Analysis Of Electrohydrodynamic Flow On Flow Pattern Discharges In Spiked-electrode Electrostatic Precipitator

Because of ionic wind had huge influence on collection efficiency inside ESP,the removement of submicron particles has always been a problem.In order to improve the dust removement efficiency,the comprehensive analysis about the flow field which was influenced by ionic wind inner ESP is required.Then put forward the optimization plan for the flow field.By using 3D-PIV(Particle Image Velocimetry),Combining with RS spiked electrodes and C480 electrode plates,which were always utilized in industry,this article analyzed the ionic wind specific influence near the electrode plate in order to figure out how ionic wind did on efficiency in ESP.In addition,three dimensional characteristics of ionic wind under HighVoltage discharge has been shown off by observing the flow maps.Next,by using different plate distance between 400mm-600 mm,this thesis revealed effect of ionic wind in flow field.Finally,Found a suitable wire-plate configuration and distance through adding another spike electrode.As the visualization results suggest:(1)It was found that a high speed jet flow will generate from tips of spike electrode.Jet flow formed as vortices which entrained particles from plate to main flow.As the voltage increasing in ESP,the vortices induced by ionic wind will continuously get close to spike electrode and became larger.Different tips direction had different ionic wind affect.The particles ran out of ESP because of the jet flow acceleration when tips had same direction with main flow.After tips were opposite to main flow,the downstream vortices drived particles to plate which promoted the collection of particles.(2)From the streamlines,most of particles moved to plate and caught by plate with 0.2m/s main flow speed.But the ionic wind had a strong effect improved the flow speed which enhanced the Re-entrainment possibility of particles around the electrode plate.When main flow speed reached 0.6m/s,due to weakness of ionic wind,the flow speed around electrode plate was slower and the Re-entrainment around the plate was undermined,while more particles ran away from ESP.The speed near the plate respectively reduced 15% and 40% with the tips had same direction and opposite direction to main flow in case of 75 k V.(3)Three dimensional streamlines showed that vortices had obvious three dimensional feature.As a consequence,The flow velocity field was regular when tips had the same direction with main flow.In contrary,the flow velocity field was unregular when tips had opposite direction,especially in vortices district.In addition,the bend corner of C480 electrode plate could reduce the flow speed around it to prevent re-entrainment happened to submicron particles.(4)Parametric analysis inducted that increased the distance between electrode plate resulted in lower discharge current which lead to the weakness of ionic wind.During main flow reached 0.4m/s,most of particles drifted out of ESP directly.(5)After adding another spike electrode,the flow velocity field had the similar characteristic under different shooting height.Generally,the interaction of ionic wind between spike electrodes is strong under 200 mm distance,whereas none phenomenon with 300 mm distance.Further more,it would have a higher collection efficiency due to plenty of particles remained in ESP and turned toward to electrode plate with opposite tips.