The model of the exhaust gas duct flow of the marine 4-stroke diesel engine

The manuscript presents the model of the exhaust gas flow through the exhaust gas duct of the marine 4-stroke engine. Presented model are computational fluid dynamic model based on dimensions and the construction of the real exhaust gas duct. The measurement parameters from real object are used to the model validation. The simulation of the exhaust gas duct throttling by rotational throttling plate was done. Obtained calculation results allow to determination of the exhaust gas mass flow for the simulated flow characteristics. The model of turbulence flow was taken into account. The gravity forces and the heat transfer phenomena were neglected. Obtained calculation results are qualitatively consistent with results obtained from literature. The analyze of the velocity distribution in the exhaust gas duct allows to conclusion that the changes of the angular position of the throttling plate causes significant disturbances in the exhaust gas flow. The result of this is the decrease of the exhaust gas flow. Additional purpose of the manuscript was approximation of the obtained results of the exhaust gas flow for different angular positions of the throttling plate. Obtained polynomial function may be useful tool to modeling the combustion process in the engine cylinders for the different flow characteristics of the exhaust gas duct. The calculation results allow to determination the mass flow of the exhaust gas with mean error equal 11%.