| 摘要: | 由於人類經常需要進行儲物的動作，因此儲槽於各種產業及民生當中都是非常重要的存在，尤其是用於儲存顆粒物料，而儲槽開口的大小、內部顆粒粒徑與內部流場均會對排放造成影響。在達到一定條件下，架橋一旦形成就會使整體排放永久堵塞，這對於產業及民生使用上都是一大困擾。
本研究主要是使用類二維儲槽系統，於開口上一定高度內擺放一轉動置入物，並且向左進行橫向位移，再搭配控制器設定轉速，於實驗時填入固定重量的顆粒進行排放，而為了擷取實驗顆粒排放的過程，使用了高速攝影機進行影像擷取，以及粒子追蹤程式PTV(Particle Tracking Velocimetry)來分析影像，再透過探討質量流率、速度、堆積分率及粒子溫度，來了解轉動置入物的加入對於整體流動的影響及比較。
經過一系列的實驗後了解到，擺放轉動置入物後確實會影響整體顆粒排放，並且當置入物在不同位置下所得到的趨勢也有所差異，當置入物在過低高度時，轉動行為對於排放影響最為直接，且置中狀態下形成的架橋非一般型態架橋，而是直接與置入物連接的架橋，因此轉動的影響最為顯著，置入物偏移擺放後開口上方與置入物間出現更多空間，在一定的水平位移距離內能使流率顯著提升；置入物在適當高度時，轉動仍能提供顆粒產生足夠的水平速度，使顆粒間發生碰撞降低架橋產生，置入物水平位移後仍能夠使顆粒排放有不同的趨勢產生，在轉速增加的同時，也能看出其對於流率的影響，在實驗後統計出最佳的置入物擺放位置，並了解其流動行為，最後得出在本實驗配置下，當置入物在18毫米高、向左偏移5毫米有最佳流率。;People often need to store things, so silo is very important in various industries and people′s livelihood. Especially for storing granular materials. The size of the outlet of the silo, the size of the internal particle size and the internal flow field all affect discharge. Under certain conditions, once the clogging is formed. The overall discharge will be permanently stopped, which is a big problem for industry and people′s livelihood.
This research builds a two-dimensional silo, then places a rotating obstacle within a certain height above the outlet, and makes a lateral variation to the left, and then the rotation speed is set with the controller. Fill in the particles with a fixed weight for each experiment. In order to capture the process of experimental particle discharge, a high-speed camera is used for image capture, and use PTV (Particle Tracking Velocimetry) to analyze the image. Then discuss the flow rate, velocity, packing fraction and granular temperature to understand the impact and comparison of adding rotating obstacle to overall discharge.
After experiments, it is found that placing a rotating obstacle will affect the overall particle discharge, and the trends obtained when the obstacle is at different positions are also different. At too low position, the obstacle has the most direct impact on the discharge. When the obstacle at centered state, the clogging formed is not a general type, it directly connected to the obstacle, so the impact of rotation is the most significant. After offsetting the obstacle, there is more space between the top of the outlet and the obstacle. Then the flow rate can be significantly improved within a certain horizontal displacement distance. When the obstacle is at an appropriate height, the rotation can provide horizontal velocity for the particles, so that the collision between the particles can reduce the clogging happened. The horizontal displacement of the obstacle can still make the particle discharge have different trends. Finally, through experimental statistics, determine the best position of the obstacle and understand its flow behavior. |
