Macroscopic characteristics of flash-boiling spray focused on plume interaction

Abstract

In gasoline direct injection (GDI) engines, plume-plume interaction usually occurs when the superheated fluid discharges from multi-hole injectors. To mitigate plume interaction for further utilizing the merits of flash-boiling phenomena, it is essential to obtain the criteria of plume interaction and their effects on flashing spray characteristics. An 8-hole injector from Engine Combustion Network (ECN) is used to obtain the plume interaction criteria. Iso-octane, pentane, hexane, and their blends were tested, and experiments using the method of diffused back illumination (DBI) were conducted in a constant volume chamber (CVC). The new nominal parameter calculated by the pressure-enthalpy graph was introduced to analyze the spray morphologies and macroscopic characteristics. The new criteria considering fuel properties, injector geometries, and ambient pressure were obtained and validated by mono- /multi-component fuels. Based on the new criteria, spray characteristics in various stages of plume interaction are investigated. The tunning point of tip penetration and spray angles occur at the critical point defined by the new criteria in all tested fuels.