Study On The Electrospray And Combustion Characteristics Of Ethanol In The Counter-flow Combustor

In recent years,with the development of nanometer and micromachining technology,many equipments have the characteristics of miniaturization and multifunctional,and it is important to search for a method for efficient combustion.Liquid hydrocarbon fuel has wide application prospect due to its high energy density and less pollution advantages,and the combustion of atomized liquid fuel is an effective way to supply energy continuously in small equipments.However,the combustion of atomized liquid fuel is still in development,it is significant to study its internal mechanism moreover.In order to investigate the electrospray and combustion characteristics of liquid fuel,this paper creatively designs a new counter-flow combustor to study the combustion of atomized liquid fuel,which combines electrospray technology and counter-flow combustion technology.Experiment explores the conditions of steady combustion of electrospray in the counter-flow combustor were carried out using ethanol as fuel.Also,focusing on the cone-jet mode of electrospray,the spray morphology,the range of operating voltage,droplets size and velocity distribution of spray were obtained by experiments.The effects of different electrode structures,fuel flow rates and electrode voltages were analyzed.Finally,the combustion characteristics of ethanol electrospray with single electrode structure in the counter-flow combustor was studied,which including the shape,temperature and stability limit of flame.The mechanism of the combustion based on atomized liquid fuel was also analyzed.The results show that with the increase of ethanol flow rate,the range of operating voltage basically unchanged,the boundary between atomized core regions and satellite regions of the spray gradually becomes blurred and more liquid columns are formed in two kinds of electrode structures which based on the cone-jet mode of eletrospray.On the position of z=14 mm,droplets size of the spray in two kinds of electrode structure decreases firstly,and then basically unchanged,and droplets velocity of the spray also decreases when increasing the radial distance.With the increase of ethanol flow rate,droplets size of the spray increases,but droplets velocity of the spray is less affected by the variety of ethanol flow rate when the voltages keep constant.Compared with the electrospray in the singe electrode structure,electrospray in the double electrode structure has multiple operating voltage ranges of cone-jet mode,more uniform droplets velocity distribution of spray and droplets size of spray is 37.5 percent of that in the single electrode structure.The shape of spray tends to gather when increasing voltages of the ring electrode.It is significant to install ring electrodes,which may improve the overall control ability of the voltage to spray,and has high engineering application value.With the increase of ethanol flow rate,the stability limit of flame increases in a single electrode counter-flow combustor.The flame remains stable at the equivalent ratio is less than 1 but oscillates when the equivalent ratio is more than 1,dimensionless diameter of the flame decreases with increasing equivalent ratio.The stability of flame can improve with the increase of ethanol flow rate.Dimensionless diameter of the flame and flame temperatures both decrease due to the increase of the strain rate.The stability of the flame is little effected by the equivalence ratio at different ethanol flow rates,but flame temperatures are great effected by the change of strain rate.