宝珠寺电站水轮机转轮裂纹成因分析

Cause Analysis of Runner Crack of Baozhusi Hydropower Station

鉴于宝珠寺水电站投AGC运行后机组在低负荷及空载工况运行时长激增、转轮裂纹突出的问题,从水力设计、材料工艺及机组运行等多角度分析转轮裂纹成因,发现转轮裂纹产生的根本原因是转轮为异种钢分瓣结构,整体结构强度较低,同时转轮历经多次空蚀孔洞补焊,相关部位材料性能降低;主要原因是机组在高水头小流量工况运行时,在上冠及叶片进口背面产生脱流,引起叶片振动,同时上冠与叶片连接处为高应力集中区,长期在此工况运行将导致裂纹产生。

When putting into operation of AGC in Baozhusi Hydropower Station,the unit operates at low and no-load intervals for a long time,and the crack problem of runner is serious.This paper analyzes the causes of runner cracks from the perspectives of hydraulic design,material technology and unit operation.The root cause is that the runner is a dissimilar steel split structure with low overall structural strength.At the same time,the material properties of the relevant parts of the runner are reduced after several repairs welding of cavitation cavities.The main reason is that when the unit operates under the condition of high water head and small flow rate,it will produce flow separation at the top crown and back of blade inlet,which will cause blade vibration.At the same time,the connection between the top crown and blade is a high stress concentration area.Long-term operation under this operating condition will cause cracks.