Simulation,Design And Experiment Research Of Atmospheric Pressure Air Plasma Jet Device

In this paper,the atmospheric pressure air plasma jet?Air APPJ?device and its fluid and discharge characteristics are studied by simulation and experiment.Firstly,the optimal electrode parameters of APPJ gun are obtained by electric field simulation,and then two APPJ devices are designed and prepared.The atmospheric pressure air plasma jet is successfully generated by the high-voltage AC power supply excitation,and the discharge characteristics are experimentally studied.The main research contents are summarized as follows:?1?Simulation part,including electrostatic field simulation and airflow field simulation.The first is the electrostatic field simulation.The two-dimensional axisymmetric model of the needle-metal nozzle structure and the needle-ring structure is established in the COMSOL Multiphysics simulation software.It is found that the potential and electric field distributions of the two are similar,but the maximum electric field strength generated by the former is significantly greater than the latter.In addition,a simulation model of the pre-ionization double high-voltage electrode structure is established and its electric field distribution is simulated.Then,based on the needle-metal nozzle structure,the influence of the parameters such as the radius of curvature of the tip,the distance between the electrodes and the diameter of the needle electrode on the spatial distribution of the electric potential and the electric field is studied.It is found that the radius of curvature of the tip has a great influence on the maximum field strength.Then there is the airflow field simulation,mainly for Ar as the working gas.According to the size of Reynolds number,it is divided into two modules:laminar flow and turbulent flow.The flow velocity distribution and Ar molar distribution under two flow states are analyzed and compared.It is found that the velocity distribution and the molar distribution of laminar flow are similar.The ratio of the axial mole fraction to the total mole fraction increases with the increase of the flow velocity;the velocity distribution and the molar distribution of the turbulent flow are significantly different,and the velocity distribution in the front section of the jet is divergent.The molar distribution is more concentrated,and the streamline diagram shows that this is the result of air entrainment into the Ar gas stream.Then follows the simulation of the effect of different nozzle diameters on APPJ characteristics.?2?The experimental part is a jet-discharge experiment of a needle-metal nozzle structure and a pre-ionization DBD structure,respectively.Firstly,a high-frequency high-voltage AC power source is used to excite the plasma gun of needle-metal nozzle structure to generate an atmospheric pressure low-temperature plasma jet,and the working gas including air,N₂ and Ar,where the N₂ and Ar jets are used for comparison with an air jet,including comparison of characteristics such as jet length,gas temperature,and discharge voltage.It is found that the parameters of the nitrogen and air jets are relatively close,and the discharge voltage and power of the Ar jet are much lower than the air jet,and its size is also small.After that,the regulator output voltage and air volume flow are changed respectively to study the effects of these two variables on the characteristics of jet gas temperature and discharge power.Thereafter,the pre-ionized dual high voltage electrode structure APPJ device is used for air,nitrogen,and argon discharge.The results show that the device is capable of ionizing the air to generate plasma,but the discharge intensity is low,and the volume of plasma generated is also small,which is basically confined to the dielectric tube.When N₂ and Ar are ued as working gas,it can produce APPJ with a gas temperature of room temperature and a long length.Compared with the needle-metal nozzle structure,the needle-metal nozzle structure is more suitable for nitrogen and air discharge,while DBD is suitable for the discharge of inert gas with a lower breakdown voltage,which corresponds to the results of the electric field simulation in the previous section.The research content of this paper provides theoretical and technical support for the design and parameter optimization of atmospheric air plasma jet device,which has certain significance for promoting the development of plasma jet.