| In recent years, pollutant emission from motor vehicles has been one of the major air pollution problems, especially the particulate emission. The particles are responsible for health problems due do their fine size and toxic compositions. As one of the effective diesel engine exhaust after-treatment technology, the cyclone separation becomes more and more important. It is necessary to make deep research for the performance and the influencing factors of cyclone separators.An axial flow cyclone, with a tangential inlet, was created in this thesis. The simulation domain and boundary conditions were specified according to the exhaust characteristics of a diesel engine, and then the proper computational grid was exported. The RNG k-εeddy dissipation model was used for the numerical simulation of the flow field of the cyclone separator. The velocity field,including tangential velocity, axial velocity and radial velocity,and the pressure field in the cyclone separator were simulated,considering the factors of different operating temperatures, different inlet gas velocities, and different outlet pipe diameters, etc. Moreover, in view of the effects of unsteady gas inlet velocity, some research had been done to predict the flow field in the cyclone separator.Based on the relative references and research findings, the motion rules and distributions of the particulates were simulated with commercial software FLUENT after some hypothesis and simplification in the Lagrange-coordinate. The separation efficiency of the cyclone separator was simulated, considering different particulate diameters, particulate injection velocities, gas temperatures and outlet pipe diameters and so on. The moving tracks of particles were also obtained in some conditions using the software in this thesis. The results show that, collection efficiency is different in different conditions.The results of this paper can be valuable data for study and development of emission control regulations. |
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