Abstract As a new kind of advanced cooling technique, steam cooling has been applied in modern high temperature gas turbine blade cooling for improving the turbine efficiency. The superheated steam is selected as coolant to replace traditional compressor air as closed loop steam cooling for the internal convective cooling. This paper experimentally and computationally investigates the cooling performance of internal steam convective cooling in a nozzle guide vane with five smooth radial cooling ducts. Experiments are conducted on a linear turbine cascade at exit Mach numbers of 0.9, and exit Reynolds number of 1.2 × 106. Temperature and static pressure on the cooled vane surface are measured at the mid span for a range of coolant-to-mainstream temperatures ratio and coolant-to-mainstream mass flow ratio. The numerical investigations using the conjugate calculation technique are also performed to predict the complex three dimensional flow and heat transfer. The k–ω based Shear–Stress-Transport (SST) model is selected as the turbulence model. It can be found that the numerical results of vane temperature are underestimated compared with experimental data, especially at the trailing edge. The coolant steam has much higher cooling effectiveness than air, about 12%. The cooling effectiveness at the vane middle chord region is much higher than that at the leading and trailing region, by approximately 50% and 20%, respectively, which will lead to great temperature gradient and thermal stresses at the leading and trailing region. Therefore, more complicated cooling configuration besides convective cooling may be necessitated for this vane.

中文翻译：

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汽冷式燃气轮机喷嘴导叶冷却性能分析

摘要 蒸汽冷却作为一种新型的先进冷却技术，已应用于现代高温燃气轮机叶片冷却，以提高涡轮机效率。选用过热蒸汽作为冷却剂，替代传统压缩机空气作为闭环蒸汽冷却进行内部对流冷却。本文通过实验和计算研究了具有五个光滑径向冷却管道的喷嘴导向叶片中内部蒸汽对流冷却的冷却性能。实验在线性涡轮叶栅上进行，出口马赫数为 0.9，出口雷诺数为 1.2 × 106。在冷却剂与主流温度比的范围内，在中间跨度处测量冷却叶片表面的温度和静压和冷却剂与主流的质量流量比。还进行了使用共轭计算技术的数值研究，以预测复杂的三维流动和传热。选择基于 k-ω 的剪切-应力-传输 (SST) 模型作为湍流模型。可以发现，与实验数据相比，叶片温度的数值结果被低估了，尤其是在后缘处。冷却剂蒸汽的冷却效率比空气高得多，约为 12%。叶片中弦区的冷却效率远高于前、后区，分别约为50%和20%，这将导致前、后区产生较大的温度梯度和热应力。因此，除了对流冷却之外，该叶片可能需要更复杂的冷却配置。