基于调峰工况的汽轮机调节级叶型优化设计

Optimization Design on Blade Profile of Governing Stage in Steam Turbinebased on Peak Regulating Condition

采用了遗传算法迭代优化理论对调节级的叶型进行NURBS曲线寻优,得到了基于调峰工况下的优化叶型,并数值研究了叶型优化前、后的调节级级内流场的流动形态、叶片载荷分布和叶栅内损失的发展规律。研究结果表明:叶型优化后,更大的动叶前缘直径能有效降低小容积流量时汽流攻角对流场的影响,更流畅的背弧和更薄的出口边能使调节级叶栅通道内端壁损失减少,二次流的影响区域变小,叶片的载荷增大,叶片表面的附面层厚度得到有效的抑制,叶型损失降低,流动效率有所提高。优化后叶栅不仅在调峰工况性能改善明显,而且在设计工况同样具有良好的性能。

The iterative optimization theory of genetic algorithm is used to optimize the NURBS curve of blade profile in governing stage.The optimized blade profile based on peak regulating condition is obtained.The flow pattern of internal flow field,the load distribution of stator blade and the development law of cascade losses are studied before and after blade profile optimization.The results show that after blade profile optimization,larger rotor blade leading edge diameter can effectively reduce the influence of steam attack angle on the flow field when the volume flow rate is small.The smoother suction surface and thinner exit edge can reduce the end wall loss in the cascade passage,which leads to the reduction of the influence area of secondary flow,the increase of blade load,the effective restraint of the boundary layer thickness on the blade surface,the reduction of blade profile loss,and the improvement of flow efficiency of the governing stage.The optimized blade not only improves the performance in the peak regulating condition,but also has good performance in the design condition.