对置活塞二冲程柴油机换气子阶段完成比例研究

The influences of the free exhaust, discharge and additional scavenging phases of opposed-piston two-stroke (OP2S) diesel engine on the scavenging process are studied. To understand the completion of different scavenging phases in the whole scavenging process is very significant in investigating the OP2S's scavenging process and the influences of scavenging parameters on scavenging process. A 1-D simulation model is established for an OP2S diesel engine, and the accuracy of the proposed model is validated. The completed proportions of different scavenging phases in whole scavenging process are studied from the quality change of carbon dioxide in cylinder. The results illustrate that the completed proportions of free exhaust, discharge and additional scavenging phases are 64.42%, 35.57% and 0.01%, respectively, under the simulation conditions of 1200 r/min, 0.013 MPa pressure difference and 0.18 MPa back exhaust pressure. If the engine speed increases, the free exhaust period decreases and the discharge period increases. The influencing effect of scavenging difference is similar with that of engine speed. The influence of exhaust pressure on the completed proportions of different scavenging periods is not significant but the carbon dioxide mass in cylinder varies significantly when exhaust pressure changes.