Analysis of Spray Feature Injected by Tailpipe Injector for Aftertreatment of Diesel Engine Emissions 2017-01-2373

Diesel Particulate Filter (DPF) is a very effective aftertreatment device to limit particulate emissions from diesel engines. As the amount of soot collected in the DPF increases, the pressure loss increases. Therefore, DPF regeneration needs to be performed. Injected fuel into the exhaust line upstream of the Diesel Oxidation Catalyst (DOC), hydrocarbons are oxidized on the DOC, which increases the exhaust gas temperature at the DPF inlet. It is also necessary that the injected fuel is completely vaporized before entering the DOC, and uniformly mixed with the exhaust gases in order to make the DOC work efficiency. However, ensuring complete evaporation and an optimum mixture distribution in the exhaust line are challenging. Therefore, it is important that the fuel spray feature is grasped to perform DPF regeneration effectively. The purpose of this study is the constructing a simulation model. The secondary fuel injection is classified into free spray, impingement spray, evaporation of liquid-film, and HC concentration distribution. So it is difficult to predict phenomena because each phenomenon is complicatedly involved. Therefore, it is necessary that each phenomenon is evaluated in basic experiment. This report focuses on impingement spray on the wall under high temperature field by LIEF and LIF method and spray under the flow field by scattered light method and compares experimental results with numerical analysis results. As a result, it is clarified that the gas phase due to fuel evaporation has a distribution near the wall when P_inj is 1MPa under high temperature field. On the other hand, the gas phase is widely distributed when P_inj is 4MPa because droplets are involved in the vortex. Also, it is clarified that swirl spray does not form follow up spray under the flow field because droplets are given momentum by flow.