Numerical Simulation Of Combustion Process Of Internal Combustion Engine

Since entering into the 21th century, designing the high-efficiency and low-emission engine has become the principal objective pursued by the scholars all over the world. To achieve this objective, a new concept on the engine combustion field was postulated and investigated extensively and deeply, which is Homogeneous Charge Compression Ignition (HCCI).In this dissertation, both numerical simulation program KIVA and chemical reaction kinetics software package CHEMKIN were combined and applied into theoretical simulation of HCCI. According to the computation, some valuable results were achieved that are the difference between HCCI and the conventional diesel engine combustion, the formation of homogeneous charge in cylinder, the features of heat release and NO emission. The primary efforts were focused on the influence of intake air temperature, compression ratio, EGR and power load on HCCI.It is proved that early injecting fuel into the cylinder at BTDC 50℃ A can perfectly produce homogeneous fuel-air mixture by analyzing the fuel and air density in the meshes at the period of the ignition. For HCCI, the engine demonstrates the high ratio of combustion pressure increase, which is much higher than the one of the conventional diesel engine , the phase of heat release during the 20℃ A BTDC and lower NO emission than diesel engine. With intake air temperature declining, compression ratio reducing and EGR ratio increasing, the combustion temperature and maximum pressure can be depressed down and NO emission can be reduced. While the power load is augmented gradually, the maximum pressure and the ratio of pressure increase are increased simultaneously. In the meantime, the combustion is inclined to be rough. At the conditions of high load, every measure for pursuing the low NO emission will result in the insufficiency of power output. For solving the problem, further research needs to be conducted.HCCI is absolutely different with conventional diesel engine combustion in nature. The significant factor for controlling HCCI combustion process is the chemical reaction kinetics of fuel. Presently, detailed chemical reaction kinetics mechanism has been the most promising research field.