Three-Dimensional Computational Fluid Dynamics Modeling of the Combustion Process of a MAN L21/31 Marine Diesel Engine

In the available literature, information on marine engines is limited for the general researcher. The goal of this study is to provide high quality information on a marine diesel engine that is beneficial to the engine community. Information on a 6L MAN L21/31 marine diesel engine is collected from existing studies and a three dimensional computational fluid dynamics model is built in this paper that can characterize the in-cylinder activities occurring in this marine engine. The good agreement between experimentally measured and model predicted cylinder pressure and heat release rate indicates a good calibration of the numerical model. Simulation results show that sufficient oxygen is still available in the chamber when the exhaust valve is open, suggesting the possibility of further reducing incomplete combustion products by increasing the utilization of excess air. Moreover, the model predictions help to show that the injection settings are already well calibrated for the rated power condition in terms of the balance between fuel economy and clean combustion. Accordingly, future efficiency improvements and emission reductions are suggested to be achieved by the optimization of the chamber shape, which has the potential to further improve the air utilization.