Study On Combustion Process And Chamber Improvement Of CA6DL1-30 Diesel Engine

Diesel engine with high thermal efficiency,low fuel consumption,good dynamic performance and good economy,has been widely used in truck,motorcycle,marine and electric power generation.However,the effect of emission(NO and Soot) on the environment has become increasingly serious,so it is very important to optimize the combustion process of diesel engine to reduce harmful diesel emissions and improve the performance of diesel engines.The traditional test method can only provide limited information,but multi-dimensional numerical simulation can get the results which is difficult to obtain in the experiment.And it also has other advantages,such as low cost, short cycle.The multi-dimensional numerical modeling of diesel engine combustion process is introduced in this paper.The turbulence models,diesel spray models,combustion models and emission models are explained in detail.The combustion process of CA6DL1-30 diesel engine is simulated with aid of CFD software STAR-CD.Gas flow field, inflammable mixture distribution,temperature distribution,pressure distribution and emissions distribution are displayed detailedly.Through comparing with experimental results,calculation models are proved to be validity.On this basis,the effects of different fuel injection advance angle and different combustion chamber shape on combustion and emissions performance of diesel engine are calculated and analyzed.The results show that:1.Fuel injection advance angle affects the formation of mixed gas in cylinder and the combustion process of diesel engine.Due to increase fuel injection advance angle,extend ignition delay period,the period for the formation of the pre-combustion gas mixture will prolong,and the largest outbreak of cylinder pressure and the maximum combustion temperature will increase.The emission of NO increased as the temperature increased. However,the emission of soot reduced resulted from the fuel injection advance angle increases,the mixed quality of oil and gas in cylinder improved.Therefore,it will be helpful for reducing soot emissions to increased fuel injection advance angle.2.The shape of combustion chamber changed the characteristic of flow field in cylinder,which affects the formation of mixed gas and determines the different combustion characteristics.Neck diameter affects the strength of the initial combustion compression squeeze flow,thus affecting the initial quality of the mixture in cylinder.The central boss affects the air movement in cylinder in the expansion stroke,thus affecting the intensity of the late diffusion combustion.NO and Soot emissions are very different in the different combustion chambers.After the study of this paper,we can find the useful method to update design and optimize performance of the CA6DL1-30 diesel engine.