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| Fatigue analysis of hydro-turbine head cover bolts based on prototype vibration measurement |
| LIAN Jijian, WANG Tingjie, WANG Haijun*, WANG Hongzhen |
| State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China |
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Abstract Taking a high-head hydropower plant in China as an example, vibration of the head cover in a real hydro-turbine was mearued and analyzed under steady variable load, startup and shutdown, load-rejection conditions. A fininte element model was established for the head cover and connecting bolts, the fluctuating presure load on the head cover was detemiend inversely by making using finite element dynamic analysis base on the measured data. Fatigue of the bolts was anlayzed in normal ope-rating and load-rejection conditions by utilizing linear fatigue cumulative damage theory and rainfall counting method and by adopting actual operation modes of the turine in one year. The results indicate that the pressure fluctuating double amplitude is about 19.3 m on the head cover under 100 MW steady operating condition, which is 5.6 times that under 600 MW condition. Fatigue life of the bolts decreases sharply along with increase of survival rate. When the survival rate is increased from 95% to 99% under 100 MW condition, the fatigue life is decreased to 2.415×107 from 6.488×107, and the reduction is 62.8%. Taking 99% as a survival rate criteria, the fatigue life of the bolts is 7.494×105 under load-rejection condition, which accounts for only 3%-5% of that under various steady load conditions.
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Received: 02 August 2019
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