Session: 03-08-03: Computational Modeling and Simulation for Advanced Manufacturing

Paper Number: 145416

145416 - Dynamic Analysis of Main Coolant Pump Based on Precise Integration Method 

The non-uniform axial thrust load caused by manufacture, assembly and the transverse response of a rotor will probably affect the stability and reliability of rotor-bearing system in main coolant pump in nuclear power plants. Thus, the adaptive equalizing beam structure which lapped by a set of the sector beam is developed as a particular supporting system for the large tilting pad thrust bearing to make a uniform axial thrust load of the thrust bearing in the rotor-bearing system. However, the effect of adaptive equalizing beam structure on the dynamic response of rotor-bearing system in the main coolant pump is not clear. In this work, a coupled longitudinal-transverse dynamics model for a rotor-bearing system with the adaptive equalizing beam structure is developed by combining finite element and spring-mass system. The precise integration method is employed to solve the stiffness problem caused by difference of axial and radial stiffness for the rotor-bearing system with the adaptive equalizing beam structure. Furthermore, very high-precision solution could be achieved in almost arbitrary time step by using the precise integration method. Based on the proposed model, the influence of operating condition parameters and structure parameters of adaptive equalizing beam structure on dynamic response of the rotor-bearing system is investigated and discussed in details. The following main conclusions can be drawn from the proposed numerical model: (1) The improved precision integration algorithm is used to accurately solve the model and perform dynamic analysis. The algorithm solves the problem of multi-scale time in the dynamic solution, which is caused by the difference in the natural frequency of the main pump. At any time step, the calculation precision can reach the order of 10^-9. (2) Because of the thrust bearing, as the speed gradually increases, the rotor amplitude has experienced a response process of first increasing-then decreasing-then increasing. It explains the phenomenon of increased vibration at 1045 rpm during the experiment of the canned reactor coolant pump. (3) As the pre-tightened force increases, the transverse and longitudinal displacements of the rotor system decrease. On the other hand, the reduction of the thickness of the thrust bearing liquid film during the rotor starting process will cause severe wear. Therefore, an appropriate pre-tightened force must be selected to reduce the vibration amplitude while ensuring a sufficient liquid film thickness. This model provides a basis for the pre-tightened force design and assembly of thrust bearings.

Presenting Author: B. Zhu Dalian University of Technology

Presenting Author Biography: Bao ZHU received the B.S. degree in engineering mechanics from Dalian university of technology, China, in 2005 and the Ph.D. degree in computational mechanics from Dalian university of technology, China, in 2013. He is currently working at the School of Material Science and
Engineering, Dalian University of Technology, China. His research interests include surface engineering and tribology.

Authors:

B. Zhu Dalian University of Technology
Yang Feng Dalian University of Technology
M. K. Lei Dalian University of Technology