Numerical Simulation Of Combustion Of Emulsified Heavy Oil In Diesel Engine

The problems of energy crisis and emission pollution are increasingly concerned by governments and research institutions of all over the world. Improvement of fuel economy and reduction of harmful emissions are becoming the focus of the engine research. Thanks to the advantages of higher fuel economy and lower harmful emissions, emulsified heavy oil is considered as a promising alternative fuel. Normally, in the study on the emulsified fuel, combustion test takes most part of research resources and time. Numerical simulation can substitute part of test, guide the test and reduce research times, so the accurate and effective numerical simulation is very important.In this paper, the numerical simulation methods of engine combustion process are introduced; the gas phase turbulence flow model, the fuel spray model, the turbulence combustion model and the combustion chemistry dynamic model are analyzed. After adding complete heavy oil physical parameters to the KIVA fuel database, through developing programs, the physical parameters of the different water ratio emulsified heavy oil were calculated. According to the characteristics of emulsified oil, its breakup submodel was modified. With the application of the modified program, the spray process and the combustion process of a 135 type single cylinder diesel engine were simulated. The influence of water mixing ratio, injection advance angle, numbers of injection holes and load rate on engine were analyzed. Through the analysis of temperature fields, cylinder pressure curves, and NOx mass fraction curves, the combustion process and emission performance were evaluated. The comparison of simulation and test results confirms the correctness and validity of the modification on the breakup model of the KIVA program.