The Simulation Research Of The Air Intake System’s Effects On 4190Z_LC Diesel Engine’s Performances

The development of industrial technology brings the industrial civilization to us, but deteriorates the environment of our earth at the same time; nowadays people are becoming more and more aware of the importance of economy and environmental protection. Developing more friendly technology for environment becomes the society-wide consensus currently, and these technologies include the development of new energy, and the reforming of the old equipment. Before the new energy is fully developed, reforming the old equipment is an effective way. Based on the above reasons, Institute of Marine engineering decided to reform the fuel oil system by electrical control for 4190 ZLC diesel engine in the lab, so as to improve its economy and emission.Because of the sharp increase of the fuel oil supply pressure after reformed, the combustion organzation of the diesel engine have been changed greatly. The air intake system is the another main factor that determines the combustion performance. How to reform the air intake system to match the reformed fuel oil system is one of the keys to guarantee the machine performance, so it is necessary to research on the air intake system of the original machine.This paper builds the surface model of intakeport by the reverse modeling method; materializes the model, and sets up and assembles the inlet valves and its seats submodels and combustion chamber by Pro/E software; and the steady state and transient simulation research works have been done by AVL_FIRE software.Firstly, the swirl ratios and flow coefficients for different valve lifts obtained from the steady state simulation of the intakeport agree with the experimental results of the steady flow test bench very well; it implies that the air intakeport model is correct. The analysis of three-dimensional flow field of the steady state simulation shows that there are unreasonable flows in the local areas of long airway and the areas near the valve seat, so the shapes of these areas need to be optimized.Secondly, the average parameters in cylinder at the different engine speed are obtained by the transient simulation of the intake process; the results show that: the quicker the engine speed, the more the cylinder air mass and the later crank angle the maximum cylinder air mass moments correspond to; this means that the intake valve close angle should be different at different engine speed; so the intake valve close angle can also be a part of something need optimized for 4190 ZLC diesel engine.Finally, the influence on the economy efficiency and emissions of the inlet air pressure, and temperature have been studied by the transient simulation of the intake, compression and combustion process. The results show that: with the lower the inlet air temperature and the higher inlet air pressure, the incoming air mass in cylinder will be more, the better mixture of the fuel and the gas air can be obtained and the SOOT and NOx emissions of the engine decrease, these help to improve the economic efficiency and to reduce emissions of diesel engine.The research in this paper, lays the relevant theoretic foundation for the performance improvement of 4190 ZLC diesel engine.