Cyclone Large Eddy Simulation And Separation Performance

Cyclone separator is a kind of equipment that uses rotary motion of gas-solid two- phase fluid to make the solid particle separated from the gas flow by centrifugal force. Because of their simplicity, easiness and low costs in terms of construction, operation, maintenance and energy consumption. It is necessary to make deep research for the flow field and the influencing factors of cyclone separators, and has important significance in improving performance of cyclone separators.Firstly, the domestic and overseas research actuality of cyclone separators is expounded, and the problems in the research of cyclone separators are pointed out, and numerical simulation is very necessary. By accessing and studying a lot of literature of numerical study of gas-solid flow in cyclone separators, this thesis uses LES model to simulate gas field, and uses the two-phase fluid coupling of Discrete Phase Model (DPM) in the Lagrange-coordinate to simulate distribution and the rule of the inner solid phase of cyclone separators.By pre processing software Gambit, an axial flow cyclone separator, 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. By software Fluent, based on the anisotropy of LES model for turbulent flow, QUICK format for difference scheme, RESTO format for pressure discrimination and SIMPLEC arithmetic for pressure-velocity coupling, simulate the gas field in the cyclone separators. The velocity field, including tangential velocity, axial velocity and radial velocity, and the pressure field, including static pressure, dynamic pressure and the total pressure, are studied systematically.Take the data of simulation compared to the experiment data in the Reference, and make sure the simulation is right.For the numerical study of gas-solid flow in cyclone separators, this thesis uses the two-phase fluid coupling of Discrete Phase Model (DPM) in the Lagrange-coordinate to simulate distribution and the rule of the inner solid phase of cyclone separators. The separation efficiency of the cyclone separator was simulated, considering different particulate diameters, particulate injection velocities, particulate concentration, outlet pipe diameters, insert depth of outlet pipe and so on. The moving tracks of particles were also obtained in some conditions using the software in this thesis. The results show that, separation efficiency is different in different conditions. The experiment results indicate the efficiency of cyclone separators is higher and the influence of different particulate concentration and different velocity are consistent with the numerical simulation.