Analysis on Three Dimensional Flow of Direct-injection Diesel Engine for Different Piston Configuration using CFD

Recent years have witnessed rapid developments in the field of IC engines. Today both the manufacturers and the customers are looking for low polluting and better efficient engines. Basically, the in-cylinder gas motion affects the performance of the engine. Increase in combustion efficiency obviously results in fuel economy and low pollutant emissions. So, it is necessary to have a better control over in-cylinder gas motion. The main objective of this project is three dimensional flow calculations of the compression stroke of a four-valve direct-injection Diesel engine for different Piston configuration. A limited number of validation calculations of the Intake stroke and compression stroke were performed in order to explore the limits of Computational Fluid Dynamics representation of the in-cylinder flow. In the main study, the flow characteristics such as Swirl Ratio, Radial Velocity field and Tangential Velocity field inside the engine cylinder equipped with different piston configurations were analyzed in detail. The results confirmed that the piston geometry had little influence on the in-cylinder flow during the Intake stroke and the first part of Compression stroke. The bowl shape plays a significant role near TDC and in the early stage of the expansion stroke by controlling the turbulence velocity fields.