The accuracy of acoustic Doppler velocimetry measurements in turbulent boundary layer flows over a smooth bed
The accuracy of acoustic Doppler velocimetry measurements in turbulent boundary layer flows over a smooth bed
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光滑床上湍流边界层流中声多普勒测速测量的准确性
DOI：
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发表时间：
2007
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通讯作者：
J. Crimaldi
中科院分区：
文献类型：
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作者：
D. Dombroski;J. Crimaldi
本文介绍了声学多普勒测速仪（ADV）在近床湍流边界层流动中的应用。与湍流中的最小运动尺度相比，声学仪器具有较大的采样体积。这限制了该技术的准确性，特别是在靠近床或存在大空间梯度的流动中进行测量时。这些局限性进行量化比较ADV的结果，激光多普勒测速仪（LDV）从相同的流量测量，并直接数值模拟类似的流量。在评价中使用了SonTek 16 MHz ADVField系统。测量是在实验室水槽中的光滑床面上的紊流边界层中进行的。该仪器进行了评估，在一个快速和慢速流动的情况下，自由流的速度类似于在许多自然环境中发现的。此外，还报告了ADV样品体积大小和位置的评估结果。平均速度在5%的准确度内，对于快流情况，从床向下至0.7 cm，对于慢流情况，从床向下至1 cm。ADV导出的雷诺应力与LDV导出的雷诺应力在床层1 - 2 cm范围内匹配良好，但在某些情况下，湍流强度明显偏离床层3 - 4 cm。一般来说，错误是最大的接近床，但延伸到更远的床比以前的研究报告。
An evaluation of acoustic Doppler velocimetry (ADV) in the near‐bed region of turbulent boundary layer flows is presented. Acoustic instruments have large sampling volumes compared with the smallest scales of motion in turbulent flows. This limits the accuracy of the technique, especially when making measurements close to the bed or in flows where large spatial gradients are present. These limitations are quantified by comparing ADV results to laser Doppler velocimetry (LDV) measurements from the same flow, and to direct numerical simulations of similar flows. A SonTek 16 MHz ADVField system was used in the evaluation. Measurements were made in a turbulent boundary layer over a smooth bed in a laboratory flume. The instrument was evaluated in both a fast and slow flow case with free stream velocities similar to those found in many natural environments. Additionally, results from an assessment of ADV sample volume size and position are reported. Mean velocities were within 5% accuracy down to 0.7 cm from the bed for the fast flow case and 1 cm for the slow flow case. ADV‐derived Reynolds stresses matched well with those from LDV to within 1‐2 cm of the bed, however turbulence intensities were found to deviate markedly up to 3‐4 cm from the bed in some cases. In general, errors are largest close to the bed, but extend further away from the bed than reported in previous studies.