CFD simulation focusing on void distribution of subcooled flow boiling in circular tube under rolling condition

Abstract

A numerical investigation of void fraction distribution of subcooled flow boiling in circular tube under rolling condition has been performed based on the RPI method. In this paper, the rolling motion is considered by UDF (user-defined function) and coupled with CFD code to realize the rolling motion. Numerical simulation is verified by comparing the simulation result with experimental result. The CFD simulation results under both static and rolling conditions agree well with the experimental data. Different working conditions are studied in this paper, and detail analysis is presented to discuss the effect of working conditions on the void distribution. With different rolling periods, it is found that the local void fraction distribution is different. When the rolling period is bigger than 4 s, the local maximum void fraction decreases with the increasing period. When the rolling period is less than 4 s, the local maximum void fraction increases with the increasing period. For the working conditions with different rolling amplitudes, the maximum local void fraction increases with increasing amplitude. Based on the analysis of flow field and phase distribution, the local two-phase flow heat transfer coefficient fluctuates periodically with the rolling motion.