儲槽內加入圓形轉動置入物對於顆粒排放行為之影響

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题名:	儲槽內加入圓形轉動置入物對於顆粒排放行為之影響
作者:	吳青鴻;Wu, Ching-Hung
贡献者:	機械工程學系
关键词:	儲槽;顆粒體;架橋;粒子流;置入物;轉動;Silo;Particle;Arch;Granular flow;Obstacle;Rotation
日期:	2021-07-19
上传时间:	2021-12-07 13:21:16 (UTC+8)
出版者:	國立中央大學
摘要:	在工業及生活中，儲槽經常扮演著儲存顆粒的角色，在需要時將顆粒排放，而儲槽的出口大小、顆粒的粗細、內部的流場都會影響排放情形。在符合一定條件下，架橋的產生使整體儲槽形成永久堵塞，這對一般業界或民生用途上有很大的困擾。本論文主要是建置類二維儲槽，在槽內加入一順時針旋轉置入物，透過電子控制器調整轉速及利用氣壓閥來開閉出口，填入固定重量的顆粒，且為了捕捉顆粒的照片以及未來分析上的用途，搭配高速攝影機及粒子追蹤程式PTV (Particle Tracking Velocimetry)來分析數據，探討質量流率、速度、堆積分率隨轉速的變化，及轉速對架橋產生能力和破壞能力的比較。從一系列的實驗後得到，加入轉動置入物確實會影響其排放物理量，並且在不同高度下所得到的趨勢有所不同，在高置入物位置下，置入物不易影響顆粒排放，當慢慢降低置入物的高度，因為高度下降導致顆粒水平速度變大，使碰撞程度及機會增加，導致排放因為碰撞的關係而變得有所不同，而當置入物到了過低高度，因為置入物是最接近開口的，對於排放的影響是最明顯，但在此位置所形成的架橋卻與其他高度有所不同。在增加轉速的過程中，也可以看出其對於架橋破壞或產生的趨勢，並可搭配剪率擬合出一線性關係並且進行預測。 ;In industry and life, storage tank usually plays an important part of storing or discharging the particles when we needed. Some factors will affect storage tank discharging situation, such as the outlet size of silo, particle’s thickness and the internal flow field. Under certain conditions, storage tank will appear arch to stop discharging which is an annoying issue for general industry or people’s livelihood. This research was built a two-dimensional silo adding a clockwise rotation obstacle into the silo, also using electronic controller to change obstacle speed and open the outlet by air compressor. Filling fixed weight particles and captured particle’s photographs to analyze data with high speed camera and PTV (Particle Tracking Velocimetry) code. The flow rate, velocity field, packing fraction with changing rotation speed and compared arching formation, destruction ability will be discussed in the end. After a series of experiments, it is found that rotating obstacle will affect the discharging physical quantities and the trends will be changed by different obstacle’s height. At higher positions, the obstacle is not easy to affect discharge but when obstacle height reduced, it will cause velocity change which make the degree of collision increase. Silo’s discharging situation will be different and changed by particle collision. When the obstacle reaches a too low position, the effect of discharging is most obvious because it is closest to the outlet than the other heights also the arch formed at this position is different. In the process of increasing the speed, it can be seen tendency of damage or produce the arch and can be matched with the shear rate to fit a linear relationship and make predictions in the future.
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