汽油机气缸中滚动气流运动对发动机性能的影响

Effect of In-cylinder Tumbling Air Flow on Engine Performance in S.I.Engines

本文通过调整导气屏气阀位置产生大范围变化的缸内气流运动形式。用传统的稳流试验台和作者最近研制的测缸内滚流运动的稳流试验台对各种气流运动形式进行稳流试验，用二维激光多普勒测速仪在反拖的发动机气缸内测量缸内紊流运动的发展变化并用着大发动机的性能实验结果来分析各种气流形式的涡流、滚流和紊流特性。试验结果表明，在气缸中产生较强的横轴涡流即滚动或接近滚动气流运动时，燃烧室内的紊流强度可获得较大的提高，性能也有明显的改善，而传统的立轴涡流对汽油机燃烧室内紊流强度没有明显增加，对发动机的燃烧和性能也不带来改善。

Quite different in-cylinder bulk flow modes are achieved by tuning a shroud inlet valve of a single cylinder CAI 102 S.I.engine.Two sets of steady flow tests for the different in-cylinder bulk flow modes are carried out on both conventional swirl steady flow test rig and tumble steady flow test rig, or named as tumble meter,which was developed by the authors recently,the turbulence intensity and its variation in the cylinder and combustion chamber are measured by a 2D Ar-ion LDA System in a motored single cylinder engine and the engine Performance is measured in a fire engine for correlating the combustion with the bulk flow modes of swirl and tumble and their characteristics of turbulence.The experimental results show that when the bulk flow is in tumble modes or closes to tumble mode,higher turbulence intensity in combustion chamber at TDC can be obtained and the engine performance can be improved obvionsly,when the in-cylinder bulk flow is in traditional swirl moode howecer,the turbulenc intensity at TDC would not increase and consequently the engine performanc won't be improved either.