Numerical Modeling of Flashing Sprays Using a Hybrid Breakup Model

Year 2018, Volume: 2 Issue: 3, 1 - 9, 30.09.2018

Yağmur Güleç Alvaro Dıez Francesco Contıno

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

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