Film Cooling and Heat Transfer on Two Cutback Trailing Edge Models With Internal Perforated Blockages
Film Cooling and Heat Transfer on Two Cutback Trailing Edge Models With Internal Perforated Blockages
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DOI：
10.1115/1.2780174
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发表时间：
2008
影响因子：
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通讯作者：
Jung-ho Choi;S. Mhetras;Je-Chin Han;Sai C. Lau;R. Rudolph
中科院分区：
文献类型：
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作者：
Jung-ho Choi;S. Mhetras;Je-Chin Han;Sai C. Lau;R. Rudolph
对带缝隙引射的涡轮机叶片切短尾缘气膜冷却和换热进行了实验研究。研究了在冷却剂喷入自由涡壳之前，两排穿孔堵塞插入件对冷却剂通道壁面的侧向冲击传热。内部试验几何形状类似于现代燃气涡轮机叶片后缘冷却所用的交叉冲击孔设计。采用基于色调值检测的液晶显示技术，对带缝隙引射的尾缘气膜冷却模型和带穿孔堵塞物的内模进行了换热系数的测量。它也被用来确定削减后缘上的油膜效率。对于带穿孔堵塞插入件的内部模型，基于槽的水力直径和出口速度的雷诺数分别为5000、10，000、20，000和30，000，对于带槽喷射的外部模型，相应的冷却剂与自由流速度比范围分别为0.26至1.83。针对两种不同的设计1和2进行实验，其中设计1结合了具有交错/直列槽出口布置的两种不同配置，并且设计2具有交错槽出口布置。两种设计都利用90度气流转向进入堵塞插入件作为试验段的入口，以模拟真实的叶片通道设计。结果表明，后缘的内部设计几何形状和雷诺数会影响带有穿孔堵塞插入物的内部模型中的传热。设计2具有更宽的入口通道和靠近喷射槽的斜坡，在内部和外部模型中提供了较低的传热系数，但从槽喷射获得了更高的膜冷却效率。
Experiments to study heat transfer and film cooling on the cutback trailing edge of a turbine blade with slot ejection were performed. Heat transfer from two rows of perforated blockage inserts for lateral impingement on the coolant channel walls prior to coolant ejection into the freestream was also investigated. The internal test geometry is similar to the crossover impingement hole design used in modern gas turbine blades for trailing edge cooling. A liquid crystal technique based on hue value detection was used to measure the heat transfer coefficient on a trailing edge film-cooling model with slot ejection and an internal model with perforated blockage inserts. It was also used to determine the film effectiveness on the cutback trailing edge. For the internal model with the perforated blockage inserts, Reynolds numbers based on the hydraulic diameter of the slot and exit velocity were 5000, 10,000, 20,000, and 30,000 and corresponding coolant-to-freestream velocity ratios ranged from 0.26 to 1.83 for the external model with slot ejection, respectively. The experiments were performed for two different designs, 1 and 2, with Design 1 incorporating two different configurations with a staggered/inline slot exit arrangement and Design 2 with a staggered slot exit arrangement. Both designs utilized a 90 deg flow turn into the blockage inserts as an entrance to the test section to simulate a realistic blade passage design. Results show that the internal design geometry of the trailing edge and Reynolds numbers can affect heat transfer in an internal model with perforated blockage inserts. Design 2 with a wider entrance channel and a sloped land near the ejection slots provided low heat transfer coefficients in the internal as well as external model but gave higher film-cooling effectiveness from slot ejection.