涡轮叶片前缘旋流-气膜复合冷却内部流动传热特征实验和数值模拟

Experiment and Numerical Simulation on Internal Flow and Heat Transfer of Swirling Flow-Film Cooling for Leading Edge of Turbine Blade

关键词:  涡轮叶片冷却  叶片前缘  旋流-气膜冷却  数值模拟  热色液晶（TLC）

Key words:  Turbine blade cooling  Blade leading edge  Swirling flow-film cooling  Numerical simulation  Thermochromic liquid crystal

摘要:

为了提高涡轮叶片前缘的冷却效率，提出了一种偏置冲击孔的旋流-气膜冷却结构。在雷诺数2×10⁴～5×10⁴时，对冲击孔居中和偏置分别开展实验研究和数值模拟，得到了两种结构的内部传热、流阻和流场特性。实验通过瞬态液晶热像技术获得前缘内表面的详细努塞尔数分布，并结合数值模拟的结果分析了流场特征，对强化换热的机理做出解释。实验结果表明：叶片前缘内部旋流使总体平均努塞尔数提高4.0%~9.4%，同时压力损失降低5.6%~6.4%。数值模拟结果表明，偏置冲击孔利用叶片前缘曲率较大的结构特性产生了强烈的旋流，使高换热区的面积显著增加，改善了内部换热的均匀性。

Abstract:

A swirling flow-film cooling structure with offset impingement holes is proposed to achieve higher cooling efficiency of turbine blade leading edge. Experimental investigations and numerical simulations were carried out on two structures distinguished by whether impingement jets are tangential-wisely offset from the centerline with Reynolds number ranging from 2×10⁴ to 5×10⁴. The internal heat transfer， flow resistance， and flow field characteristics were obtained. Transient liquid crystal thermal imaging technique was used in experiments to measure detailed Nusselt number distributions on the inner surface of leading edge， and the flow field was analyzed with the results of numerical simulation to explain the mechanism of heat transfer enhancement. Experimental results show that internal swirling flow of blade leading edge can improve the overall average Nusselt number by 4.0%~9.4% and reduce the pressure loss by 5.6%~6.4%. Numerical results suggest that tangential jets create intense swirling flow because of the concave surface of blade leading edge， which significantly enlarges the high heat transfer region and improves the uniformity of internal heat transfer.