THE EFFECT OF SAMPLE SIZE , TURBULENCE INTENSITY AND THE VELOCITY FIELD ON THE EXPERIMENTAL ACCURACY OF ENSEMBLE AVERAGED PIV MEASUREMENTS
THE EFFECT OF SAMPLE SIZE , TURBULENCE INTENSITY AND THE VELOCITY FIELD ON THE EXPERIMENTAL ACCURACY OF ENSEMBLE AVERAGED PIV MEASUREMENTS
复制标题
样本大小、湍流强度和速度场对集合平均PIV测量实验精度的影响
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
C. Camcı
中科院分区：
文献类型：
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作者：
O. Uzol;C. Camcı
本文对交错排列的两排圆柱近尾流的PIV数据进行了统计分析，研究了样本大小、湍流强度和速度场对整体平均数据的影响。在尾流内下游两个直径处进行PIV测量。使用700个矢量图获得系综平均速度场。实验是在雷诺数为10000的情况下进行的，实验是基于进口速度和气缸直径。为了统计分析的目的，分别收集了2750张矢量地图。对于沿沿着y轴的测量点的线，在域的中间部分，获得了速度矢量的两个分量的统计平均值和方差随样本大小的变化。湍流强度水平沿着这条线在30- 70%之间变化。速度矢量的x和y分量分别在0.88-5.4 m/s和0-0.6 m/s之间变化。使用2750个样本的总数，计算每个测量点的100个随机选择的5、10、25、50、100、250、500、750和1000个集合的统计独立平均值。每个样本大小的平均值周围的散射取决于当地的湍流强度水平和当地的速度大小。结果表明，湍流强度越大，平均数据的误差越大，而速度幅值越小，平均数据的误差越大。
A statistical analysis of the PIV data, obtained inside the near wake of a staggered 2-row array of circular cylinders, is performed for the investigation of the effect of sample size, turbulence intensity and the velocity field on the ensemble-averaged data. The PIV measurements are performed at two diameters downstream inside the wake. The ensemble averaged velocity field is obtained using 700 vector maps. The experiments are conducted for a Reynolds number of 10000 based on the inlet velocity and the cylinder diameter. For statistical analysis purposes, 2750 vector maps are collected separately. Variations of the statistical means and variances with sample size for the two components of the velocity vector are obtained for a line of measuring points along y axis at the mid-section of the domain. The turbulence intensity levels vary between 30-70 % along this line. The x and y components of the velocity vector vary between 0.88-5.4 m/s and 0-0.6 m/s, respectively. Using the total number of 2750 samples, 100 randomly selected statistically independent averages of 5, 10, 25, 50, 100, 250, 500, 750 and 1000 ensembles are calculated for each measuring point. The scattering around the mean value for each sample size depends on both the local turbulence intensity level and the local magnitude of the velocity. It is concluded that the errors in the ensemble averaged data increase not only with the increasing turbulence intensity levels but with the decreasing velocity magnitude as well.