Two-dimensional fluid-velocity measurements by use of digital-speckle correlation techniques
Two-dimensional fluid-velocity measurements by use of digital-speckle correlation techniques
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DOI：
10.1007/bf02324993
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发表时间：
1984-06
影响因子：
2.4
通讯作者：
Z. He;Michael A. Sutton;W. Ranson;W. Peters
中科院分区：
文献类型：
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作者：
Z. He;Michael A. Sutton;W. Ranson;W. Peters
1970年激光散斑技术应用于测量可变形介质中的位移，随后是基础理论工作2-7和各种方法的广泛应用2-7然而，直到20世纪70年代末S，研究人员才开始将散斑技术应用于流体速度的测量。用来测量流体速度8-3的最常见的实验方法在概念上很简单，可以描述如下。液体中加入分散介质(如聚苯乙烯微球、乳胶漆、玻璃珠等)。并且启动流型。用一片激光照射选定的流场横截面。使用摄像系统在一张胶片上记录两幅已知时间滞后的由种子粒子散射的光的图像，然后将胶片处理为双曝光散斑图，以获得二维位移场。利用两幅图像之间的已知时间差，将这些位移场转换为速度场。上述方法的主要缺点是需要相当长的时间来完成数据简化。然而，最近提出了一种利用随机图案同时获得位移和位移梯度的计算机方法。该方法已被用于分析固体中的刚体运动和单轴应变。这项工作提出了一种基于计算机的方法来确定定常层流流体中的二维速度分布。结果表明，计算机系统是测量相对较小的流体速度的一种可行的工具，特别是因为所有的数据归算都是由计算机和适当的软件完成的。实验概述
The advent of laser-speckle techniques applied to the measurement of displacements in deformable media'in 1970 was followed by both basic theoretical work 2-~ and a wide variety of applications of the various methods2-7 However, it was not until the late 1970's that researchers began to apply speckle methods to the measurement of fluid velocities. The most common experimental procedure utilized to measure fluid velocities 8-~ 3 is simple in concept and can be described as follows. The fluid is seeded with a scattering medium (eg, polystyrene spheres, latex paint, glass beads, etc.) and the flow pattern is initiated. A sheet of laser light is used to illuminate a chosen cross section of the flow field. A camera system is used to record two images of the light scattered by the seeded particles, with a known time lag, on one piece of film, The film is then processed as a double-exposure specklegram to obtain two-dimensional displacement fields. These displacement fields are converted to velocity fields by use of the known time differential between the two images. A major disadvantage of the method described above is that considerable time is required to complete the data reduction. Recently, however, a computer-based method for obtaining both displacements and displacement gradients using random patterns was proposed." The method has been used to analyze both rigid-body motions" and uniaxial strains in a solid." This work presents an application of this computer-based method to the determination of two-dimensional velocity distributions in a fluid undergoing steady, laminar flow. The results indicate that the computer-based system is a viable tool for the measurement of relatively small fluid velocities, especially since all of the data reduction is completed by use of a computer and appropriate software.Experiment--General Overview