Characteristics of gasoline flash boiling atomization triggered by iso-pentane blends at different ratio

Abstract

Flash boiling spray can improve fuel atomization efficiency via fierce phase change of the fuels both inside and outside the nozzle. Typically, active flash boiling atomization is achieved by heating the fuel before injection, which would require additional energy for heating and more complex fuel temperature controls. Another approach to enable flash boiling atomization is to dope fuels with low boiling points into regular fuels. However, the atomization and combustion mechanisms of adding low boiling point fuels are not fully revealed yet. This investigation aims to study the effect of mixing a low boiling point fuel (iso-pentane) with regular gasoline fuels. The fuel temperature is controlled so that flash boiling of iso-pentane is triggered while gasoline is still under its sub-cooled conditions. The iso-pentane volume fractions of 0%, 40%, and 80% bent with RON 95 gasoline were tested in this study. Microscopic analysis was made to understand the near-field breakup characteristics using different fuel combinations. It is found that the blends of iso-pentane could significantly enhance the atomization process due to a combination effect of flash boiling and evaporation, while flash boiling tends to extend the spray width, resulting in better fuel-air mixing and a more homogenous mixture.

Keywords

• GDI engine
• Flash boiling spray
• Fuel design
• Optical diagnostics