Turbulence generator using a precessing sphere
Turbulence generator using a precessing sphere
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DOI：
10.1063/1.2746040
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发表时间：
2007-06
影响因子：
4.6
通讯作者：
S. Goto;Nobukazu Ishii;S. Kida;M. Nishioka
中科院分区：
文献类型：
--
作者：
S. Goto;Nobukazu Ishii;S. Kida;M. Nishioka
我们提出了一个旋进球作为桌面湍流发生器，它具有较小的不确定性，在控制参数的设置和由此产生的高流量再现性。进动是通过使球体的自旋轴围绕另一轴（进动轴）旋转来实现的。在我们的实验中，两个轴固定成直角。球体内部的流动仅由两个无量纲参数控制，一个是Re（由围绕旋转轴的最大圆周速度定义的雷诺数），另一个是Γ（进动率）。通过对粒子图像测速仪测量的速度场进行时间序列分析，揭示了维持湍流的参数范围。当Re超过几千时，甚至对于百分之几数量级的Γ，发展良好的湍流也能维持。
We propose a precessing sphere as a tabletop turbulence generator, which has less uncertainty in the setting of control parameters and the resulting high flow-reproducibility. The precession is realized by rotating the spin axis of a sphere around another axis (the precession axis). In our experiments, the two axes are fixed at right angles. The flow inside the sphere is governed only by two nondimensional parameters, one being Re (the Reynolds number defined by the maximum peripheral velocity around the spin axis) and the other being Γ (the rate of precession). The range of parameters for sustaining turbulence is revealed by the time-series analysis of velocity fields measured by particle image velocimetry. Well-developed turbulence can be sustained even for Γ of the order of a few percent when Re is beyond a few thousands.