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本文利用气体模拟技术研究了直喷式柴油机的燃油喷雾特性。研究结果表明,瞬态燃油喷雾的前端存在一个强烈的紊流混合前锋区,其后是浓度分布处于平衡状态的雾锥。雾锥轴线上的浓度随贯穿距离的增加而线性衰减;雾锥的径向浓度分布与剖面至喷孔的距离有关,对于充分发展的雾锥,径向浓度不同于稳定自由射流的浓度分布,而服从指数型分布规律。当喷雾与壁面撞击时,可观察到紊流混合过程出现一个从强化到减弱的有利于混合的过渡过程,但过量壁喷会在壁面上出现浓混合气层的堆积,恶化混合。
In this paper, using gas simulation technology to study the direct injection diesel engine fuel spray characteristics. The results show that there is a strong turbulent mixing front in the front of the transient fuel spray, followed by the cone of the cone at a balanced concentration distribution. The concentration on the cone axis decreases linearly with the increase of the penetration distance. The radial concentration distribution of the cone is related to the distance from the section to the injection hole. For the fully developed cone, the radial concentration is different from that of the steady free jet, And obey the exponential distribution law. When the spray impinges on the wall, a turbulent mixing process is observed that results in a turbulent-to-abusive, transitional process that favors mixing, but excessive wall blow-up causes a build-up of dense gas layers on the wall, deteriorating the mixing.