Heat Transfer in a Channel under Effects of a Shallow-Angle Jet Impingement and a Rib

Experimental studies are carried out to investigate the heat transfer characteristics involving an impinging jet with a shallow-angle in a crossflow. A rib is applied to control the jet impingement heat transfer Liquid crystal technique is employed to measure the wall temperature and obtain the heat transfer coefficients. In the study, the Reynolds number for the crossflow is 80,000 and the Reynolds number for the jet ranges from 20,000 to 40,000. This gives rise to the jet-to-crossflow velocity ratio varying from 1.4 to 2.8. For all the tested cases, it is found that the presence of rib makes the Nusselt number profiles across the stagnation point change from a classical bell-shaped profile to a plateau-like pattern, indicating the enhanced heat transfer region expands more as the rib is present. In particular the presence of rib has a more pronounced effect on the enhancement of heat transfer at lower velocity ratio (R = 1.4). However, in such case, the local heat transfer in the rib corner region deteriorates. At higher velocity ratio, especially at R = 2.8, the presence of rib makes the heat transfer rate more uniform, but meanwhile, it is found that the impinging jet effect tends to be weake