Development of Image Measurement System for High Velocity Flow Field

本研究项目的主要目的是开发一种利用可控机械快门的新闻图像速度场测量系统，并开发一些分析方法。本研究采用了相关法等两幅时序图像进行分析的方法。在研究过程中，当然也进行了几点应用和一些考虑。结果表明：(1)从实用角度看，机械快门系统适用于对激光光片的控制，而不是所谓的黑池。(2)快门控制在1/000秒是可能的。该系统不仅可以测量2.0-3.0m/S的流速，还可以通过控制成像范围来测量更高的速度场。(3)本系统采用了目前最流行的NTSC图像信号。这意味着我们可以使用普通的CCD摄像机和录像机系统。为了将该系统应用于大型循环水风洞，必须研制出特殊的示踪剂颗粒。其中一种可能的方法是使用微胶囊。(5)提出了一种基于统计分析的新方法。这使得利用图像数据直接测量时均速度场成为可能。(6)介绍了激光系统在波高测量、壁面摩擦测量等方面的应用。

Main purpose of this research project is developing a news image measurement system for velocity field using controllable mechanical shutter, and also developing some analysis methods. In this research, the method in which two time sequential images are used for the analysis such as correlation method is employed. During the research, the several applications and some consideration are of course made. The followings are the results.(1) Mechanical shutter system is suitable for the control to the laser light sheet, rather than the so-called black cell, from the practical view point.(2) It is possible to control the shutter as 1/000 sec. This enables to measure the flow with 2.0 - 3.0 m/s. And also it is possible to measure a more high velocity field by controlling the rage of image.(3) In this system, the most popular NTSC signal for the image data is used. This means that we can use the normal CCD camera and VTR system. This is important for the practical system.(4) In order to use the system in a large circulating water tunnel, the special tracer particle should be developed. One of the possible method is using micro-capsule.(5) A new approach using statistical analysis is developed here. This enables to measure the time-mean velocity field using image data directly.(6) Some of the application using laser system are shown such as wave height measurement and wall friction measurement.