针对立式凝结水泵电机存在两个临界转速且两个方向振动相互矛盾的问题，开展现场动平衡试验与理论计算分析。基于有限元方法对凝结水泵进行模态与谐响应分析，提出新型支撑结构设计方案。结果表明：凝结水泵电机的非对称支撑结构（检修人孔）是导致相互垂直两个方向存在两个相近临界转速（约986 r/min、1 177 r/min）的主要原因；临界点附近振动主要为一倍频，然而通过传统动平衡方法无法同时降低两个临界点振动，两个方向相互矛盾，主要是由于两个临界点之间相位差超过180°，转子发生反进动，转子涡动轨迹的长、短轴方向发生改变所导致；在检修人孔布置伸缩顶杆（直径48 mm）可有效改善结构不对称问题，尤其是在检修人孔中心及单侧增加伸缩顶杆可使两个方向固有频率差降至约0.19 Hz，此时凝结水泵电机部分的周向结构刚度达到对称，可有效解决刚度不对称引起的相互垂直方向振动矛盾问题

For the vertical condensate pump motor with two critical speeds and contradictory vibration problems, field dynamic balance experiments and theoretical calculation were carried out. The modal and harmonic response analysis of the condensate pump based on the finite element method was performed to propose a new support structure design scheme. Results show that the asymmetric support structure of the condensate pump motor (maintenance manhole) is the main reason for the existence of two similar critical speeds (about 986 r/min and 1 177 r/min) in two mutually perpendicular directions; the vibration near the critical point is mainly dominated by rotational frequency, however, the vibration of the two critical points cannot be reduced simultaneously by the traditional dynamic balancing method. The vibrations in two directions contradict each other. It is mainly due to the phase difference between the two critical points of more than 180°, the rotor backward whirling and the change of the long and short axis directions of the rotor whirling orbit; the arrangement of telescopic rod 〖JP2〗with a diameter of 48 mm around the maintenance manhole can effectively improve the structural asymmetry problem. Especially by adding telescopic rod in the center and on the single side of the maintenance manhole can reduce the difference of the natural frequency in the two directions to about 0.19 Hz. At this time 〖JP3〗the circumferential structural stiffness of the condensate pump motor part reaches symmetry, which can effectively solve the conflicting problems of vibration in mutual vertical direction caused by stiffness asymmetry.

TK730.2