The Effects of Different Pin-Fin Arrays on Heat Transfer and Pressure Loss in a Narrow Channel

This paper describes a detailed experimental investigation of a narrow rectangular channel based on the double-wall cooling concept that can be applicable to a gas turbine airfoil. The channel has dimensions of 63.5 mm by 12.7 mm, corresponding to an aspect ratio of 5:1. The pin diameter, D, is 12.7 mm, and the ratio of pin-height-to-diameter, H/D is 1. The inter-pin spacing is varies in both spanwise and streamwise directions to form two inline, and two staggered pin-fin configurations. The Reynolds number, based on the hydraulic diameter of the pin fin and the mean bulk velocity, ranges from 6,000 to 15,000. The experiments employ a hybrid technique based on transient liquid crystal imaging to obtain the distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all the pin elements. The heat transfer on both the endwall and pin-fin surfaces revealed similar pattern compared to the typical circular pin-fin array, which were conducted at higher Reynolds number. The total heat transfer enhancement of current pin-fin array is approximately four times higher than that of fully developed smooth channel with low pressure loss, which resulted in much higher thermal performance compared to other pin-fin array as reported in the literature.Copyright © 2015 by ASME