摘要
为了探究风沙流起动过程中沙粒输运特征,利用PTV测量技术在风洞中对风沙流起动过程进行了测量,分析了沙粒空间分布、沙粒平均水平速度、输沙率、沙粒数密度和输沙通量随时间的变化规律。结果表明:风沙流起动时间大约为1.5s。起动过程中,输沙率随时间迅速增加,气流中沙粒总数目随时间的变化可表示为指数函数,沙粒数密度和输沙通量随高度的变化均可近似表示为负指数衰减函数。在t=1.0s时刻的沙粒平均水平速度大于相同高度处以后时刻的沙粒平均水平速度,同一高度处t=1.5s以后的沙粒数密度大于t=0.5s、1.0s时刻的沙粒数密度,同一高度处t=1.5s以后的输沙通量大于t=1.0s时刻的输沙通量。沙粒数密度随高度的衰减率一般随时间的增加而减小,并在t=1.5s后逐渐接近稳定值。
In order to further explore the characteristics of sand transport during the initiation process of aeolian sand transport,the developing process of initiation of aeolian sand transport was measured by PTV（particle tracking velocimetry）technology in a wind tunnel.The variation of particle space distribution,the horizontal particle velocity,sand transport rate,particle number density and sand flux with time is analyzed.The result shows that the time consumption is about 1.5 s for the initiation process of aeolian sand transport.During the initiation process,the sand transport rate increases rapidly with time,the total particle number in air increases exponentially with time,and the variation of both particle number density and sand flux with height can be approximately expressed by a negative exponential function.At the same height,the mean horizontal particle velocity at t=1.0 s is larger than that after this time,the particle number density after t=1.5 s is larger than that at t=0.5 s and 1.0 s,and the sand flux after t=1.5 s is more than that at t=1.0 s.The decay rate of particle number density with height generally decreases with time,and approximates to a constant after t=1.5 s.
出处
《中国沙漠》
CSCD
北大核心
2017年第6期1051-1058,共8页
Journal of Desert Research
基金
国家自然科学基金项目(41330746
41271020)
关键词
风沙流
起动
风洞实验
aeolian sand transport
initiation
wind tunnel experiment
