Two phase pipe flows in fuel tank refueling

Abstract

Automotive fuel tank refueling is modelled with FLUENT software which is a commercial CFD solver in fluid mechanics. Fuel tank components are modeled geometrically such as the fill pipe, vent pipe and tank dome. Additionally, the other important components are modelled as boundary conditions such as fuel nozzle and rollover valve. In FLUENT continuity, momentum, volume fraction and turbulence equations are solved. Gasoline and air are used as materials in the flow. The effect of pressure inside the tank dome to the flow, gasoline inlet velocity and fuel ratio in the fuel nozzle, different fuel nozzle angles, different fill pipe geometries are discussed in this thesis. In some cases premature nozzle shut-off is observed. It is seen that higher volume flow rate in the nozzle increased the tank dome pressure during the refueling process. Pressure value set at the top of the tank as a rollover valve led to more air to flow out through the top of the tank when it had lower values. It is also observed that when gasoline droplet sealed the vent pipe entrance due to the rising fuel level or the back pressure developed in the tank, pressure reached to a peak value in the tank.