换气与压缩过程对汽油机燃烧特性的影响研究

摘要

For a gasoline engine with turbocharging and intake port injection ,the effect of exchange and compression process on combustion characteristic was researched and the power ,fuel economy and combustion characteristic were mainly analyzed based on the engine test bench data .It was found that the change of valve timing had great influence on combustion .The change would lead to a large increase of combustion efficiency and decrease of knock trend .With AVL-fire software ,the CFD simulation of intake and compression process was conducted .The results show that the combustion characteristic in exchange and compression process not only depends on instantaneous tumble flow ratio and in-cylinder average turbulent kinetic energy , but also turbulent kinetic energy near spark plug .That is to say ,the main influencing factor of combustion characteristic is tur-bulent kinetic energy near spark plug at the top dead center of compression .%针对增压气道喷射汽油机进行了发动机换气与压缩过程对燃烧特性的影响研究 ,对比了两种状态下的气门升程与配气正时 ,基于发动机试验台架测试数据 ,重点分析了发动机动力性、经济性和燃烧特性.试验数据表明了配气相位的改变对燃烧有较大的影响 ,可使燃烧效率大幅度提高 ,爆震倾向减小.同时基于AVL -fire软件进行发动机进气与压缩过程三维CFD分析 ,分析结果表明 :对燃烧特性的影响不能仅靠瞬态滚流比和缸内平均湍动能进行判断 ,真正影响燃烧的是火花塞附近湍动能的变化 ,即发动机换气与压缩过程对燃烧特性的影响来自压缩上止点火花塞附近的湍动能.