风沙流中沙粒旋转对PIV测量结果的影响

摘要/Abstract

摘要： 基于粒子图像测速仪(Particle Image Velocimetry, 简称PIV)测速度原理以及测量颗粒粒径原理,分析了经过一个激光脉冲时间前后CCD拍摄到的两帧沙粒二维图像,计算了沙粒因旋转而导致的沙粒质心位移与成像中点位移的差别以及不同时刻成像面的大小,导出PIV测量不规则旋转沙粒速度和粒径的测量误差公式。结果表明,PIV测速误差与沙粒速度有关,速度越大测速误差越小,最大测速误差不超过10％,可通过增大激光脉冲时间间隔以减小PIV的测速误差;由于沙粒旋转,使得不同时刻PIV测量到的同一个不规则沙粒的粒径也可能不同,其差别由沙粒形状的不规则程度决定,并指出PIV测量风沙流中不规则沙粒的粒径的可行性与可靠性需要进一步论证。

关键词: 粒子图像测速仪（PIV）, 不规则沙粒, 角速度, 测量误差

Abstract: In this paper, based on the measurement principle of particle image velocimetry (PIV), we analyze the measurement error of PIV. For two frame images of a single sand particle taken by charge-coupled device (CCD) camera at an interval of a pulse time, we calculate the displacement of the mass center of the sand particle and the displacement of the center of image, and calculate the difference between the displacements of the two centers. Then we derive the error's formulas of sand particle velocity and sand particle diameter measurement used by PIV due to the sand particle rotation. It indicates that the velocity error measured by PIV relates to the velocity of sand particles, and the higher is the velocity of sand particles, the larger is the error. The maximum error of velocity measurement by PIV is not beyond 10%, and the measurement error can be decreased by increasing the pulse time. For a single irregular sand particle, the diameters measured by PIV at different moment are not same due to the rotation of sand particles, and the differences among the measurement errors of particle diameters depend on the sand shapes. For lager sand particle, it is pointed out that there is a long way to validate diameter measurement.

Key words: Particle image velocimetry(PIV), irregular sand particle, angular velocity, measurement error

中图分类号:

X169

严杰;谢莉*. 风沙流中沙粒旋转对PIV测量结果的影响[J]. 中国沙漠, 2011, 31(3): 607-612.

YAN Jie;XIE Li. Influence of Rotation Rate of Sand Particles on Measurement Results by PIV in Wind Sand Flux[J]. JOURNAL OF DESERT RESEARCH, 2011, 31(3): 607-612.

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