非定常気体噴流への周囲空気導入に関する研究 : 空気導入の空間的・時間的変化

抄録

It is very important to investigate the entrainment process of ambient air into a transient gas jet in order to discuss the combustion of the fuel jet in gas diesel engines. In this study, a gas jet was injected into still air during a very short period of 11.5 milliseconds. Cross sectional images of the jet were visualized at various times from the initiation of the injection. The mass of air entrainment into the jet was also obtained from the path line method proposed by the authors, and the spatial and temporal change of the ambient air entrainment into the jet was approximately clarified. The air from upstream side of the unsteady part of the jet is entrained more than that from the steady part. The ensemble averaged air mass entrained from across section perpendicular to the jet axis is axisymmetric; however, the entrainment mass of every jet is not always axisymmetric.