抄録
In order to achieve the clean exhaust emissions and the high fuel efficiency in a diesel engine, it is necessary to optimize the mixture formation and the combustion processes. A combustion chamber shape is one of the dominant factor among the many factors in determining the combustion characteristic. In this study, a new concept of combustion chamber shape, an Egg-shape combustion chamber was proposed. For the first step, to examine its effectiveness on the mixture formation, the combustion process and the exhaust emissions, numerical simulations by Computational Fluid Dynamics were carried out under the engine operating condition. Secondly, to clarify the behavior of fuel spray and the combustion characteristics, the experimental measurements by means of Laser Absorption Scattering method and Two-color method were carried out under the conditions of wall-impinging spray and combustion with constant-volume vessel. Through the numerical simulations and the experimental measurements, it was clarified that Egg-shape combustion chamber concept is very effective to enhance the in-cylinder gas mixing and to reduce the exhaust emissions. Finally, this Egg-shape combustion chamber concept was proven as effective in improving the exhaust emissions and the fuel efficiency by the engine experiments.
