Experimental detection of deterministic turbulence
Experimental detection of deterministic turbulence
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DOI：
10.1080/14685248.2011.573792
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发表时间：
2011-01
影响因子：
1.9
通讯作者：
V. Borodulin;Y. Kachanov;A. P. Roschektayev
中科院分区：
文献类型：
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作者：
V. Borodulin;Y. Kachanov;A. P. Roschektayev
本文对完全可控的三维宽带扰动引起的转捩和湍流转捩后边界层进行了实验研究。具有逆压梯度的自相似层流边界层被用作基本流。激发的受控扰动最初代表Tollmien-Schlichting（TS）波，它具有在小和中等时间尺度上随机的谱分量，但在非常大的时间尺度上具有周期性，在此期间，流动多次通过实验模型。详细的测量进行了通过热线风速仪在一个广泛的空间区域开始阶段的小振幅不稳定波和结束阶段的发展后过渡湍流。结果发现，所产生的后过渡流的平均特性对应于发展的壁湍流;同时，瞬时流结构仍然保持确定性，即从一个长信号实现到另一个长信号实现基本上是可再现的。这种瞬时结构进行了详细测量，并与已知的一个从以前的调查湍流和过渡流。结果表明，确定性（可再现性）壁湍流在自然界中确实存在，并且可以通过实验在边界层中产生。这一结果除了具有重要的哲学意义外，还为后来的湍流研究提供了一个非常有力的方法论工具。
This paper is devoted to an experimental investigation of transitional and turbulent, post-transitional boundary layer initiated by fully controlled 3D broadband perturbations. A self-similar laminar boundary layer with an adverse pressure gradient was used as a primary base flow. The excited controlled disturbances initially represented Tollmien–Schlichting (TS) waves, which had a spectral component that was random at small and moderate time scales but periodical at very large time scales, during which the flow passed the experimental model several times. Detailed measurements were carried out by means of a hot-wire anemometer in a broad spatial region starting with stages of small-amplitude instability waves and ending with stage of a developed post-transitional turbulent flow. It was found that average characteristics of the produced post-transitional flow corresponded to the developed wall turbulence; meanwhile, the instantaneous flow structure there still remained deterministic, i.e. basically reproducible from one long signal realization to another. This instantaneous structure was measured in detail and compared with the one known from previous investigations of turbulent and transitional flows. A conclusion was drawn that the deterministic (reproducible) wall turbulence did exist in nature and could be generated experimentally in boundary layers. Besides important philosophical meaning, this result provided investigators with a very powerful methodological tool for subsequent turbulence research.