed walls

Particle image velocimetry (PIV) experiments have been carried out to study the correlation between the high-Reynolds number turbulent flow and wall heat transfer characteristics in a two-pass square channel with a smooth wall and a 90 rib-roughened wall. Detailed averaged velocity distributions and turbulent kinetic energy for both the main and the secondary flows are given for a representative Reynolds number (Re) of 30,000. The PIV measurement results were compared with the heat transfer experimental data of Ekkad and Han [International Journal of Heat Mass Transfer 40 (11) (1997) 2525-2537]. The result shows that the flow impingement is the primary factor for the two-pass square channel heat transfer enhancement rather than the flow turbulence level itself. The characteristics of the secondary flow, for example, vortex's shape, strength, rotating-direction and positions, are closely correlated with the wall heat transfer enhancements for both smooth and ribbed wall two-pass square channels. The rib-induced flow turbulence increases the heat transfer mainly because of the enhanced local flow impingement near the rib. 2002 Elsevier Ltd. All rights reserved.

PIV flow measurements for heat transfer characterization in two-pass square channels with smooth and 90 degrees ribbed walls Academic Article