Simultaneous two-scale 3D-PTV measurements in turbulence under the influence of system rotation
Simultaneous two-scale 3D-PTV measurements in turbulence under the influence of system rotation
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DOI：
10.1007/s00348-010-1026-6
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发表时间：
2011-07
影响因子：
2.4
通讯作者：
M. Kinzel;M. Wolf;M. Holzner;B. Lüthi;C. Tropea;W. Kinzelbach
中科院分区：
文献类型：
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作者：
M. Kinzel;M. Wolf;M. Holzner;B. Lüthi;C. Tropea;W. Kinzelbach
我们提出了一种能够以拉格朗日方式以两种不同的空间分辨率同时测量流速的三个分量的技术。我们使用两个配备过滤器的同步 3D 粒子跟踪测速 (3D-PTV) 系统来分离两种类型的种子粒子，并分别测量 55 × 55 × 50 mm3 和 15 × 15 × 15 mm3 的体积。通过这种方式，我们获得（a）大观测体积中的速度场，重点关注大尺度流动特征；（b）小观测体积中的速度导数，提供与涡度和应变相关的小尺度量。小观测体位于大观测体的中心，这使得小尺度量与大尺度流动模式相关。为了说明同步两尺度 3D 粒子跟踪测速 (STS 3D-PTV) 方法的能力，分析了系统旋转影响下无剪切湍流中的涡度和应变行为。我们发现，在准二维区域，涡旋拉伸仅在柱状涡旋管内部受到强烈抑制。
We present a technique capable of measuring in a Lagrangian manner the three components of the flow velocity simultaneously at two different spatial resolutions. We use two synchronized 3D Particle Tracking Velocimetry (3D-PTV) systems equipped with filters to separate the two types of seeding particles and measure in volumes of 55 × 55 × 50 mm3and 15 × 15 × 15 mm3, respectively. In this way, we obtain (a) the velocity field in a large observation volume with focus on the large-scale flow features and (b) velocity derivatives in a small observation volume providing small-scale quantities associated with vorticity and strain. The small observation volume is located in the center of the large one, which allows the small-scale quantities to be related to the large-scale flow patterns. To illustrate the capability of the simultaneous two-scale 3D Particle Tracking Velocimetry (STS 3D-PTV) method, the behavior of vorticity and strain is analyzed in shear-free turbulence under the influence of system rotation. We find that in the quasi-2D region, vortex stretching is strongly suppressed only inside columnar vortex tubes.