Study of multiple injections in (Homogeneous charge compression ignition) HCCI engine using computational fluid dynamics

Abstract

Due to the stringent emission norms, the research in the field of internal combustion engines in general and diesel engines in particular gathered huge importance and also increasing demand on fuel consumption the importance of detailed simulation of fuel injection, mixing and combustion have been increased in the recent years. In this research a CFD simulation is carried out on direct injection diesel engine to study the flow, combustion and emissions. In a diesel engine the flow pattern, that is, the turbulence inside the engine will control the combustion and thereby the emission mainly NOx, SOx and Soot. So it is very important to study the flow phenomenon first before the emission study is carried out. In this work an attempt is made to study the flow patterns for a cylinder design using split injection. Commercial CFD tool FLUENT is used for numerical simulation. It solves the basic governing equations of fluid flow that is continuity, momentum, species transport and energy equation. Using finite volume method Turbulence is modeled by using standard k-e model. Injection is modeled using Lagrangian system. The reaction is modeled using non–premixed combustion which considers the effects of turbulence and detailed chemical mechanism into account to model the reaction rates. The specific heats for all the species is approximated by using piecewise polynomials. In this research simulation has been carried out for triple injection and compared with experimental results and found that simulation results of triple injections have shown good agreement. Key words: Multi injection, pilot injection, triple injection, duration of injection, CFD.