Improved Approach to an Endwall Heat Transfer Analysis: A Linear Guide Vane and a Curved Duct

This paper consists of two sections. The first section of the paper illustrates successful application of the improved approach developed by author to the endwall heat transfer data analysis in a low speed linear guide vane and in a curved duct. Effects of a three dimensional turbulent flow, a horseshoe vortex, a passage vortex, as well as an entry boundary layer thickness have been considered in both passages and as a result the common experimental correlation on a local heat transfer have been derived for the H/t = 1.0 ratio. All affected factors are presented as a superposition of the linear correction functions in the basic experimental correlation for a flat plate heat transfer. In the second section the common correlation is used as the reference correlation to establish effect of the span-to-pitch ratio on the endwall heat transfer in both passages. It was found that variation in the H/t ratio affects slightly the freestream velocity; the most important result which came from the heat transfer study is that in contrast to a curved duct a heat transfer rate in a blade passage is reduced while the H/t ratio decreases. Comparison of the experimental data obtained by the author with results of the two-dimensional heat transfer prediction confirms that it is very important to take a three-dimensional heat transfer nature into account in design of the endwall convective cooling system. It has been demonstrated that distinction between the results of two- and three dimensional approach to the endwall heat transfer can achieve up to 70% at the passage’s inlet area.