Numerical simulation of flow pattern map of upward two-phase flow in vertical rectangular channel

The flow pattern plays a fundamental role in analysis of heat transfer,flow instability and critical heat flux in two-phase flow.Based on the VOF(Volume of Fluid) multiphase model,a numerical simulation of upward gas-liquid two-phase flow in vertical rectangular channel has been investigated.The superficial velocity ranges from 0.1 to 110 m/s for gas,and from 0.1 to 3.2 m/s for liquid.The results show that the main flow patterns of gas-liquid two-phase flow in the channel are bubbly flow,slug flow,churn flow and annular flow.The simulation reveals the connections between the void fraction distribution and flow patterns,and the relationship between the void fraction and the volume fraction of gas-phase flow.The pressure drop characteristic is analyzed under different flow patterns.The flow pattern map is drafted based on the apparent gas-liquid kinetic energy flux under different mass flow rate,and the map shows the distribution of various flow patterns and the transition boundary among flow patterns.The simulation agrees well with the experimental results in the published literature.