Influence of Eccentricity on Hydrodynamic Characteristics of Nuclear Reactor Coolant Pump under Different Cavitation Conditions

Yuanyuan Zhao,Bin Lin,Rongsheng Zhu,Xiuli Wang,Qiang Fu

doi:10.3390/pr8010098

Abstract

In order to study the influence of eccentricity on hydrodynamic characteristics of nuclear reactor coolant pump under different cavitation conditions, five different schemes were obtained by analyzing and optimizing the existing structural schemes. Based on the RNG k-ε model (Renormalization Group with k-epsilon turbulence models) and two-fluid two-phase flow model, the unsteady numerical analysis and test verification of different designed schemes are carried out by using the flow field software ANSYS CFX. The results of research show that different eccentricities will affect the nuclear reactor coolant pump’s head under different cavitation conditions, and the corresponding head in the scheme with the eccentricity of 5mm under the fracture cavitation condition is lower than that of the other schemes. When the impeller rotates at a certain angle from the initial position under critical and severe cavitation conditions, the radial force acting on the rotor system will fluctuate greatly. Under the condition of fracture cavitation, the radial force changed periodically and the resultant force value is small. Compared to the original scheme, the peak value of radial force is 6° clockwise after eccentricity of the impeller appeared. With the aggravation of cavitation condition, the axial force value of impeller decreases, but the corresponding amplitude of the impeller increases. Under critical and severe cavitation conditions, the maximum axial force amplitude of the nuclear reactor coolant pump appears in the two times blade frequency, and in the broken cavitation condition, the maximum axial force amplitude appears at the shaft frequency. When the eccentricity is 20 mm, the axial force fluctuates most under critical and severe cavitation conditions, and when the eccentricity is 10 mm, the corresponding axial force is smaller than that of the original scheme. When the eccentricity is 5 mm, the axial force on the impeller is the smallest, but the amplitude is the largest under the condition of fracture cavitation.

Highlights

Despite the disastrous nuclear accident that occurred in Fukushima in 2011, nuclear energy, as a vital part of world energy, will not be affected in the future development [1]
The total inlet pressure corresponding to the critical cavitation, severe cavitation and fracture cavitation total inlet pressure corresponding to the critical cavitation, severe cavitation and fracture cavitation of the the nuclear nuclear reactor reactor coolant coolant pump pump is is carried carried out
AndQn, η begin toηfall sharply with the increase flow, and flow, and the cavitation have developed to a considerable extent at this time

Summary

Introduction

Despite the disastrous nuclear accident that occurred in Fukushima in 2011, nuclear energy, as a vital part of world energy, will not be affected in the future development [1]. The shadow of nuclear accidents cannot be ignored. As one of the core equipment of nuclear power plant, the nuclear reactor coolant pump and its ability to operate safely and steadily for a long time plays a vital role in the safe and stable operation of the whole nuclear power plant [3]. Small break loss of coolant accident (SBLOCA), a commonly analyzed accident condition, will lead to a sharp decrease in environmental pressure, resulting in cavitation in the impeller of the nuclear reactor coolant pump [4,5]. Cavitation will cause the energy exchange of liquid to be interfered and Processes 2020, 8, 98; doi:10.3390/pr8010098 www.mdpi.com/journal/processes

Methods

Results

Conclusion