叶片全表面换热系数和冷却效率的实验测量

Measurements of Heat Transfer Coefficient and Film Cooling Effectiveness Distribution on a Vane Using Transient Liquid Crystal Technique

采用瞬态液晶技术测量了涡轮导叶叶片全表面的换热系数和冷却效率.实验叶片前缘区域有5排复合角度圆柱形气膜孔,压力面有10排圆柱形孔,吸力面有2排圆柱形孔和2排扇形孔,气膜孔排由2个供气腔供气.实验叶栅由3个直叶片构成,叶栅进口雷诺数是1.1×105,前腔二次流与主流的质量流量比为5.87%,后腔为1.06%.实验测量获得了叶片表面换热系数和冷却效率的二维分布云图,结果表明:气膜孔下游的换热系数和冷却效率都较高;扇形孔下游的冷却效率比圆柱形孔的高;受叶栅通道涡的影响,吸力面气膜覆盖区域收缩,压力面气膜覆盖区域扩张;吸力面换热系数分布受气流分离和通道涡影响.

The Heat transfer coefficient and the film cooling effectiveness were measured on a turbine NGV airfoil employing the transient liquid crystal technique. There are five rows of compound angle cylinder film holes on the showerhead, 10 rows of cylinder holes on the pressure side, two rows of cylinder holes and two rows of fan-shaped holes on the suction side. All the film cooling gas are supplied by two plenums. The measurements were conducted for a three-vane linear cascade at an inlet Reynolds number of 1.1× 10^5, a mass flow ratio of 5. 87% in the first plenum and 1. 060% in the second plenum. Detailed distributions of the heat transfer coefficient and the film cooling effectiveness were obtained. The result shows that the heat transfer coeffi- cient and the film cooling effectiveness are higher in the near hole region,and the fan-shaped hole displays higher film cooling effectiveness than the cylinder hole. The film cover region shrinks on the suction side and expands on the pressure side by the influence of passage vortex. In addition, the heat transfer distribution on the suction side is influenced by the flow separation and the passage vortex.