Cooling methods are needed for gas turbine blade tips that are exposed to high temperature gas. A common way to cool the blade and its tip is to design serpentine passages with 180-deg turn under the blade tip-cap inside the turbine blade. Improved internal convective cooling is therefore required to increase the blade tip lifetime. This paper presents numerical predictions of turbulent heat transfer through two-pass channels with and without guide ribs (guide vanes) placed in the turn regions using RANS turbulence modeling. The effects of adding guide ribs on the tip-wall heat transfer enhancement and the channel pressure drop have been analyzed. The inlet Reynolds numbers are ranging from 100,000 to 600,000, and the rib cross-section blockage ratio (rib height to channel height, 2e/H) is 0.182. The detailed fluid flow and heat transfer over the tip-wall are presented. The overall performances of three two-pass channels are evaluated and compared. It is found that the tip heat transfer coefficients of the channels with guide ribs are 20%∼50% higher than that of a channel without guide ribs. The presence of guide ribs could lead to an increased (about 15%) or decreased (up to about 12%) pressure drop, depending upon the geometry and placement of guide ribs. It is suggested that the usage of guide ribs is a suitable way to improve the flow structure and augment the blade tip heat transfer, but is not the most effective way to augment tip-wall heat transfer compared to the augmentation by surface modifications imposed on the tip directly.
Analysis of Enhanced Heat Transfer on a Turbine Blade Tip-Wall With and Without Guide Ribs
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Xie, G, Sunde´n, B, Zhang, W, Utriainen, E, & Wang, L. "Analysis of Enhanced Heat Transfer on a Turbine Blade Tip-Wall With and Without Guide Ribs." Proceedings of the ASME 2010 International Mechanical Engineering Congress and Exposition. Volume 7: Fluid Flow, Heat Transfer and Thermal Systems, Parts A and B. Vancouver, British Columbia, Canada. November 12–18, 2010. pp. 1387-1394. ASME. https://doi.org/10.1115/IMECE2010-37302
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