Determination of the measuring position in laser-Doppler anemometry
Determination of the measuring position in laser-Doppler anemometry
复制标题
激光多普勒风速测量中测量位置的确定
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
J. Jovanović
中科院分区：
文献类型：
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作者：
F. Durst;R. Müller;J. Jovanović
本文涉及确定激光多普勒风速计（LDA）相对于墙壁的测量位置。所提出的方法基于以下发现：当安装在与墙壁平行的静态空气中的电线距离墙壁小于 800 μm 时，热线风速计的输出会增加。对于给定的热线风速计参数，热线风速计输出电压取决于墙壁材料以及电线与墙壁的距离。对测试部分的壁材料进行适当校准后，可以使用测试装置中的风速计读数来找到电线位置。通过导线移动 LDA 系统的测量体积会产生 LDA 光电倍增管的输出电压变化，呈现高斯形状。当达到最大输出电压时，测量控制体积的中心位于导线的中心，因此LDA测量位置的位置是已知的。然后，使用 LDA 遍历系统的比例尺相对于该点进行 LDA 系统的所有位置测量。如果通过采用折射率匹配液体消除透明测试部分墙壁的光学效应，则还有其他方法可以找到激光多普勒风速计相对于墙壁的测量位置。本文描述了一种这样的方法及其在管道近壁湍流研究中的应用。
The present paper is concerned with the determination of the measuring position of a laser-Doppler anemometer (LDA) relative to a wall. The proposed method is based on the finding that the output of a hot-wire anemometer increases when the wire, which is mounted in quiescent air parallel to the wall, is brought closer than 800 μm to the wall. For given hot-wire anemometer parameters, the hot-wire anemometer output voltage depends on the wall material and the wire distance from the wall. After suitable calibration for the wall material of the test section, the anemometer reading in a test rig can be used to find the wire position. Moving the measuring volume of a LDA-system across the wire yields an output voltage variation of the LDA-photomultiplier showing a Gaussian shape. When the maximum output voltage is reached, the centre of the measuring control volume is located at the centre of the wire and, hence, the location of the LDA-measuring position is known. All position measurements for the LDA-system are then taken relative to this point using the scale of the LDA-traversing system. If optical effects of transparent test section walls are eliminated by employing refractive index matched liquids, there are other ways to find the measuring position of a laser-Doppler anemometer relative to a wall. One such method and its application to the study of the turbulent near wall flow in a pipe is described in this paper.