Lube Oil Soot Reduction Using Combustion Simulation for CPCB2 Compliant Cummins N14 Engine

A combustion system has been optimized for the Cummins N14 diesel engine using KIVA-RIF to meet CPCB2 emission norms. It has been developed to reduce lube oil soot while meeting the legislative requirements for PM and NOx. The optimization involves closed cycle combustion simulation at three operating conditions: 110%, 75% & 50% load at rated speed. A combustion CFD code, KIVA-RIF has been calibrated to simulate the experimental results at all these points. Qualitative comparison has been done between soot on liner from simulation to lube oil soot from experiments. Parameters studied during combustion simulation involved the study of piston bowl profile, injector configuration (number of holes, spray angle, and through flow), injection timing and swirl. From combustion simulation, a deep spray angle bowl has been observed as a promising solution due to improved emissions and lube oil soot. The combustion recipe identified has a characteristic PM vs NOx curve for injection timing swing. Validation of simulation results with engine testing in terms of PM, NOx, and lube oil soot has been observed in good agreement.