Investigation On Characteristics And Modes In Electrostatic Atomization Of Liquid At Capillary Outlet

Before the fuel enters the combustion chamber,it must be broken into tiny droplets through the atomizing device,thereby the specific area of droplets are increased,and they mix with the air fully so that the fuel can be burned stably and adequately.Electrostatic atomization is the process of overcoming surface tension to break down the droplets by using the electrostatic force.The process can be controlled by regulating voltage,and the droplet dispersion is strong and the particle size is finer.Therefore,compared with other atomization methods,electrostatic atomization can significantly enhance atomization quality and improve combustion efficiency.Therefore,investigation on characteristics and modes in electrostatic atomization of jet fuel is of great significance for alleviating the energy crisis and reducing the emission of incomplete combustion pollutants.Although many domestic and foreign scholars have conducted a lot of research on electrostatic atomization of fuel for a long time,most of the research is aimed at gasoline and diesel for common engines.There is few research on jet fuel,which is a special kind of fuel for aero engine.Therefore,in this paper we focus on the investigation on characteristics and modes in electrostatic atomization of jet fuel at capillary port.The main contents of this paper include the following points:(1)The charging mode,charged atomization mechanism,and force condition of electrostatic atomized droplets are analyzed theoretically.There are two ways of liquid charging: natural charging and forced charging.In practice,the charged droplet breaks up at about 70% of the Rayleigh limit.In the electric field,charged droplets are mainly affected by electric field force,mass force,coulomb force,gradient force and viscous resistance.(2)An electrostatic atomization experiment system is designed and built.Detailed planning is carried out for the experiment.The main experimental devices are selected,and jet fuel,deionized water,and anhydrous ethanol are selected as the experimental mediums.(3)The electrostatic atomization modes of jet fuel are classified and compared with those of deionized water and anhydrous ethanol.As the voltage continues to rise,the electrostatic atomization modes of jet fuel experiences the drop pattern,oscillating pattern,unstable jet pattern,stable jet pattern,and unstable ionization pattern.(4)As voltage increases,the droplet diameter and liquid bridge length of jet fuel,deionized water and absolute alcohol at capillary port are extracted and analyzed.When the flow rate is 1 ml/min,the liquid bridge lengths of three mediums increase with voltage at the capillary port,and the droplet diameters decrease with voltage.(5)A series of experiments on electrostatic atomization of jet fuel at different flow rates was conducted,and characteristics in electrostatic atomization of jet fuel are summarized as follows: The flow rate ranges from 0.18 ml/min to 2.55 ml/min when stable jet pattern of jet fuel appears,and voltage ranges from 20 kV to 25 kV.The larger the flow rate is,the higher the falling frequency of jet fuel at the same voltage,and the larger the increase range of falling frequency of jet fuel with voltage is.The bridge length of each flow rate of jet fuel increases with voltage.When the flow rate is 0.1 ml/min,the trend of droplet size decreases with voltage firstly,then increases.With the increase of flow rate,the increasing trend gradually decrease,and there is no increasing trend when the flow rate is 1 ml/min.