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首页> 外文期刊>International Journal of Heat and Mass Transfer >Numerical model validation and prediction of mist/steam cooling in a 180-degree bend tube
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Numerical model validation and prediction of mist/steam cooling in a 180-degree bend tube

机译：180度弯管内雾/蒸汽冷却的数值模型验证和预测

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摘要

To achieve higher efficiency target of the advanced turbine systems, the closed-loop steam cooling scheme is employed to cool the airfoil. It is proven from the experimental results at laboratory working conditions that injecting mist into steam can significantly augment the heat transfer in the turbine blades with several fundamental studies. The mist cooling technique has to be tested at gas turbine working conditions before implementation. Realizing the fact that conducting experiment at gas turbine working condition would be expensive and time consuming, the computational simulation is performed to get a preliminary evaluation on the potential success of mist cooling at gas turbine working conditions. The present investigation aims at validating a CFD model against experimental results in a 180-degree tube bend and applying the model to predict the mist/steam cooling performance at gas turbine working conditions. The results show that the CFD model can predict the wall temperature within 8% of experimental steam-only flow and 16% of mist/steam flow condition. Five turbulence models have been employed and their results are compared. Inclusion of radiation into CFD model causes noticeable increase in accuracy of prediction. The reflect Discrete Phase Model (DPM) wall boundary condition predicts better than the wall-film boundary condition. The CFD simulation identifies that mist impingement over outer wall is the cause for maximum mist cooling enhancement at 45° of bend portion. The computed results also reveal the phenomenon of mist secondary flow interaction at bend portion, adding the mist cooling enhancement at the inner wall. The validated CFD simulation predicts that average of 100% mist cooling enhancement can be achieved by injecting 5% mist at elevated GT working condition.
机译：为了达到先进涡轮系统更高效率的目标，采用了闭环蒸汽冷却方案来冷却翼型。在实验室工作条件下的实验结果证明，通过一些基础研究，将雾气注入蒸汽中可以显着增强涡轮叶片中的热传递。在实施之前，必须在燃气轮机的工作条件下对雾冷却技术进行测试。认识到在燃气轮机工作条件下进行实验既昂贵又耗时的事实，进行了计算仿真，以初步评估在燃气轮机工作条件下雾冷却的潜在成功性。本研究旨在针对180度弯管中的实验结果验证CFD模型，并应用该模型预测燃气轮机工作条件下的薄雾/蒸汽冷却性能。结果表明，CFD模型可以预测壁温在纯蒸汽实验流量的8％内和薄雾/蒸汽流量条件的16％内。使用了五个湍流模型，并比较了它们的结果。将辐射包括在CFD模型中会大大提高预测的准确性。反射离散相模型（DPM）壁边界条件的预测要好于壁膜边界条件。 CFD仿真表明，雾在外壁上的撞击是在弯曲部分45°处最大程度地增强雾冷却的原因。计算结果还揭示了弯曲部分雾气二次流相互作用的现象，在内壁增加了雾气的冷却作用。经过验证的CFD仿真预测，通过在升高的GT工作条件下注入5％的雾气，可以平均提高100％的雾气冷却。

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