Velocity measurement inside a diesel spray by using time-resolved PIV under high ambient density condition
Velocity measurement inside a diesel spray by using time-resolved PIV under high ambient density condition
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在高环境密度条件下使用时间分辨 PIV 测量柴油喷雾内的速度
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
M. Arai
中科院分区：
文献类型：
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作者：
Y. Zama;Wataru Ochiai;T. Furuhata;M. Arai
在直喷柴油机中，为了提高发动机的性能，其增压压力有增大的趋势。高增压压力导致发动机气缸内气体密度增大，高气体密度影响柴油机的喷雾行为和燃油与空气的混合气形成。因此，在高气体密度条件下，需要精确地研究喷雾行为。本文采用时间分辨粒子图像测速技术（PIV）对柴油喷雾内部的速度场进行了测量，以了解高气体密度环境下的喷雾行为。研究了不同环境气体密度和注入压力下的速度分布。结果表明，在高气体密度环境下，靠近喷雾外围的喷雾液滴簇几乎不移动，并被重新夹带到主喷雾流中。这些现象与喷雾外围附近涡的形成相耦合。此外，从归一化轴向速度分布可以看出，随着环境气体密度和喷射压力的增加，Z = 40mm处的强混合区位置从喷雾外围向内部转移。但在Z=60mm处，归一化轴向速度分布不出现这种趋势。
In a direct injection diesel engine, its boost pressure tends to increase for improvement of engine performance. High boost pressure resulted in an increase of gas density in engine cylinder, and the high gas density affected the diesel spray behavior and mixture formation of fuel and air. Therefore, under high gas density condition, precise investigation of spray behavior was required. In this paper, in order to understand spray behavior in high gas density surroundings, velocity field inside a diesel spray was measured with time-resolved particle image velocimetry (PIV). Velocity distributions were investigated with various ambient gas densities and injection pressures. As the results, in high gas density surroundings, cluster of spray droplets near the spray periphery hardly moved, and it was re-entrained into main spray flow. These phenomena were coupled with vortex formation near the spray periphery. Moreover, from normalized axial velocity distribution, it was clear that the position of intense mixing zone at Z = 40mm shifted from the periphery to the inside of spray with increasing ambient gas density and injection pressure. However, its trend did not appear for normalized axial velocity distribution at Z=60mm.