四气门火花点火式发动机缸内的空气运动

在倒拖工况下对四气门火花点火式发动机缸内空气运动进行了实验研究和分析，采用加长活塞结构及透明活塞顶，利用激光多普勒测速仪（ＬＤＡ），分别对气缸轴线上、燃烧室内和气缸上部两个平面上的速度进行了测量，结果表明：在进气过程中，抿内产生了双涡结构；在压缩过程初期，由于从进气门流向排气门侧的滚动涡旋逐渐增强，而另一侧的反向涡旋逐渐减弱，形成了单一大尺度的滚动涡流；在压缩过程中后期，滚流经历了加强、衰减、变形

EXPERIMENTAL STUDY ON IN-CYLINDER AIR FLOW IN A FOUR-VALVE SPARK IGNITION ENGINE

An experimental work conducted on the incylider flow fields in a four valve S.I.engine under motored conditions is described in this paper.A four valve S.I.engine was converted into an experimental engine,having an elongated piston and transparent piston head.The results of the LDA measurements of the air motion at points on the cylinder axis,and on two horizontal lines in the combustion chamber and in the upper part of the cylinder show that a twin vortex is formed in the cylinder during the intake process,and a single large scale tumble vortex is finally evolved at the initial stage of the compression process after the inlet valves to be closed.At the middle and later stages of the compression process,the tumble motion experiences a process of enhancement,decay,distortion and smash.