Study On Impingement Characteristics Of Acidic Oil Biodiesel Under High Ambient Pressure And Common Rail Condition

The performance index,such as power, economy and emission performance of diesel engine, is closely related to the combustion processes in the combustion chamber, and the combustion processes is closely related to the spray mixing processes of fuel.This topic through the acidified oil study on biodiedel spray impingement characteristics, provides a theoretical basis and technical guidance for the corresponding applicationon diesel engine.The impingemental experiment use the schlieren appratus and the high speed camera to record the fuel spray process synchronously. The experiment mainly studied the effects of blending ratio, common rail pressure, background pressure,impingement distance, impingement angle to impingement characteristic of the mixed fuel. Meanwhile the flow simulation inside the injector was done, and the effects of environment temperature and the turbulence intensity to impingement characteristic of the mixed fuel was investigated.The experimental results show that:the diffusion diameter and entrainment height of mixed fuel increases with the increasing of the biodiesel content;with the increase of common rail pressure, the diffusion diameter and entrainment height of mixed fuel increased,and the rebound volume of mixed fuel increases relatively and the atomization effect enhanced too; with the increase of background pressure,the spray head diffusion degree of mixed fuel increased,but the spray diffusion diameter and entrainment height decreased; with the increase of impingement distance, the spray diffusion diameter and entrainment height decreased, and the air entrainment near the wall was weakened; with the impingement angle increases, the air entrainment near the wall was strengthened,the radius of upstream of impingement spray reduced,down-stream of the spray radius enlarged.The simulation results show that:When the environment temperature is lower, the penetration velocity of spray is small, and the evaporation rate of the drop is slower, the droplet size is larger; And with the environment temperature increases, the spray penetration velocity becomes large,and the evaporation rate of the drop expedited, the atomization effect of spray after impingement obviously enhanced;The development velocity of wall beam along the turbulence is larger than that of aganist the turbulence, and when the turbulence intensity increased to a certain extent, the wall beam just appeared in the clockwisedirection of the turbulence.The stronger air turbulence can increase the space propotional from impingemented fuel, accelerate the mixing of fuel and air in the space.