后加载和高负荷前加载叶型气动性能的试验研究

Experimental Investigations on the Aerodynamic Performance of the Aft-Loaded and Fore-Loaded Turbine Cascades

采用平面叶栅和环形叶栅吹风试验对后加载和高负荷前加载叶型的气动性能进行了详细的测量和研究.在平面叶栅吹风试验中,测量了2种叶型的压力系数分布,研究了攻角、相对栅距、安装角和马赫数的变化对叶型能量损失系数的影响规律.在环形叶栅吹风试验中,测量了2种叶型的近叶顶、中叶高和近叶根处的压力系数分布以及能量损失系数沿叶高的变化规律.对后加载和高负荷前加载叶型的三维成型规律进行了讨论.试验结果表明:高负荷前加载叶型相对于后加载叶型具有更大的负荷特性;高负荷前加载叶型在采用较大的切向弯曲后可以抑制二次流的发展和减少二次流损失;前加载叶型和后加载叶型均具有优良的气动性能.研究结果对于拓宽高性能叶型在汽轮机中的应用提供了理论基础和技术支持.

The aerodynamic performance of the aft-loaded and fore-loaded turbine blade was investigated using the linear and annular turbine cascades experiments. The linear cascade experimental rig was utilized to measure the pressure distribution along the aft-loaded and fore-loaded turbine blade. Moreover, the effects of the variations of the cascade pitch, stagger angle, attack angle and Mach number on the efficiency of aft-loaded and fore-loaded turbine blade were examined. The annular cascade experimental rig was applied to measure the pressure distribution along the aft-loaded and fore-loaded turbine blade at the near tip, mid-span and near hub three typical blade heights. The energy loss coefficients distribution along the blade height was also measured for both the aft-loaded and fore-loaded blades. Further, the effects of the three-dimensional curved stacking method on the cascade performance were discussed according to the annular experimental results. The results show that the larger circumferential bowed blade can be able to suppress the secondary flow loss and improve the aerodynamic performance for the fore-loaded turbine blade. In addition, the load of the fore-loaded blade was higher than that of the aft-loaded blade.