Numerical Simulation Study On The Flow Field And Combustion Process Of Four-Valve Gasoline Engine

With the China's economic development,the industry of China is developing rapidly.Therefore,the investment in independent development and constantly optimize of IC engine should be increased,so as to reduce labor costs and environmental pressure.As the development of computer technology and computational mathematics,numerical simulation has been able to replace part of the experimental with long cycle and high cost,and some parameters that can't be obtained by simulation are also obtained.The aim of this paper is to improve the engine performance,the influence of flow field and advance angle of ignition on combustion in cylinder is studied based on four-valve gasoline engine,the software CONVERGE was used to for this work.The three equations of fluid mechanics are discussed in detail.The turbulence model,combustion model,chemical kinetic model,numerical calculation formula and calculation strategy used in the software are introduced.A block diagram of the order of transport equation is drawn.The modeling of the fluid domain surrounded by structures such as intake port,exhaust port,valve and combustion chamber were done by CATIA,a 3D modeling software.The model was imported into the software to complete the generation of the surface grid and the division of different boundaries and regions.Then the compression ratio of the model was adjusted.The setting of the body grid division of the model should be done,and the grid should be encrypted according to the function and shape of each different position.Finally,complete the setting of boundary conditions and initial conditions for the simulation.The visual processing of flow field simulation results in intake port and cylinder was done,and the flow field cloud map,vector diagram and particle trace diagram of the intake port and cylinder were obtained.Based on the results,the development of the flow field distribution,eddy current and rolling flow in the intake port and cylinder with the development of throttle opening were analyzed.The turbulent kinetic energy in the cylinder of 3000r/min was studied,and it was compared with the different revolving speed of 4000r/min and 5000r/min.Furthermore,the influence of different ignition timing angles at different revolving speeds of 3000r/min,4000r/min and 5000r/min on the turbulence kinetic energy of the cylinder after ignition was analyzed.In order to analyze the combustion performance of the intake port injection engine,the combustion performance of the ideal mixture was simulated,and the combustion performance of the intake port injection engine was compared with that.Furthermore,respectively to the speed of 3000r/min,air-fuel ratio of 14.7 and the speed of 4000r/min,air-fuel ratio of 16 and the speed of 5000r/min,air-fuel ratio of 13,under the condition of the research on the effects of different advance angle of ignition on the combustion performance,and the more reasonable advance angle of ignition was found out.