涡轮工作叶片不同区域簸箕形孔的气膜冷却特性实验

Experiment on film cooling characteristics of dustpan shaped holes at different positions of turbine blade

采用压敏漆(PSP)技术实验研究了簸箕形孔在涡轮工作叶片吸力面和压力面不同位置的气膜冷却效率分布特性,分析了吹风比(吹风比为0.5、1.0、2.0)和湍流度(湍流度为0.62%、16.0%对气膜冷却效率的影响规律。实验结果表明:吸力面和压力面上的簸箕形孔最佳吹风比分别在M=1.0和M=2.0附近,吸力面上的簸箕形孔在低湍流度和中等吹风比(吹风比为1.0)下具有较高的气膜冷效,压力面上的簸箕形孔在高吹风比和高湍流度下具有更大的气膜覆盖面积和气膜冷效;吸力面的气膜覆盖面积和展向平均气膜冷效整体显著高于压力面,压力面曲率较大处的簸箕形孔气膜冷效最差。湍流度对气膜冷效的影响程度与吹风比相当;湍流度增强使得压力面气膜冷效降低,但提高了吸力面在高吹风比下的气膜冷效,同时降低了吸力面气膜冷效对吹风比变化的敏感性。

The distribution characteristics of film cooling effectiveness of dustpan shaped holes at different positions of suction surface and pressure surface of turbine blade were studied by pressure sensitive paint(PSP)measurement technique.The effects of blowing ratio(blowing ratio of 0.5,1.0,2.0)and turbulence intensity(turbulence intensity of 0.62%,16.0%)on film cooling effectiveness were analysed.The experimental results showed that the optimum blowing ratios of the dustpan shaped holes on the suction surface and pressure surface were around blowing ratio of 1.0 and 2.0,respectively.The dustpan shaped holes on the suction surface had higher film cooling effectiveness under low turbulence and medium blowing ratio(blowing ratio of 1.0).The dustpan shaped holes on the pressure surface had larger film coverage area and film cooling effectiveness under high blowing ratio and high turbulence.The film coverage area and spanwise averaged film cooling effectiveness on the suction surface were significantly higher than those on the pressure surface.And the film cooling performance of dustpan shaped holes at the position with large curvature was the worst on the pressure surface.The influence of turbulence on film cooling effectiveness was similar to that of blowing ratio.The enhancement of turbulence reduced the film cooling effectiveness on the pressure surface,but improved the film cooling performance on the suction surface under high blowing ratio,and reduced the sensitivity of the film cooling performance to the change of blowing ratio on the suction surface.