The Research On Flow Field In Ports And Cylinde Of Four-valve Gasoline Engine For Automobile

With the strictness of national emission law, traditional dual-valve gasoline engine is trending to disappear and multi-valve gasoline engine with electric fuel injected system become the backbone of automobile engine. The airflow condition in multi-valve gasoline engine has great influence on mixture combustion speed, and then affect the performance of power, economy and emission.The 2.4L multi-valve gasoline engine developed by the third research laboratory of Tianjin Internal Combustion Research Institute was investigated in this paper. Firstly, the four-valve configration in each cylinder was adopted by researching the relationship between the valve number and the geometrical pass section area. On the basic of analysis of main engine parameters, which affects airflow field, we chose large angle pentroof combustion chamber to get higher volumetric efficiency. The optimum port and combustion chamber was used to form effective airflow in the cylinder and made the propagation speed of onflow flame accelerated.Secondly, on the analysis of many references the RNG-εturbulence model, the finite volume method and non structural grids with partial denseness technique and more accurate boundary condition were adopted to improve simulation calculation precision.Thirdly, the comparison between simulation in stable condition and experiment on port the result showed both of A and B ports had high flow coefficient and the maximum error between simulation and experiment was less than 7%. It validated the precision of simulation calculation.Fourthly, after making use of moving-grid generation technology and comparing transient stimulation analysis results on Ⅰ,Ⅱ,Ⅲ projects, it was found that in project Ⅲ with B port could produce two inclined-axed whirl with small angle, in which the tumble played the main role and kept until compressed TDC. The investigation on turbo kinetic energy field in project Ⅲ showed that before the ignition not only relatively large turbo kinetic energy was kept ,but also the location of turbo kinetic energy zone was better, which were good to accelerate the flame core formation during the ignition delaying and speed up the flame spread speed during quick combustion process. As the result, the project Ⅲ was the optimum choice. The experiment data of test engine and vehicle emission with project Ⅲ showed that the performances of power and emission reached the expectant target. In the research on flow field in ports and cylinder of four-valve gasoline engine for automobile, a virtual design method was adopted, which makes use of simulation in stable and transient condition and combined with experiment. It could obtain much information in short time and provide reliable theoretical evidences for related structure design of engine.