Abstract

The cooling of the turbine blade plays a vital role in increasing the durability and thermal efficiency of the turbine. Blade cooling is achieved by passing coolant through internal channels roughened with rib turbulators. In this work, the effect of rotation on heat transfer of a square ribbed duct is studied using Large Eddy Simulation (LES) at a Reynolds number based on the average bulk velocity of 20,000. The study compares the heat transfer performance of the square duct roughened with square (SQ) rib, Backward step (BS) rib, and Forward step (FS) rib at three rotation numbers $Ro=0.18, 0.35$ and $0.67.$ In the range of rotation numbers investigated, the overall Nusselt number for SQ, BS, and FS ribs is about 14%, 20%, and 16%, respectively, higher than a non-rotating duct. The overall heat transfer augmentation factor between 3.10 and 3.25 for $0.18\le Ro\le 0.67$ in the duct with BS-ribs is approximately 24% higher than SQ-ribs, while the friction coefficient is higher only by 10–15%.

摘要

涡轮叶片的冷却在提高涡轮的耐用性和热效率方面起着至关重要的作用。叶片冷却是通过使冷却液通过带有肋状湍流器粗糙的内部通道来实现的。在这项工作中，基于 20,000 的平均体积速度，使用大涡模拟 (LES) 在雷诺数下研究了旋转对方形肋管传热的影响。该研究比较了带有方形 (SQ) 肋、后退台阶 (BS) 肋和前进台阶 (FS) 肋的粗化方形风管在三种转速下的传热性能$\mathrm{电阻}○=0.18, 0.35$ 和 $0.67.$在所研究的旋转数范围内，SQ、BS 和 FS 肋的总体努塞尔数分别比非旋转管道高约 14%、20% 和 16%。对于 3.10 和 3.25 之间的整体传热增强系数$0.18\le \mathrm{电阻}○\le 0.67$ 带有 BS 肋的管道中的摩擦系数比 SQ 肋高约 24%，而摩擦系数仅高 10-15%。