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

Abstract

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 weaker.

Heat Transfer Augmentation Technologies for Internal Cooling of Turbine Components of Gas Turbine Engines

“…Another recent investigation focuses on internal and external cooling methods in combination, by addressing the interactions between internal ribs and external coolant film [171]. The combination and interaction of internal ribs with impingement and/or effusion cooling is described by Yang et al [164] and Wang et al [172]. Utilizing pin fins and dimpled surfaces together is illustrated by the results which are given in Figures 12 and 13 from Rao et al [5].…”

“…In regard to these more recent studies, data from pin fin investigations [9,140] are designated with red symbols, data from rib investigations [6,[154][155][156] are designated with blue symbols, data from one mesh cooling study [176] are designated with green symbols, and data from investigations which employ dimples and protrusions [4,10,142] are designated with brown symbols. Note that some of the combination device results from the previous section [5,11,136,164,[168][169][170][171][172] are not included since friction factor ratio data are not available in these studies. The mesh cooling arrangement, employed by Bunker et al [176], employs a "small diamond with dimpulators" arrangement.…”