Location of the First Auto-Ignition Sites for Two HCCI Systems in a Direct Injection Engine
Location of the First Auto-Ignition Sites for Two HCCI Systems in a Direct Injection Engine
复制标题
直喷发动机中两个 HCCI 系统的第一个自燃点的位置
DOI：
10.4271/2004-01-0564
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
I. Denbratt
中科院分区：
文献类型：
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作者：
Lucien Koopmans;J. Wallesten;R. Ogink;I. Denbratt
为了阐明控制均质装药压缩点火（HCCI）发动机自燃时间和总燃烧时间的过程，研究了自燃点在空间和时间上的分布。在全可变气门驱动的光学发动机中，利用激光诱导荧光（LIF）测量甲醛，研究了HCCI燃烧的光学诊断。该发动机在两种不同的HCCI模式下运行。在第一种方法中，通过加热进气来达到自燃温度，而在第二种方法中，使用负阀重叠来捕获先前燃烧循环中的残余质量。两种方法都将燃料直接引入燃烧室。为了补充这些实验，对两种生成hcci的方法进行了气体交换和压缩冲程事件的三维数值模拟。应用STAR CD程序预测压缩行程结束时缸内局部混合温度、残余气体分数（RGF）和等效比的分布。了解这些分布是很重要的，因为它们强烈地影响着HCCI燃烧的点火时间和燃烧持续时间。从计算的分布图中选择的点被用作0-D详细化学计算的初始条件，使用SENKIN代码识别导致首次自燃的属性组合。将相应的点追溯到STAR - CD网格，可以获得有关自动点火地点位置的信息。用这种方法得到的结果与光学测量得到的自燃位置吻合得很好。
To elucidate the processes controlling the auto-ignition timing and overall combustion duration in homogeneous charge compression ignition (HCCI) engines, the distribution of the auto-ignition sites, in both space and time, was studied. The auto-ignition locations were investigated using optical diagnosis of HCCI combustion, based on laser induced fluorescence (LIF) measurements of formaldehyde in an optical engine with fully variable valve actuation. This engine was operated in two different modes of HCCI. In the first, auto-ignition temperatures were reached by heating the inlet air, while in the second, residual mass from the previous combustion cycle was trapped using a negative valve overlap. The fuel was introduced directly into the combustion chamber in both approaches. To complement these experiments, 3-D numerical modeling of the gas exchange and compression stroke events was done for both HCCI-generating approaches. The STAR CD code was applied to predict the distributions of the local mixture temperature, residual gas fraction (RGF) and equivalence ratio throughout the cylinder at the end of the compression stroke. Knowledge of these distributions is important as they are strongly affect the ignition timing and burn duration of the HCCI combustion. Selected points from the calculated distribution maps were used as initial conditions for 0-D detailed-chemistry calculations, using the SENKIN code to identify combinations of properties that lead to first auto-ignition. Tracing corresponding points back to the STAR CD mesh gave information about the location of the auto-ignition sites. Results obtained in this way corresponded well to the auto-ignition locations derived from optical measurements.