边倒圆型气膜孔流动换热特性研究

Experimental and Numerical Study on Film Cooling Performance of Radiusing-Type Hole

关键词:  涡轮叶片  气膜冷却  边倒圆型气膜孔  实验研究  数值模拟

Key words:  Turbine blade  Film cooling  Radiusing-type hole  Experimental study  Numerical simulation

摘要:

为提高涡轮叶片气膜冷却效率，根据主流与射流间的相互作用关系，并以圆柱型气膜孔为基础，在气膜孔出口前缘位置进行边倒圆处理，同时对该新型的边倒圆型气膜孔结构进行了实验及数值计算研究。分析了边倒圆型气膜孔的流动换热机理，得到了新型气膜孔下游全表面气膜冷却特性分布及气膜孔的流量系数。结果表明:边倒圆型气膜孔内流动均匀，出口涡强度有所降低，进而能够减弱主流通道内的反转对涡强度；同时由于边倒圆孔的扩张作用使得射流法向动量降低、展向动量增强，从而提高气膜冷却效率。边倒圆型气膜孔的孔下游区域气膜贴壁性较好，气膜展向覆盖面积较大。相比于圆柱型气膜孔，边倒圆型气膜孔下游区域换热系数较高，远孔区域换热系数较小。新型气膜孔的流量系数比圆柱型气膜孔约大5%，孔内流动损失较小。整体上看，边倒圆型气膜孔具有较好的流动换热特性。

Abstract:

In order to get higher film cooling performance， a new structure called radiusing-type hole was proposed based on cylinder hole and the interaction between mainstream and jet of film cooling. Medication of radiusing was used near the leading edge of film cooling hole. Experiments and numerical simulations were conducted to figure out the flow and heat transfer performance of radiusing-type hole. Film cooling characteristics downstream of the hole and discharge coefficient were studied. Results show that flow structure within the radiusing-type hole is more uniform than cylindrical hole which leads to weaker kidney vortex pairs in main flow. Normal momentum of jet is weaker and lateral momentum is stronger because of the expanding effect of radiusing-type hole， these two factors improve film cooling performance. For radiusing-type hole， the film attach on the wall better and cover wider area. In the region downstream the exit of radiusing-type hole， heat transfer coefficient is high， along the stream wise direction heat transfer coefficient is sharply decreased. The discharge coefficient of radiusing-type hole is 5% higher than cylindrical hole. In general， radiusing-type hole has better flow and heat transfer characteristics.