Heat Transfer on Convective Surfaces With Pin-Fins Mounted in Inclined Angles

Abstract

Casting of pin fins at the trailing edge of the turbine blades often presents some difficulties due to tight dimensional tolerances, leaving the pin fins inclined after the casting process. This study is to experimentally examine the effects of such an imperfect manufacturing phenomena on the heat transfer and friction characteristics over pin-fin arrays with different pin inclinations. The test model is a staggered short (H/D = 1) pin-fin array with an inter-pin spacing of 2.5 times the pin-diameter (S/D = 2.5) in both longitudinal and transverse directions. Detailed local heat transfer coefficients on both array endwalls and pin elements are determined using the transient liquid crystal technique, as the inclined angle θ varies from 40° to 90° and the Reynolds number ranges from 7.0 × 103 and 1.3 × 104. The measured data suggest that an increase in pin inclined angle relative to its normal orientation (90-degree) significantly reduces the level of heat transfer enhancement from the array. Such a reduction amounts to nearly 50% for the 40-degree case. The accompanied friction loss also decreases.