Influence of time interval between particle images on the measurement accuracy of stereoscopic PIV
CHEN Qigang1, ZHONG Qiang2
1. School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China; 2. College of Water Resources&Civil Engineering, China Agricultural University, Beijing 100083, China
Abstract：Stereoscopic particle image velocimetry (SPIV) measures planar three-dimensional velocity fields through the use of at least two pairs of particle images recorded separately by two different cameras. The measurement accuracy is closely related to the time interval between particle images. Two data sets for a laminar flow field and a turbulent open channel flow field were used to investigate the influence of the time interval on the SPIV measurement accuracy. The results show that when the one-quarter rule is satisfied, the overall measurement accuracy for laminar flow improves with increasing time interval. However, larger time intervals lead to lower measurement accuracies in regions with large velocity gradients when the particle displacement in the interrogation window does not satisfy the two-thirds rule. For the turbulent open channel flow, the measurement accuracy in the outer region changes little with the time interval, but the errors in the near-wall region increase greatly with increasing time interval when the two-thirds rule is not satisfied. For both flows, the measurement errors increase when the one-quarter rule is not satisfied. Thus, the one-quarter rule must always be satisfied and a relatively long time interval will improve the measurement accuracy for flows with negligible velocity gradients. Finally, the longest time interval satisfying the two-thirds rule is the optimum choice for measuring flows with large velocity gradients.
陈启刚, 钟强. 粒子图像时间间隔对体视PIV测量误差的影响[J]. 清华大学学报（自然科学版）, 2020, 60(10): 864-872.
CHEN Qigang, ZHONG Qiang. Influence of time interval between particle images on the measurement accuracy of stereoscopic PIV. Journal of Tsinghua University(Science and Technology), 2020, 60(10): 864-872.
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2020, Vol. 60 
