This study includes numerical analysis of diesel engine with different bowl geometry. 3D CFD analyzes of the engine with asymmetrical piston geometry were performed in Ansys Forte software. In the study, a single-cylinder, four-stroke and direct injection diesel engine was used. It has been tested where the maximum torque is obtained as the operating condition at 2000 rpm. According to the results obtained from the analyzes, the new combustion chamber system (NCCS) geometry provided a 40.3% reduction in soot emissions while NO emissions increased slightly with the 8-cavity bowl geometry created in the combustion chamber compared to the standard combustion chamber system (SCCS). Increasing air velocity and turbulent kinetic energy (TKE) values in the combustion chamber affected the evaporation levels of the fuels. As a result, the improved mixture formation caused a decrease in incomplete combustion products (CO, HC and soot). The NCCS geometry according to SCCS type, an increase of approximately 4.2% occurred in the calculated squish rates. It has been observed that the increase in the bowl surface area causes the combustion and thus the temperature to spread over a larger area on the piston.

This paper has included the effects of different bowl geometries which has the wall guided fuel injection. Bowl geometries, which affect in-cylinder air flows, have a great influence on the change of mixture formation. Also, the region where the fuel hits in the bowl affects all engine parameters. In this presented numeric study, the standard combustion chamber geometry of a single-cylinder, air-cooled, and direct-injection diesel engine is compared with the designed new combustion chamber. Four different rotation angles (0°, 7.5°, 10°, and 15°) were determined for the new combustion chamber geometry and compared with the standard geometry. The three-dimensionally modeled bowl geometries in 3D Computational Fluid Dynamics simulation were examined in terms of in-cylinder pressure and temperature, instantaneous and cumulative heat release rate, exhaust emissions (NO, soot, CO, and CO2), temperature/spray, and equivalence ratio/spray at different CA’s. The effects of the different rotation angles of the designed new bowl geometry on both the air movement and the region where the fuel hits were investigated for the engine parameters. When the results obtained are examined, maximum in-cylinder pressures for standard combustion chamber, new combustion chamber 1, new combustion chamber 2, new combustion chamber 3, and new combustion chamber 4 geometries were obtained 79.5, 75.2, 78, 78.1, and 78 bar respectively, and the maximum in-cylinder temperatures were found 1766, 1742, 1805, 1817, and 1818 K, respectively. According to the results obtained from the numerical analysis, CO, CO2, and soot emissions decreased while NO emissions increased in the new combustion chamber, compared to the standard combustion chamber. Examined the spray distributions in bowl, it was seen that the fuel sprays distributed more homogeneously and flame propagates which is spread throughout the chamber in the new combustion chamber type, which improved the mixture formation. The wall guided fuel flow in the novel designed chamber geometries beneficial to turbulence kinetic energy, spray distribution, emissions.