Research On Adhesion And Velocity Characteristics Of Diesel Spray Impinging On Wall

The full atomization of diesel spray contributes to the full combustion whic h can reduce energy consumption and soot emission.In recent years,researchers have turned to the research of diesel spray impingement,and many works were presented to investigate the concentration distribution characteristics and velocity characteristics of the spray impingement,while the effect of influence factors,s uch as in-cylinder gas pressure,injection pressure,impingement distance and imp ingement angle,on the spray impingement was discussed.However,these current researches on the spray impingement concentrate on the concentration distributio n characteristics and velocity characteristics,and paying little attention on the det ails of the fuel adhesion characteristics of the spray.In fact,the adhered fuel pa rticles on the walls may lead to the incomplete combustion and then increase th e fuel consumption and emissions.Moreover,the spray velocity on the wall can reflect the momentum of the spray.After the spray impingement,the longer fue l diffusion distance around the spray circumference or the higher diffusion distanc e along the nozzle axis direction generally means the better atomization of the s pray.Therefore,this paper presented a research on the adhesion characteristics an d velocity characteristics.In this study,the adhered fuel quality on the walls of a spray was measured by using a constant volume bomb system to illustrate the adhesion characteristics of the spray impingement.The spray process was visualized by some continuous images captured by a high speed camera and its PIV software,and these images were imported into the Matlab software to analyze and determine the spray velocity data.Meanwhile,the effect of influence factors,such as disk diameter,ambient pressure in cylinder,injection pressure,impingement distance,impingement angle and nozzle diameter,on the fuel adhesion and velocity characteristics of the spray impingement was experimented.The test results show that the quality of adhesion fuel is influenced by the impingement distance.The fuel adhesion rate is directly related to the diameter of spray circumference,and it varies in negative correlation with the injection pressure.When the impingement angle is 20 degrees,the spray velocity is bigger than the vertical collision.With the increasing of the ambient pressure or spray pressure,the velocity of the upper area(H>2mm)of the impinging spray is higher,and the radial spray diffusion distance is larger.The smaller nozzle hole leads to the greater steady maximum velocity and the radial distance of the spray diffusion.The characteristics of spray impingement under the condition of single-hole and non-evaporation in this paper are the basis of researching the various characteristics of diesel spray impingement in real engine,and can provide data reference and theoretical basis for future research,and canprovide a strong basis for enterprise design and manufacture.The findings of this study on the spray impingement characteristic with the conditions of single-hole and non-evaporation respectively can give a basic understanding for the actual spray impingement of diesel engines,and it also provide a guidance for the future research and the organization of injection strategy.