Experimental and Numerical Validation of In-Cylinder Combustion Analysis of DI Diesel Engine

Abstract

The major factors affecting the process of combustion in a single cylinder diesel engine is in-cylinder fluid flow characteristics. Better fuel-air mixing and combustion rates in diesel engine are primarily enhanced by the fluid flow. The fluid flow prior to combustion process in DI diesel engines travel through induction process and further gets improvised during the compression process. Therefore, it is compulsory to understand the fluid flow motion inside the cylinder in designing the different bowl-in-piston geometries with the most appropriate operating and emission characteristics. A better spatial distribution is required for the injected fuel throughout the entire space of combustion geometry in DI diesel engine, to obtain a better combustion with lesser emission. In order to effectively make use of gas flows it is mandatory to match the piston bowl geometry with fuel spray characteristics. For obtaining better combustion, matching of combustion chamber geometry, fuel injection and gas flows plays prominent role. But it is evident that piston bowl geometry plays a significant role on flow of compressed air when piston moves from BDC to TDC i.e., before the start of combustion, resulting in proper mixing, better vaporization and atomization of fluid particles. When compared with other combustion chambers, Off-set bowl in the absence of central projection with sharp edges provide higher swirl number. Higher these whirl number lesser will be the soot emission at the expense of higher NOx level.