We describe the design and performance of a novel optical measurement system that can be used for measuring vortex-induced vibrations (VIV) of long flexible cylinders. We believe this is the first time this technology has been used to measure VIV in a long flexible cylinder. The emphasis is given to the measurement technique itself. It can be used either in air or in water and we believe it is a better alternative to other traditional vibration response measurement techniques used to study VIV in the laboratory. The measurement system is based on the Defocusing Digital Image Particle Velocimetry (DDPIV) concept, proposed by Willert and Gharib in [l]for measuring velocity flow fields. A set-up, which was built to conduct vortex-induced vibration measurements in a wind tunnel facility with a cross-section of 1.8 x 1.2 m, has been used in a laboratory to demonstrate the capabilities of the optical measurement system when known displacements are produced in the mappable or measurement volume. The same supporting structure designed to provide su-port for the cylinder models inside the wind tunnel test section, has been used to hold a target which has been move to different known locations to measure the performance of the system. The design, description and performance of the measurement technique are discussed.
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机译:我们描述了一种新型光学测量系统的设计和性能,该系统可用于测量长形柔性圆柱体的涡激振动(VIV)。我们相信,这是该技术首次用于测量长柔性圆柱体中的VIV。重点是测量技术本身。它既可以在空气中也可以在水中使用,我们相信它是用于研究实验室VIV的其他传统振动响应测量技术的更好替代方案。测量系统基于Willert和Gharib在[1]中提出的用于测量速度流场的散焦数字图像颗粒测速(DDPIV)概念。在实验室中使用的装置用于在横截面为1.8 x 1.2 m的风洞设施中进行涡流诱发的振动测量,已在实验室中用于证明当已知位移为零时光学测量系统的功能。在可映射或测量体积中生成。设计用来为风洞测试区内部的气缸模型提供支撑的相同支撑结构已用于固定目标,该目标已移至不同的已知位置以测量系统的性能。讨论了测量技术的设计,描述和性能。
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