Special Combustion Chamber in the Cylinder of Diesel Engine Working Process Simulation Analysis Based on the FIRE Software

摘要

Exhaust noise is the main component of vehicle noise in the study of vehicle noise controlling. It is important to design a type of muffler that can match to engine and have the capability to reduce vehicle noise. At present vehicle mufflers are made by examination, therefore the time of product development is very long and it wastes material. Sometimes exhaust noise can not be reduced; in the contrary it will decrease the power of engine. The content of exhaust noise is tightly related to the temperature, pressure and velocity of combustion gas. In order to obtain the detail data of these parameters, FIRE software is used to perform the calculation of engine combustion process in this paper. FIRE is one of the advanced 3D simulation software packages and can simulate the complicated gas flowing and combustion in internal combustion engine cylinder. Its calculation result accesses to the fact and can attain gas temperature, gas pressure and gas velocity, provide reliable original data for the design of a muffler. In this paper, the basic combustion theory of internal combustion engine is introduced to the basis for the further application of numerical simulation, firstly. The geometrical model and mesh model of a type internal combustion engine are constructed by using FIRE software to analyze the working process of internal combustion engine. Based on the model and combustion theory, the relevant calculation model and initial parameters are chosen and applied into the software. A load case is designed according to the true running process of this engine. With these load cases, the combustion process is simulated in this paper. The detail distribution of the parameters such as combusted gas pressure, combusted gas temperature and velocity of the flow fields in cylinder is obtained and the relation of these parameters and crankshaft angle is given for the further research. It also provides data for muffler design by boundary element method. It is obvious that can shorten the product developing cycle and save the material.