风沙流中跃移沙粒冲击速度和角度联合概率分布风洞实验

doi:10.7522/j.issn.1000-694X.2019.00102

摘要/Abstract

摘要： 近地表跃移沙粒速度和角度概率分布是连接风沙运动宏观研究和微观研究的桥梁，对沙粒跃移轨迹和输沙率分布有很大影响。但是，目前跃移沙粒冲击速度概率分布和角度概率分布之间的关系还不明确。使用相位多普勒粒子分析仪（PDPA）测量了风洞沙床面1 mm高度处的跃移沙粒速度，通过分析各冲击速度对应的冲击角度的概率分布研究了沙粒冲击速度和角度的联合概率分布。结果表明：沙粒冲击速度概率分布可用对数正态函数描述，冲击角度概率分布可用指数函数描述；各冲击速度对应的冲击角度都符合指数函数分布，且其衰减速度随冲击速度增加而加快。这表明，冲击速度概率分布和冲击角度概率分布之间具有很强的相关性。最后分别给出了沙粒冲击速度和角度的独立假设概率分布和条件联合概率分布。

关键词: 输沙率, 跃移运动, 沙粒速度, 联合概率分布

Abstract: The velocity distribution of saltating sand grains is the bridge between macroscopic and microscopic aeolian research, which largely affects the saltating trajectory and mass flux profile. However, the relation between probability distribution of impacting speed and that of impacting angle remains unclear. In this paper, velocity of saltating sand grains in wind-blown sand located at 0.001 m above the sand bed was measured using a phase Doppler particle analyzer in a wind tunnel. The joint probability distribution of impacting speed and angle is studied by analyzing the probability distribution of impacting angle under each impacting speed. The results show that the probability distribution of impacting speed can be expressed as a lognormal function, while that of impacting angle follows an exponential function. The probability distribution of impacting angle conditioned for each impacting speed also follows an exponential function, whose slope becomes steeper with increasing impacting speed. This implies that the probability distributions of impacting speed and impacting angle are strongly dependent on each other. In the end, we present functions to describe the independent and conditional joint probability distributions of the impacting speed and angle of saltating sand grains.

Key words: saltating movement, sand speed, joint probability distribution, sand mass flux

中图分类号:

X169

肖锋军, 董治宝, 郭烈锦, 王跃社, 李德标. 风沙流中跃移沙粒冲击速度和角度联合概率分布风洞实验[J]. 中国沙漠, 2020, 40(3): 127-134.

Xiao Fengjun, Dong Zhibao, Guo Liejin, Wang Yueshe, Li Debiao. Experimental study on the joint probability distribution of impacting speed and angle of saltating sand grains in a wind tunnel[J]. Journal of Desert Research, 2020, 40(3): 127-134.

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