影像方法於量測顆粒流速度場之應用

Applications of image methods for the measurement of granular flows

李健誌(Chien-Chih Li)

指導教授 ： 戴義欽

國立暨南國際大學/科技學院/土木工程學系/碩士(2007年)

https://doi.org/10.6837/NCNU.2007.00051

摘要

顆粒材料的流動包含流體與固體的特性。為了充分瞭解顆粒流的行為，本研究使用粒子追蹤測速法量測實驗中顆粒的速度。
為了提高粒子追蹤測速法的準確度，本研究分析各實驗照片之特性來調整粒子追蹤測速法的參數以及比對方法。主要採取的步驟為，校正所拍攝到之圖片，並且使用影像方法強化顆粒中心與背景之差異。利用此差異取得顆粒中心後，藉由顆粒的幾何形狀與排列方式排除非觀測平面之顆粒。顆粒配對的部份則是使用星形比對為主要概念，本研究透過改變配對星形的分支數目與計算方式，來達到精確的星形比對效果，而藉由使整體星形比對差異最小，來決定顆粒配對結果。最後經由顆粒中心座標以及配對結果，加上影像取得之間隔與比例尺求出顆粒流之速度場。
本研究將粒子追蹤測速法應用於旋轉流槽實驗、曲坡面流槽實驗與傳遞波實驗，藉由粒子追蹤測速法量測實驗中顆粒流之速度。在旋轉流槽實驗中計算出自由液面以及顆粒垂直與水平方向的速度。在曲坡面流槽實驗中獲得流體推動顆粒瞬間的速度。而傳遞波實驗則成功量測出顆粒流與傳遞波之速度。

關鍵字

粒子追蹤測速法 ； 粒子影像測速法 ； 顆粒流

並列摘要

Granular materials exhibit both fluid and solid behaviors, which exhibit the complexity of this problem. For a more detailed investigation, this study is devoted to digital imaging methods, the Particle Tracking Velocimetry (PTV) technique, for measuring the velocity field of granular flows. The methods include image processing, particle identification, particle matching, trajectory reconstruction, spatial and temporal filtering. After the image processing, the identified particle centers in two time sequential pictures are matched by the concept of star-match algorithm. By virtue of the time interval and movement of the particles between the pictures the velocity can therefore be computed. In this study the accuracy has been improved by analyzing the picture characteristics and changing the branch number of the star-match figure.
The developed PTV technique has been applied to the measurement of experiments of rotating drums, convex and concave channel, and traveling shock waves. We computed the free surface and the vertical and horizontal speeds of granular materials in rotating drums. In the experiment of convex and concave channel, the moving boundary and velocities of fluid-granular solid mixture have been well measured. The traveling shock wave and velocity evolution have also been investigated by the PTV method for dry Ottawa sands fast flowing in a straight channel.

並列關鍵字

Particle Image Velocimetry ； Particle Tracking Velocimetry ； granular flow

參考文獻

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