Experimental study on spray impingement during diesel engine starting

Abstract

A lot of research has been carried out in the field of improving combustion efficiency and reducing exhaust gas, but the phenomenon of engine fuel spray hitting the wall cannot be solved well all the time, thus the phenomenon will increase exhaust gas emissions and reduce combustion efficiency. Based on oil pump test bench of Diesel engine, we designed spray-wall impingement?s test, did high speed camera shooting to capture the relevant motion characteristics of fuel spraing-hitting the wall by mosquito-rope method, under the starting process, the influence of different working condition on spray impingement was studied. The results showed that under the condition of high injection rate/low gas pressure, the impact time gets early and the diffusion range gets to be increased. When the injection rate/background gas pressure is constant, the diffusion distance will change dynamically due to the wall roughness, that is to, increase first and then decrease. The increase of the roughness of the contact wall will promote the increase of the height of spray impingement, however, as the temperature of the contact wall rises, the difference in height of spray impingement gets to be decreased due to roughness. When the wall roughness is small, increasing the wall temperature will reduce the horizontal development distance of spray, increases roughness, the difference in height of horizontal development distance gets to be decreased due to wall temperature.