提高四气门汽油机缸内滚流强度的研究

在四气门汽油机中，运用滚流运动组织快速燃烧过程或混合气分层稀燃过程，都需要提高滚流强度。作者在一台单缸四气门汽油机上，通过 Ｌ Ｄ Ａ 测量，研究了滚流的形成过程，提出了提高滚流强度的机理，并对进气道结构、燃烧室内进气门出口侧壁屏蔽对滚流运动强度的影响进行了初步研究。研究结果表明，在滚流形成过程中，缸内首先出现双涡旋结构，以后演变成为单涡旋结构的滚流运动。增加流经排气门侧的进气气流或抑制直接沿进气门侧缸壁流入气缸的气流，都能提高滚流强度。

A Study of Increasing In-Cylinder Tumble Intensity of Four-Valve S.I.Engines

In four valve spark ignition engines,tumble motion in the cylinder is required to be intensified in order to improve combustion process in general homogeneous mixture combustion system or to stratify the air fuel mixture in lean burn combustion system.In this paper,the formation of tumble motion in the cylinder of a single cylinder four valve gasoline engine was studied by using LDA measurement,and the cause to increase tumble intensity was analyzed.In addition,the effects of configuration of inlet ports and the shields of side chamber wall around the two inlet valves on tumble intensity was tested.The results show that in the formation process of tumble during the intake stroke,two vortexes are generated in the cylinder.During the early period of compression stroke with piston upward moving and inlet valve closing,a single vortex,i.e.tumble,is evovled into.Tumble intensity can be increased by means of enhancing inlet flow into the cylinder along the roof chamber wall on the side of exhaust valves or of blocking inlet flow directly into the cylinder along the cylinder wall.