基于“喷射效应”的高压涡轮叶顶主动冷却机理研究

Active cooling mechanism research of high pressure gas turbine blade tip based on injection effect

为了研究气膜孔"喷射效应"对燃气轮机涡轮凹槽状叶顶传热特性的影响,基于实验模型,通过数值计算研究分析了典型吹风比、不同进气角等多种工况下凹槽内冷却气流的叶顶喷气冷却机理。研究结果表明:进气角产生的叶顶"喷射效应"改变了气膜孔出口处的速度场与流动结构;吹风比M=1.5,进气角β<0°时,进入凹槽肋角区冷气量增多,有效改善了局部壁面的换热,但同时增加了间隙入口处泄漏流的速度与湍动能强度;随着吹风比的增加,进气角对壁面传热Nu数有较大的影响,冷却气体降低了整体Nu值以及底部壁面的Nu峰值,有效改善了换热性能。

Tip cooling mechanism was investigated through CFD based on the experiment modle,including typical blow ratio,different inlet angles in order to investigate the injection effect on heat transfer characteristic of gas turbine grooved blade.Results show that blade tip injection effect induced by inlet angles changes the speed and flow structure around the film hole.When the blowing ratio M is 1.5 and the inlet angle β less than 0°,more cooling air will come into the concavity area of the grooved blade.This will improve the heat transfer characteristic of the local area,but will also increase the speed of the leakage flow around the clearance inlet area.When the blowing ratio increases,effect of the inlet angle on Nu will increase.The cooling air decreases the Nu and the peak Nu of the bottom area of the grooved blade which obviously improves the heat transfer characteric.