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Dynamic analysis of the axial vibration of the impeller in a reactor coolant pump induced by the radial leakage flow[J].计算力学学报,2018,35(4):458~465

Dynamic analysis of the axial vibration of the impeller in a reactor coolant pump induced by the radial leakage flow
Dynamic analysis of the axial vibration of the impeller in a reactor coolant pump induced by the radial leakage flow

DOI：10.7511/jslx20170328001

 作者 单位 E-mail 李姿琳 大连理工大学 工程力学系工业装备结构分析国家重点实验室, 大连 116024 徐胜利 大连理工大学 能源与动力学院, 大连 116024 关振群 大连理工大学 工程力学系工业装备结构分析国家重点实验室, 大连 116024 guanzhq@dlut.edu.cn

具有径向流的间隙结构广泛存在于轴承结构与旋转机械中，间隙中的流固耦合作用可能影响整体结构的运动稳定性。基于理论间隙模型和核主泵的实际结构，本文对径向间隙流引起的轴向振动进行了多方面的研究。当间隙的一个壁面产生轴向振动并处于旋转状态时，壁面受到由径向流引起的时变轴向力，因此间隙为叶轮提供附加的轴向刚度和阻尼。通过研究以水为介质的理论间隙模型，发现径向间隙流会引起负的等效轴向动力系数（刚度和阻尼），并且流道形状是影响间隙轴向动力特性的重要因素。扩张流道和平行流道会产生负的轴向动力系数，特别是负阻尼会引起结构振动发散；而收缩流道间隙具有稳定的轴向动力特性。最后，对AP1000核主泵原型叶轮间隙模型进行分析，结果表明，间隙会引起轴向负刚度，并且在一定工况下出现负阻尼，此时系统轴向稳定性及结构安全运行将受到严重的不良影响。

This paper studies the axial dynamic characteristics of leakage-flow-induced vibration of a theoretical model and a real clearance between the shroud and impeller of a reactor coolant pump.Since structures like bearings and rotating machineries all have leakage flow problems,dynamics of the clearance will affect the stability of the system.In the case when the wall of clearance is rotating with respect to the axis while vibrating in the axial direction,the fluid force acting on the wall changes,therefore the dynamic characteristics of the clearance can be approximately described by the dynamic characteristics:stiffness and damping.Three types of clearance,including the flat clearance,the enlarged clearance and the contracting clearance,are analyzed in this paper and negative stiffness or damping characteristics can be seen in both of the flat clearance and enlarged clearance cases.In contrast,the contracting shape clearance is better as its stiffness and damping are always positive.Research on axial dynamic characteristics of the clearance between the shroud and impeller of a reactor coolant pump is carried out and results show negative stiffness and damping of this clearance in some cases.This clearance is an unstable factor to the system.