Characterization of an in-cylinder flow structure in a high-tumble spark ignition engine
Characterization of an in-cylinder flow structure in a high-tumble spark ignition engine
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DOI：
10.1243/1468087042320924
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发表时间：
2004-10
影响因子：
2.5
通讯作者：
Yixuan Li;Hua Zhao;B. Leach;T. Ma;N. Ladommatos
中科院分区：
文献类型：
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作者：
Yixuan Li;Hua Zhao;B. Leach;T. Ma;N. Ladommatos
利用数字粒子图像测速仪(PIV)对三气门双火花点火(SI)发动机进气门下缘部分被遮盖而产生的缸内强滚流进行了测量。详细分析了体流特征、周期变化、流速脉动频谱、大尺度和小尺度脉动动能以及积分长度尺度。文中还讨论了这些流动特性对电荷分层以及随后的着火和燃烧过程的可能影响。结果表明，直到压缩冲程的后期，滚流旋转轴方向的速度分量都很小，为强滚动场的特征。体流的循环变化虽然仍然存在，但已显著减少。在压缩过程接近尾声时，发现翻滚崩塌后，低频和高频速度波动都很大。沿圆柱轴方向的速度脉动分量具有较高的频率特征。在压缩过程中发现了4-9 mm的完整长度尺度。
Abstract A strong in-cylinder tumbling flow, which was produced by partially shrouding the lower periphery of the inlet valves, was measured in a three-valve twin-spark spark ignition (SI) engine using digital particle image velocimetry (PIV). Characteristics of the bulk flow, cyclic variation, frequency spectrum of velocity fluctuation, large- and small-scale fluctuation kinetic energy and integral length scale are analysed in detail. The possible effects of these flow characteristics on the charge stratification and subsequent ignition and combustion processes are also discussed. The results have shown that the strong tumble field was characterized by a very small velocity component in the direction of the tumble rotational axis until the late stage of the compression stroke. The cyclic variation of the bulk flow, though still present, was significantly reduced. Towards the end of the compression process, both low- and high-frequency velocity fluctuations were found to be high after the tumble had collapsed. The velocity fluctuation component along the cylinder axis was characterized by higher frequencies. An integral length scale was found in the range of 4–9 mm during the compression stroke.