Research on lift model of two-phase flow in sub-channels of nuclear power plant fuel assembly

Abstract

In nuclear power plants, it is the most basic principle to ensure the nuclear safety. The gas-liquid two-phase flow is widely observed in the nuclear energy systems, for example, in the boiling water reactors, steam generators, and cores of the pressurized water reactor in accident conditions. Two-phase flow is a state that cannot be ignored, in which the void distribution in the two phases has a significant impact on temperature measurement, liquid level measurement and instrument control. Therefore, the importance of the study of two-phase flow in nuclear power plants is self-evident. Accurate simulation and research of two-phase flow has become a difficult point in today's research. In the simulation of two-phase bubbly flow, the momentum exchange between the phases requires lift. In the past, many models with reasonable accuracy have been developed for these lift forces. However, no agreement has been reached on a generally applicable model combination of these lift forces. Choosing a suitable model for these lift forces is very important to successfully predict the bubble concentration distribution and velocity distribution. At present, the elevator models are selected from many models, and most of them are based on specific models. Therefore, this article summarizes the current status of lift models in the computational fluid dynamics simulation of two-phase bubbly flow, and reviews the parameter dependence and application range of these models. In addition, some limitations of these enhancement models have been identified.