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为大型水轮机组的安全、稳定运行,研究了转轮在水介质中的动力特性。运用顺序耦合的方法,分析了在三维旋转流动所产生的水压力作用下转轮体的静强度特性;运用全流固耦合的三维有限元方法进行了转轮在水介质中的模态分析。强度分析结果表明,应力集中的部位与裂纹实际产生的位置完全吻合,但最大等效应力远小于材料的极限破坏应力;模态分析得到转轮在水中的自振频率和振型等振动特性,指出了发生共振的可能性。结果证实了导致裂纹产生的原因不是静应力而是动载荷的作用。
In this paper, the dynamic characteristics of runner in water medium are studied for the safe and steady operation of large hydraulic turbine. Using the method of sequential coupling, the static strength characteristics of the wheel body under water pressure generated by the three-dimensional rotating flow are analyzed. The modal analysis of the wheel in the water medium is carried out by using the full three-dimensional finite element method. The results of strength analysis indicate that the site of stress concentration exactly coincides with the actual location of the crack, but the maximum equivalent stress is much smaller than the ultimate failure stress of the material. The vibration characteristics such as natural frequency and mode shape of rotor in water are obtained by modal analysis. Pointed out the possibility of resonance. The results confirmed that the cause of the crack was not the static stress but the dynamic load.