SC1-1: Experimental Evaluation of Spray Dynamics and Its Evaporation Generated by Diesel Twin Jet Injection Nozzle(SC: Spray and Spray Combustion,General Session Papers)

Abstract

Aiming to further improve Diesel engine fuel efficiency and exhaust emissions, we conducted evaluation of a newly devised Twin Jet Injection (TJI) Diesel fuel system, where two jets were formed separately and then interacted into the nozzle exit hole. l ransmission and Schlieren photography and phase-Doppler anemometry were used to quantity transient spray and evaporation dynamics. The nozzle produces a nearly homogeneous fuel spray with wider cone patterns up to 68℃ and finer droplet sizes less than 22 microns. The concentration of fuel droplets into the spray is two orders of magnitude lower vs. conventional Diesel highly stratified jets. The TJI spray pattern results in higher mixing and rapid evaporation that minimizes the soot and NO_x emissions inside the engine cylinder. Ideally, to achieve better control of compression ignition (CI) combustion at high speed and load the fuel system needs an injector that provides homogeneous fuel distribution. An extended Diesel homogeneous-charge CI (HCCI) also requires totally vaporized fuel prior to the combustion reactions. A homogeneous fuel-air mixture is one in which the composition and the thermodynamic conditions are uniform throughout the reaction phase. The CI- and HCCI-combustion efficiency is mainly controlled by injection, i.e. its timing and rate-shape. The TJI fuel injection technology allows converting highly-stratified injection spray into a nearly homogeneous injection.