GDI汽油机混合气形成和碳烟生成过程的三维数值模拟

发布时间：2018-02-27 00:01

本文关键词： 颗粒物缸内直喷汽油机(GDI) 碳烟模型池火混合气形成数值模拟　出处：《中国电机工程学报》2016年16期 　论文类型：期刊论文

【摘要】：缸内直喷汽油机(gasoline direct injection,GDI)的颗粒物排放问题越来越引起人们的重视。为解析GDI汽油机缸内碳烟生成机理,文中提出了一种改进的两步法碳烟模型,将该模型应用于Kiva-Chemkin软件中,对一款典型GDI汽油机的喷雾碰壁、混合气形成、燃烧和碳烟生成过程进行了三维计算流体力学(CFD)数值模拟。结果表明,GDI汽油机的碳烟主要源于缸内油气混合不均、壁面油膜的燃烧即池火燃烧。在均质混合气工作模式下,增加喷油提前角可使燃油雾化更好、油气混合均匀,从而降低碳烟生成。但如果喷油提前角过大,会导致喷雾碰壁,引起碳烟生成量急剧增加。在分层混合气工作模式下,碳烟主要来源于局部浓区。过早喷油不利于产生喷雾诱导的滚流,不利于油气均匀混合,会产生局部燃油浓区,从而导致缸内碳烟生成量较高。结果表明,文中提出的碳烟模型可较好地预测缸内碳烟生产过程。
[Abstract]:GDI engine (gasoline direct, injection, GDI) particulate emission problems have attracted more and more attention. For the analysis of GDI gasoline engine in cylinder soot formation mechanism, this paper proposes an improved two step soot model, the model is applied to the Kiva-Chemkin software, on a typical GDI gasoline engine spray impingement, mixture formation, combustion and soot formation process of three-dimensional computational fluid dynamics (CFD) numerical simulation. The results show that the soot GDI gasoline engine is mainly due to the cylinder oil and gas mixed uneven wall oil film combustion of pool fire. In the homogeneous mixture the work mode, increase the fuel injection advance angle can make better fuel atomization, oil and gas are mixed evenly, thereby reducing soot formation. But if the injection advance angle is too large, will cause the spray impingement, caused by soot emissions increased dramatically. In the stratified mixture mode, main soot To come from local concentrated area. Early injection is not conducive to producing the spray induced rolling flow, is not conducive to oil and gas mixing, can cause the local fuel concentration zone, resulting in cylinder soot formation was high. The results show that the soot model proposed in this paper can better predict the soot production process in the cylinder.

【作者单位】：清华大学汽车安全与节能国家重点实验室;
【基金】：国家重点基础研究发展计划项目(973项目)(2013CB228502)~~
【分类号】：U464.171

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