Numerical Study On Corona Induced Ionic Wind Characteristics In Sharp Configurations And Its Application In Heat Transfer Enhancement

Since the 19 th century,gas discharge has been widely used in industry,medical treatment and people’s life.Electrostatic precipitation(ESP),heat and mass transfer enhancement,flow control,and electrospray are the common applications.Corona Discharge is an important form of gas discharge.Heat transfer enhancement by using the ionic wind generated by corona discharge has attracted more and more attentions from researchers in recent years due to its advantages of no vibration,low noise,fast response and compact structures.In this paper,corona discharge and induced ionic wind in various sharp electrode structures are studied by numerical simulation.And we also evaluate the capability of heat dissipation enhancement of “ionic wind generator” in “needle-ring” configuration.Based on Fluent software,the numerical simulation module of single species model for corona discharge is established.Coupled with the flow field module and energy module within Fluent,the multiphysical field simulation platform of HVDC corona discharge is realized.One of the key problem of corona discharge simulation is the extremely steep gradient of electric field intensity near the corona electrode.A very precise grid is needed at this location.Therefore,a twodimensional orthogonal grid generation method based on the orthogonality of electric line and equipotential line is developed in this paper.Multiple examples are used to fully verify the grid quality and the EHD simulation platform.The verification results show that the orthogonal grid generated by the new method is of good quality and can effectively reduce the computational grid number.The EHD numerical simulation platform can apply to calculate the single species model corona discharge problem and obtain satisfactory results.The ionic wind problems of three geometric models,blade-plate,needle-plate and needlering,are numerically studied.The influences of the main parameters such as voltage and electrode spacing on corona current,ion wind velocity and flow morphology are analyzed.The results show that the current approximately varies with the voltage as a quadratic function,while the trend of velocity varies differently with the voltage due to the differences of corona structures.By comparing the two charge injection mechanisms,it is found that the simulation results based on Kaptzov hypothesis show a relatively larger velocity value,while the simulation results of linear injection law are in good agreement with the experimental values.Moreover,as the voltage increases,linear injection parameters should be reduced appropriately.Finally,In order to explore the application of ion wind in strengthening the heat dissipation of electronic chips."ionic wind generator" in needle-ring configuration used to enhance heat dissipation of fixed-heat flux copper sheet are simulated.simulation results show that the ion wind can effectively improve the heat transfer coefficient on the surface of the copper,lower the temperature of the copper.For the heating condition with the heat flux below 2000 W/m2,Ionic wind has good cooling capacity.