Research And Numerical Simulation Of Gas-solid Flows Of Electrostatic Cyclone

For electrostatic cyclone of installing electrode in the center,a three-dimensional numerical model including fluid flow,corona discharge,particle charging and particle motion was established.The model of corona field and the effects of ion after ionization on the flow field and particle motion,were introduced through the UDF programming interface.As for airflow.Fluid flow was solved using the time-averaged Navier-Stokes equation.Reynolds stress in flow field was calculated based on anisotropic Reynolds stress transport equation.The pressure-strain term and dissipation term in the Reynolds stress transport equation were modeled according to linear pressure-strain model and the standard 6) model.Near-wall treatments for wall-bounded turbulent flows using standard wall functions.Using the control volume method to discretize the model,and applying the SIMPLEC algorithm to compute the flow field.As for particles movement.Particle motion was calculated using the Euler-Lagrangian method.Particle charging used saturated charge of electric field.Turbulence dispersion of particle was calculated by the particle cloud model.Obtained that the distributions of electric potential,electric field and current density.Analyzed the contour lines of velocity field,pressure field,and turbulent energy with the certain corona voltages,flow rates,and lengths of exhaust pipe.Simulated the trajectory of particles and computed particles collection efficiency in different regions with the certain corona voltage,flow velocity and insertion length of exhaust pipe.Summarized the results of airflow simulation.With the higher corona voltage,the increase of axial velocity and tangential velocity becomes larger during the upward of the cone,and the effect of corona voltage on tangential velocity is greater than the axial velocity.As the faster air velocity,the intensity of the vortex becomes more intense in the cone,and the backflow area becomes bigger near the electrode.The shorter insertion length of the exhaust pipe,the process of upswing flow presents a tortuous path,and the average axial velocity and tangential velocity of the upward decrease.Applying higher corona voltage,faster airflow and shorter insertion length of the exhaust pipe,will result in increased total pressure and flow loss.But the loss caused by airflow is great.Summarized the results of particles movement simulation.In the cone.The higher the corona voltage,the greater the collection efficiency of particle,especially the particles of relatively large-size,it is beneficial for relatively large-sized particles to be captured in this region.The faster the speed of particles movement,the greater the collection efficiency of the relatively large-size particles,and the smaller the collection efficiency of the relatively small-size particles.The shorter the insertion length of the exhaust pipe,the greater the collection efficiency of particles in the region.In the exhaust pipe.The higher the corona voltage,the higher the collection efficiency of the relatively small-size particles,which is conducive to the capture of small particles.The faster the speed of particles movement and the shorter of the exhaust pipe insertion length,the smaller the collection efficiency of the relatively small-size particles in this region.