内部结构对空冷叶片换热性能的影响

The Influence of Inner Structures on the Heat Exchange Performance of Air-cooled Blades

为了深入了解空冷透平动叶的冷却机理和冷气流动特性,对某型燃气轮机透平动叶进行了气-热耦合数值模拟。结果表明,叶片端部气膜孔可以促进冷气在蛇形通道中的流动,改善冷却效果;涡流矩阵通道中子通道的宽度与高度比减小会加大涡流矩阵通道中的流动阻力,冷气在涡流矩阵通道中能得到更充分的利用,而对尾缘的冷却能力会下降,致使尾缘温度升高,因此其高宽比与冷气进口条件存在一个最佳组合关系;涡流矩阵通道结构与叶尖之间的间隙会降低冷气的利用率。

To gain a profound understanding of the cooling mechanism and cold-air flow characteristics of air-cooled turbine buckets,an air-thermal coupled numerical simulation has been conducted of the buckets in question.It has been found that blade tip air-film holes can speed up the cold air flow in the coil-tube passages and improve cooling effectiveness.The reduction of the width-height ratio of the sub-channel in the vortex matrix passage can increase the flow resistance in the affected passage,leading to a fuller utilization of the cold air in the passage.However,this may lower the cooling capacity of the cold air and contribute to a temperature rise at the trailing edge.Hence,there exists an optimum make-up relationship between the width-height ratio and the cold-air inlet condition.Furthermore,the clearance between the vortex matrix passage structure and the blade tip may lower the utilization rate of the cold air.