Basic Research On The Generation Of Gas-liquid Two-phase Flow And Its Effect On Atmospheric Plasma

In recent years,the physical and chemical properties of plasma have become more and more important in the fields of biomedicine,environmental protection,and material processing.However,for precision application scenarios such as biomedicine,there are still bottlenecks such as low types of effective chemical components and difficult control.For largescale applications such as environmental protection,there are bottlenecks such as high-power consumption and low energy efficiency.In the above applications,the plasma is required to be generated under atmospheric air in most cases.The composition of the chemical substances in the plasma is mainly composed of atoms and molecules derived from nitrogen and oxygen,and contains trace amounts of substances derived from water molecules.In those plasma applications that are mainly based on chemical effects,it is not enough to rely solely on the physical characteristics of increasing the density of free electrons and expanding the range of plasma generation.In this context,this paper proposes to use the gas discharge Joule heat as the heat source to achieve the boiling phase change of the liquid working fluid,and to pass the generated gas-liquid two-phase into the atmospheric plasma,thereby changing the material composition in the plasma.Joule heat is a concomitant phenomenon in most discharge processes.It can technically come from the discharge system itself without additional energy consumption,which is very suitable for application scenarios with high energy efficiency requirements such as plasma environmental protection.For scenes such as plasma medicine,Joule heat is controllable and harmless,and also has good compatibility.Thus,this method of introducing new material components into the plasma can improve energy efficiency and reduce system complexity to a certain extent.In addition,the physical processes,phase transitions,and heat transfer mechanisms of the plasma heat source gas-liquid two-phase flow,as well as scientific issues such as their effect on atmospheric pressure plasma,are also new multidisciplinary topics worth exploring.In order to simplify the decoupling and study the basic phenomena and mechanisms,this paper heated an aqueous sodium chloride solution through an independent heat source to observe and analyze the physical process of gas-liquid two-phase flow and its impact on another plasma region.The main research work is as follows:Firstly,the experimental system design and construction of the effects of gas-liquid two-phase flow on the atmospheric plasma state.For the difficult problem of accurate analysis and diagnosis of boiling evolution and plasma state,this paper uses the schlieren analysis system to perform the charac-teristic diagnosis of the experimental process.Based on the principle of optical interference diagnosis and combining with the needs of specific experiments,a full-featured schlieren analysis system has been set up,and appropriate changes and improvements have been made based on the original two-beam interference diagnosis optical path.A beam expander was added for a larger diagnostic area,making it more suitable for diagnostic studies of experimental procedures.Secondly,the high-speed streaking and imaging experiments of the gas-liquid two-phase boiling flow using the gas discharge Joule heat as the heat source.This paper has found the evolution of the boiling process and confirmed the generation of the gas-liquid two-phase flow.In this paper,a boiling experiment was performed using Joule heat generated by gas discharge plasma as a heat source to heat the sodium chloride aqueous solution in the tube.At the same time,a high-speed camera was used to dynamically observe the evolution of different parts of the boiling tube,and a built-in schlieren analysis system was used to diagnose the characteristics of the nozzle area.The evolution of the boiling process using plasma as the heat source was discovered through experiments,that is,the process of the liquid in the tube from the generation of bubbles to the rise of the liquid level to the two-phase flow under the action of gas discharge Joule heat.Thirdly,experimental research on the effect of boiling gas-liquid twophase flow on atmospheric pressure plasma.Aiming at the types and control of chemical components in the plasma under atmospheric air conditions,this paper passed the gas-liquid two-phase generated by boiling into the plasma area,and used high-speed cameras,schlieren analysis systems,and spectral diagnostic systems to conduct experimental experiments.The dynamic observation,characteristic analysis and parameter diagnosis were carried out,and the changes of plasma distribution area,density parameters and chemical composition after the introduction of two-phase flow were obtained.The experiment compared the state changes before and after the gas-liquid two-phase flow into the plasma region,and obtained the influence of the gas-liquid two-phase flow on the physicochemical properties of atmospheric pressure plasma.