Abstract

A novel method for three-dimensional particle tracking velocimetry (PTV) is proposed that enables flow measurements in large volumes [\(V=\mathcal {O}(10\) m\({^3}\))] using a single camera. Flow is seeded with centimeter-sized soap bubbles, when combined with suitable illumination, produce multiple glare points. The spacing between the two brightest glare points for each bubble is then utilized to reconstruct its depth. While the use of large soap bubbles comes at the expense of non-Stokesian behaviour, the excellent ray optics allow for large volume illumination when coupled with for instance pulsed LED banks. Possible error sources and the out-of-plane accuracy are discussed before the feasibility of the method is tested in an industrial-scale wind tunnel facility (test section of cross section 9.1 m \(\times\) 9.1 m). In particular, the vortical structure in the wake of a 30%-scale tractor-trailer model at a \(9^{\circ }\) yaw angle is captured in a 4.0 m \(\times\) 1.5 m \(\times\) 1.5 m measurement volume. Long tracks of up to 80 time steps are extracted in three-dimensional space via a single perspective. The successful proof-of-concept confirms the potential of the novel approach for three-dimensional measurements in volumes of industrial scale.

Graphic abstract

中文翻译：

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基于眩光点间距的新型单相机方法进行大规模三维粒子跟踪

摘要

提出了一种新颖的三维粒子跟踪测速法（PTV），该方法可以进行大流量测量[ \（V = \ mathcal {O}（10 \） m \（{^ 3} \））]使用一台相机。流量用厘米大小的肥皂泡播种，再加上适当的照明，会产生多个眩光点。然后，将每个气泡的两个最亮眩光点之间的间距用于重建其深度。尽管使用大肥皂泡会牺牲非斯托克式的性能，但出色的射线光学系统在与脉冲LED库结合使用时可实现大体积照明。在工业规模的风洞设施（横截面的测试部分为9.1 m \（\ times \） 9.1 m）中对该方法的可行性进行测试之前，讨论了可能的误差源和面外精度。特别是，在\（9 ^ {\ circ} \）处30％比例的牵引拖车模型之后的旋涡结构在4.0 m \（\ times \） 1.5 m \（\ times \） 1.5 m的测量空间中捕获偏航角。通过一个透视图，可以在三维空间中提取多达80个时间步长的长轨迹。成功的概念验证证实了在工业规模中进行三维测量的新颖方法的潜力。

图形摘要