Numerical Modeling of Flashing Sprays Using a Hybrid Breakup Model

Abstract

Fuel droplets may undergo flash-boiling conditions when they are injected into a cylinder at higher than saturation temperature for the corresponding chamber pressure, resulting in a rapid evaporation. Such conditions lead to wider spray angles, finer droplets and shorter penetration. Based on current experimental investigations, such conditions may promote a more homogeneous fuel-air mixture and a faster evaporation compared to traditional methods.

This investigation presents a numerical study in OpenFOAM focusing on the modeling of gasoline direct injection sprays under flash and non-flash boiling conditions. The model was implemented in a scenario where already superheated and compressed fuel at 100 bar was injected into a chamber at a pressure lower than its saturation pressure at the corresponding temperature. A new hybrid breakup method has been implemented along with a momentum flux post-processing tool for the characterization of the initials conditions.

It was found that better prediction accuracy in evaporation rate was obtained. Spray penetration was also better modeled for flash boiling conditions compared with traditional breakup models.

Keywords

• spray,momentum flux,cfd

References

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