Hot-wire spatial resolution effects in measurements of grid-generated turbulence
Hot-wire spatial resolution effects in measurements of grid-generated turbulence
复制标题
网格生成湍流测量中的热线空间分辨率效应
DOI：
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发表时间：
2012
期刊：
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通讯作者：
A. Smits
中科院分区：
文献类型：
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作者：
A. Ashok;S. Bailey;M. Hultmark;A. Smits
我们使用网格生成的湍流作为基准流来测试空间分辨率对热线湍流测量的影响。为了量化的空间滤波，湍流统计和光谱下游的网格的测量，使用不同长度的热线和比较的结果，从一个新的纳米级热风速仪探头，它具有感测长度的顺序，或小于，柯尔莫哥洛夫尺度。为了分离时间和空间滤波的影响，进行了一项研究，以确保数据没有时间滤波的伪影，以便测量结果的差异可以完全归因于空间滤波。由于空间滤波的流向雷诺应力的衰减的经验相关性的构建，它表明，这些网格湍流的结果直接关系到近壁区域的壁有界的流动，空间滤波的影响是最尖锐的感觉。观察到的流向谱函数的空间滤波的效果延伸到几乎所有的波数，即使是那些显着低于热线本身的长度。它还表明，估计的Kolmogorov尺度的空间滤波的影响时，导线长度比Kolmogorov长度被使用。
We use grid-generated turbulence as a benchmark flow to test the effects of spatial resolution on turbulence measurements with hot wires. To quantify the spatial filtering, measurements of the turbulence statistics and spectra downstream of the grid were made using hot wires of varying length and compared to the results from a new nanoscale thermal anemometry probe, which has a sensing length of the order of, or smaller than, the Kolmogorov scale. In order to separate the effects of temporal and spatial filtering, a study was performed to ensure that the data were free of the artifacts of temporal filtering so that differences in the measurements could be wholly attributed to spatial filtering. An empirical correlation for the attenuation of the streamwise Reynolds stress due to spatial filtering is constructed, and it is shown that these grid turbulence results relate directly to the near-wall region of wall-bounded flows, where the effects of spatial filtering are most acutely felt. The effect of spatial filtering on the streamwise spectrum function is observed to extend to almost all wavenumbers, even those significantly lower than the length of the hot wire itself. It is also shown that estimates of the Kolmogorov scale are affected by spatial filtering when wires longer than the Kolmogorov length are used.