余热排出泵水中模态分析

为了真实反映转子在水中振动情况,基于流固耦合动力学方程,采用ANSYS WORKBENCH有限元软件,对余热排出泵转子进行水中模态分析.分别计算了转子在空气中,预应力下及水中模态分布,得到相应固有频率及振型,并对比分析预应力和水附加质量对转子振动性能的影响.分析结果表明,预应力提高转子固有频率,变化率为4.42%~22.41%,并且主要提高扭转方向固有频率;水附加质量降低转子固有频率,变化率为4.69%~11.5%,阶数越高,变化率越大,与振动方向无关.在此基础上,根据核电要求对余热排出泵转子临界转速进行计算校核.计算得:第一临界转速5 475.6 r/min和第一扭转临界转速6 694.2 r/min远远超过运行转速1 490 r/min,水力激振频率173.8 Hz也处在安全范围内,符合核电要求.

Modal analysis for rotor of residual heat removal pump in water

In order to truly reflect the rotor vibration in water, the rotor modal of residual heat removal pump was calculated by ANSYS WORKBENCH software based on the fluid-structure interaction kinetics. The modal of rotor and blade were both calculated in air and in water. The natural frequency,mode shape and amplitude were obtained, and the influence of the water medium on rotor vibration performance was discussed. The results show that the water medium has little influence on the low order modes, but significantly reduces the impeller modes. The natural frequency of blade in water has a decline of between 15.9%-49.7% compared to the one in air, mode shape is similar but the amplitude is significantly lower. It is more likely to resonance under the incentive of flow divorced,rotor stator interaction and other excitation force; The decline of the natural frequency has no law, different order comes with different decline. The rotor vibrates in the water, under the impact of water pressure, viscous force and inertial force, the modal result changes. The modal distribution of rotor in water is simulated, which provides a theoretical basis for the prediction of pump dynamic performance and design improvements.