Development of measurement method for investigating three dimensional turbulence structures in liquid-slid flow

这项研究的目的是发展一种测量技术，以了解液-固两相流中的三维湍流结构。本研究包括两个过程：一是对武原开发的超分辨率PIV在时间分辨率上的改进；二是对渡边开发的三维立体PIV在空间分辨率上的改进。虽然超分辨率PIV可以通过使用多个粒子示踪器进行可视化来测量高空间分辨率的流场，但由于我们没有足够的捕获系统，它没有足够的时间分辨率。在这项科研基金的大力帮助下，购买了一套高分辨率、宽范围的高速视频系统，解决了这一问题。利用该高速摄像系统，采集了多孔体内部及附近的流场图像。并详细研究了多孔体内部和下游区域湍流的产生和衰减机理。…此外，虽然三维立体PIV可以测量三维流动结构，但如果在流体中加入大量的粒子示踪剂，则需要投入大量的时间进行分析。通过改进计算算法，克服了这一问题。将三维立体PIV重建为具有高空间分辨率的PIV系统。将改进的三维PIV应用于破碎带下的多相流。结果表明，改进的三维立体PIV是测量破碎波作用下复杂流体流动和泥沙运动的有效工具，并发展了一种新的图像测速仪--路径线连接测速仪，用于测量具有三维结构的高速流体运动和强湍流的液-固两相流。将“路径线连接测速仪”应用于颗粒运动诱导的流场测量。结果表明，路径线连接测速仪是测量高浓度颗粒和水面多相流的一种非常有用的工具。较少

The aim of this study is to develop a measurement technique for understanding three dimensional turbulence structures in liquid-solid flows. This study is composed of two processes ; one is for improvement of Super Resolution PIV developed by Takehara on time resolution and the other is for improvement of 3-D stereo PIV developed by Watanabe on space resolution.Although the super resolution PIV can measure the flow field with high space resolution by using many particle tracers for visualization, it did not have enough time resolution because we did not have enough capturing system. This problem was overcome by purchasing a high-speed video system with high resolution and wide range with great help of this scientific research fund. By using this high-speed video system the images of flow fields inside and in the vicinity of a porous body were captured. And generation and decay mechanisms of turbulence flow inside the porous body and in the downstream region have been studied in detail. … More Although the 3-D stereo PIV can measure the three dimensional flow structures, it needed a great investment of time to analyze if many particle tracers were seeded in fluid. This problem was overcome by improving calculation algorism. As a result the 3-D stereo PIV was reconstructed as a PIV system with high space resolution. The improved 3-Dstereo PIV was applied to a multi-phase flow under the breaking zone. It has been found that the improved 3-D stereo PIV is a useful tool for measurement of complex fluid flow and sediment motion under breaking waves.Furthermore, a new image velocimetry, called "path line connecting velocimetry", has been developed for measurement of the liquid-solid flows with high speed fluid motion and strong turbulence with three dimensional structure. The "path line connecting velocimetry" has been applied to the measurement of the flow field induced by particle motion. As a result, it was shown that the path line connecting velocimetry is a very useful tool for measurement of multi-phase flows including particles with high concentration and water surface. Less