The Analysis And Experimental Study Of The Engine Intake System Based On CFD

The engine intake manifold and intake port are important components of theengine air intake system. The performance of the system will directly influence theformation of the inflammable mixture and the spread of the combustion flame in thecylinder. Therefore, an excellent engine need to design good engine intake manifold andintake port.In the traditional design process of air intake system, it mainly rely on the personalexperience and the steady flow experiment, but this method need long time and highcost. Therefore, the CFD method is used to analyse the flow field of the engine intakesystem to provide the basis for the design and improvement of the structure of the airintake system. The air flow in the intake manifold and intake port was calculated in thethesis by using the fluid analysis software STAR-CCM+. Firstly, a90°T-junction modelwas used to validate the effection of the grid model, the boundary layer and thedirection of the template on the calculated results, it provides the basis for meshing inthe simulate calculation process. Secondly, three-dimensional geometric model of twoengines’ intake manifold was established and simulated, then further analysis about theflow field and pressure loss was done and the difference of the mass flow rate betweenthe simulation and the experiment was compared. Finally, three-dimensional geometricmodel of engine’s intake port was established and simulated, then the distribution of thepressure, velocity and turbulent kinetic energy was analysed. Also, the mass flow rateand swirl ratio data was obtained and compared with the experimental results to verifythe accuracy of the simulation.The results of the study showed that: In the process of the CFD simulation,different grid shapes, boundary layers and the direction of the template will effect thecalculation results, the positive hexahedral grid, two boundary layer grid mesh could beconverged faster and get higher calculation accuracy; through the calculation of theintake manifold, we found that the calculation results can fully reflect the information ofthe flow field in the manifold, the pressure and the velocity change fiercely in the portbetween the entrance and the pressure stabilizing cavity and the port between thepressure stabilizing cavity and the branch pipe. The result complied with the basictheory of fluid mechanics. Compared the results of the calculation and the experiments,we found some deviation. The main reason is the accuracy of the experimentalequipment and the difference between the calculation model and the experimentalmodel. Analysed the result of the CFD simulation of the intake port and compared theswirl ratio between the simulation and the experiment, we found that the deviation was less than five percent. We fully verified the reliability of the CFD simulation.The accuracy of the CFD calculation was verified in the thesis through thecomparison of the CFD simulation and the steady flow experiment of the intake system.A quick and effective research method for the design and structure improvement of theintake system is proposed in the thesis.