流體對可侵蝕傾斜床夾帶運移行為之研究

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題名:	流體對可侵蝕傾斜床夾帶運移行為之研究
作者:	李育誠;Li, Yu-Cheng
貢獻者:	機械工程學系
關鍵詞:	顆粒;可傾斜流槽;侵蝕;沉積;流量;傾斜角;avalanche;inclined channel;erosion;deposition;flow rate;tilt angle
日期:	2022-08-29
上傳時間:	2022-10-04 12:15:13 (UTC+8)
出版者:	國立中央大學
摘要:	隨著近年全球氣候的不穩定的變化，世界各地頻頻傳出，因為強大的風雨造成的坡地災害，當土石的顆粒受到內外營力作用時，發生劇烈的崩塌流動行為時，亦會對在原坡度上的表面土石進行侵蝕及夾帶現象，此現象會造成坡地的災害越加嚴重。對於自然環境與人類社會造成生態、自然環境、經濟、生命安全的嚴重損失。為此本研究透過實驗的形式，觀察顆粒崩塌的流動行為。本研究主要是透過實驗來探討當不同傾斜坡度與水流量對於顆粒床層的崩塌並針對侵蝕與沉積現象進行討論。實驗透過建置開放式二維傾斜流槽，利用手動調整流槽中的傾斜角度並以PLC 控制入水的流量大小，使水流進入傾斜的顆粒床層區。實驗使用的顆粒是用4mm 白色的氧化鋁珠，透過高速攝影機拍攝後進行影像處理來分析顆粒在流槽中的流動現象並使用PIV 分析流體流動時的速度場分布觀察固液兩相中的流動。實驗結果主要分析了侵蝕床與沉積床部分，分別是顆粒體受到水流影響後對於侵蝕床中的侵蝕面積大小、侵蝕深度、侵蝕的距離隨時間的變化和沉積床中顆粒體受到水流夾帶後將顆粒體搬移至沉積床的沉積面積隨時間變化，沉積深度在不同流槽位置的變化關係。並透過最終侵蝕面積分析了不同傾斜角及流量影響下的分布情形與侵蝕率比較，還闡述無因次化最終的侵蝕面積與位能損失關係圖，並以指數函數進行分布關係的擬合。由實驗的結果得知，當水流量及傾斜角越大時，皆會對可侵蝕顆粒床與沉積都會有顯著的改變，當水流量越大時對於侵蝕的面積與沉積面積都是呈現正相關的分布。這是由於水流量的變化會影響顆粒體間原有的摩擦阻力，使顆粒原有的結構受到破壞進而導致嚴重的侵蝕與夾帶效應，進而影響沉積床中的沉積面積分布。由侵蝕的距離與流槽中不同位置的侵蝕深度分布發現，當水流量與傾斜的增加也會使侵蝕的作用越加的明顯。而由顆粒床中的侵蝕率與位能損失變化發現，當傾斜角越大時對於能量的損失會越加的劇烈。;With the unstable changes in the global climate in recent years, natural disasters have been frequent reports from all over the world. Because of the slope disaster caused by strong wind and rain, when the soil and rock particles are subjected to internal and external forces, the violent collapse and flow behavior will also affect the original slope. Erosion and entrainment of the surface soil and rock on the surface will cause more serious disasters on slopes. It has caused serious losses to the natural environment and human society in terms of ecology, natural environment, the economy, and life safety. For this reason, this study observes the flow behavior of particle collapse using experiments. This study mainly explores the collapse of the particle bed with different slope gradients and water flow through experiments and discusses the erosion and deposition phenomena. In the experiment, an open two-dimensional inclined flume was built, the inclined angle in the flume was adjusted manually, and the flow discharge of the incoming water was controlled by PLC, so that the water flow entered the inclined granular bed area. The particles used in the experiment are 4mm white alumina beads, which are photographed by a high-speed camera and then processed by image processing to analyze the flow phenomenon of the particles in the flow tank and use PIV to analyze the velocity field distribution of the fluid flow to observe the solidliquid two-phase flow. The experimental results mainly analyze the erosive bed and the depositional bed, respectively, after the particles are affected by the water flow, the erosion area size, erosion depth, and erosion distance in the eroded bed change with time, and the particles in the sedimentary bed are entrained by the water flow. The deposition area of the particles moved to the depositional bed changes with time, and the relationship between the deposition depth at different trough positions. Through the final erosion area, the distribution situation and erosion rate under the influence of different inclination angles and flow rates are analyzed, the relationship between the dimensionless final erosion area and potential energy loss is also iii described, and the distribution relationship is fitted with an exponential function. It can be known from the experimental results that when the water flow rate and the inclination angle are larger, the erodible particle bed and deposition will be significantly changed. When the water flow rate is larger, the erosion area and the deposition area are both positively correlated distributions. This is because the change of water flow will affect the original frictional resistance between the particles, which will destroy the original structure of the particles, which will lead to serious erosion and entrainment effects, and then affect the deposition area distribution in the sedimentary bed. From the erosion distance and the distribution of erosion depth at different positions in the trough, it is found that when the water flow and inclination increase, the effect of erosion will become more and more obvious. From the change of erosion rate and potential energy loss in the particle bed, it is found that the energy loss will be more severe when the inclination angle is larger.
顯示於類別:	[機械工程研究所] 博碩士論文

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