CFD Numerical Simulation onto the Gas-Liquid Two-Phase Flow Behavior During Vehicle Refueling Process

With the gradual improvement of environmental regulations,more and more attentions are attracted to the vapor emissions during the process of vehicle refueling.Research onto the vehicle refueling process by means of numerical simulation has been executed abroad since 1990s,while as it has never been involved so far domestically.Through reasonable simplification about the physical system of "Nozzle + filler pipe+ gasoline storage tank + vent pipe" for vehicle refueling,and by means of volume of fluid(VOF) model for gas-liquid two-phase flow and Re-Normalization Group k-e turbulence flow model provided in commercial computational fluid dynamics(CFD) software Fluent,this paper determined the proper mesh discretization scheme and applied the proper boundary conditions based on the Gambit software,then established the reasonable numerical simulation model for the gas-liquid two-phase flow during the refueling process.Through discussing the influence of refueling velocity on the static pressure of vent space in gasoline tank,the back-flowing phenomenon has been revealed in this paper.It has been demonstrated that,the more the flow rate and the refueling velocity of refueling nozzle is,the higher the gross static pressure in the vent space of gasoline tank.In the meanwhile,the variation of static pressure in the vent space of gasoline tank can be categorized into three obvious stages.When the refueling flow rate becomes higher,the back-flowing phenomenon of liquid gasoline can sometimes be induced in the head section of filler pipe,thus making the gasoline nozzle pre-shut-off.Totally speaking,the theoretical work accomplished in this paper laid some solid foundation for self-researching and self-developing the technology and apparatus for the vehicle refueling and refueling emissions control domestically.