Study On The Effect Of Ethanol / Biodiesel /Diesel Mixed Ratio On Spray Characteristics

Taking ethanol/biodiesel/diesel as research object,physical and chemical properties and atomization quality of EBD blended fuel were studied in this paper,and the atomization quality of fuel was numerically calculated from the angle of theoretical research.The influence of blending ratio on the physical and chemical properties of fuel was studied by means of experimental method and theoretical calculation.The results show that biodiesel is a good cosolvent for diesel alcohol.Adding 25%volume fraction biodiesel can make the blended fuel which has 20%volume fraction of anhydrous alcohol have good stability.Cold filter plugging point,density,kinematic viscosity,surface tension and flash point temperature of blended fuel increased with the increase of biodiesel content,while decreased with the increase of ethanol content.The calorific value and cetane number of blended fuel is less affected by the blending amount of biodiesel,but decreased rapidly with the increase of anhydrous ethanol content.In order to make EBD blended fuel meet the requirement of physical properties of vehicle 0~#diesel oil,the anhydrous ethanol content in EBD blended fuel should be less than 18%volume fraction,and the biodiesel content should be less than 55%volume fraction.Building atomization quality evaluation test bench.Based on the conventional injection system,the influence of fuel blending ratio on atomization quality and the atomization stability of each EBD fuel were studied.Based on the electronically controlled high pressure injection system,the effect of the injection pressure and fuel injection pulse width on atomization quality were studied.The results show that the injection length is directly affected by the injection pressure and the injection pulse width,and becomes significantly larger with the increase of the two,but it is almost unaffected by the blending ratio.EBD fuel has good atomization stability performance,and the atomization quality of each fuel is basically unchanged after long-term closed placement.The atomization quality is affected by the mixing ratio,injection pressure and jet pulse width.The influence of injection pressure is particularly prominent,but it is less affected by the spray pulse width.Increasing the ethanol content,reducing the biodiesel content,or improving the injection pressure can make the proportion of droplets with small particle size become larger,the cumulative volume distribution curve shifts to the upper left corner,the average diameter and characteristic diameter become smaller,the spray cone angle becomes larger,and the atomization quality is improved.When the injection pressure is large,continue to increase the injection pressure or change the fuel blending ratio,which has little effect on the microscopic spray characteristics of the fuel,but the difference in macroscopic spray characteristics is still relatively obvious.Building atomization quality calculation model in Visual Fortran 6 platform,using Fortran to compile and compute program,the atomization quality of fuel was calculated theoretically and compared with the experimental results.The results show that the fitting and the experimental results have the same rule of PDF_N distribution.At the same time,the results of the two are similar in the small size,but the difference in the larger particle size is relatively large,but the difference between the two is not significant as a whole.The numerical simulation of atomization quality can be completed by using each calculation sub-model in this paper.