عنوان مقاله [English]
In this article, the effect of increasing turbulence intensity and changing fuel injection angle on performance and pollution of Caterpillar marine diesel engine has been investigated using computational fluid dynamics method in Fire software. To this end, two phase flow inside the diesel injector was simulated using the CFD.Solidworks software has been used for geometry creation and AVL-Fire software has been used for meshing and simulating. In order to increase the turbulence intensity, the groove inside the injector nozzle has been used and the fuel injection angle has been increased. Numerical results of injector and diesel engine simulation in operating conditions were compared with experimental data and a good agreement was observed between them. The results of diesel engine performance show that grooving, increasing turbulence intensity and fuel injection angle lead to a 75% increase in power and torque output and a 37% reduction in fuel consumption compared to the cylindrical fuel nozzle. Also, the results related to the pollution of this marine diesel engine show that in this case, the pollutants of carbon monoxide and nitrogen oxide decreasing 42.73% and 45.45%, respectively. Also, in this case, the engine has no problem in terms of producing soot pollutants and the soot produced during the combustion process is well oxidized. Then, in order to create a rotational flow and reduce the intensity of cavitation as well as the resulting erosion, the geometry of the cylindrical nozzle hole was changed to a converging cone and the groove inside it was used. The numerical results show that changing the geometry of the nozzle hole and creating a rotational flow inside it leads to reducing the severity of cavitation and thus reducing the erosion and corrosion caused by it and increasing the life of the injector nozzle. Thus the fuel spray characteristics can be controlled by creation of swirly flow and changing the nozzle geometry and needle lift profile. Numerical results and experimental data validated from previous researches.