Study Of The Fuel Distribution Of Diesel Under Low Temperature Premixed Combustion Mode

In recent years development has been made in new combustion theoryand technology, in which the combustion mode represented by the LTC(low temperature combustion) has got in-depth research. It abandoned thecharacteristics of flame propagation under diffusion combustion andreduced emissions by utilizing premixed gas mixture, compression ignitionand low temperature mode.The low temperature and premixed combustion mode leads to asignificant reduction in the emissions of NOx and PM at the same time.However, the uHC increases significantly simultaneously, which causesthe decrease of combustion efficiency. Previous studies have shown thatthe spatial distribution of the mixture in cylinder had a profound effect onthe uHC emissions. The over low or high concentration together with thewall film and gap area were the feature regions which mainly results inemissions.The paper focus on the research of premixing process of Diesel gasmixture, specializing in the test methods, study of its influential factors aswell as the controlling modulation for the distribution of the mixture.Relying on the experimental test and numerical simulation methods,multi-pulse injection was investigated in order to understand that theconfiguration could be optimized to create optimum mixture formationconditions for Diesel combustion, which could avoid the generation offeature region.Diesel injection tests were carried out after the experiment platform had been established. Also a corresponding CFD simulation model was setup and mixture formation process was calculated under differentconditions for the single to multi-stage injection strategy. The injectionparameters’ influence on the shape and penetration of oil beam wasanalyzed, the coupling effect of injection number and dwell time to themixture formation was acquired as well. The CFD model using movinggrid verified the improvement effect on the concentration distribution incylinder under the presence of air movement and compression processconditions in the end.Results showed that the characteristics of Diesel mixture distributionwas highly sensitive to the multi-pulse injection strategy under lowtemperature premixed combustion mode. It was important to set reasonableparameters which matches the actual environmental condition in cylinderso as to improve combustion efficiency and reduce uHC emissions.