Spray evolution in small bore d.i. Diesel engines with different injection strategies.

Engine downsizing is one of the most promising alternatives to improve fuel economy, while maintaining good emissions and NVH behavior. In this paper the spray evolution in a small combustion chamber, adopting different injection strategies (pilot-main and pre-main), are analysed by means of experiments and numerical simulations. To this aim an optical research engine with the combustion chamber size of a small (0.3L) DI diesel engine was employed. Multidimensional simulations were performed with KIVA3V code. Once assessed the code predictivity in the case of different injection strategies, numerical results are validated comparing spray evolution and wall impact with optical engine visualizations.