應用質點影像測速儀於垂直管內之長氣泡流場型態觀測

Flow Patterns of a Long Gas Bubble Penetration in a Vertical Tube by Using PIV

王得安(Te-An Wang)

指導教授 ： 許政行

中原大學/工學院/機械工程研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200935

摘要

摘要
　　本研究利用質點影像測速儀 (Particle Image Velocimetry) 搭配質量控制器 (Mass Flow Controller)，觀測長氣泡於垂直圓管中穿透不同黏度的牛頓流體所產生之流場型態與各項無因次參數變化，實驗藉由十種不同黏度的矽油與三種不同氣體注入量之差異進行觀測比較。
　　本研究首先利用高速單眼相機擷取長氣泡輪廓，利用圓管直徑與氣泡寬度計算出中空率，再利用質點影像測速儀所得之流場速度計算出雷諾數，毛細係數，迴流區域寬度與氣泡直徑比等無因次參數，並利用速度向量圖搭配無因次參數與實驗變數進行比較。
　　實驗結果顯示，氣泡的中空率在垂直圓管中會隨著毛細係數的增加，而逐漸趨近於0.61之定值，在三種氣體注入量不變之條件下，隨著流體黏度的增加，流場型態均逐漸由低黏度流體造成的迴流型態轉變為高黏度流體所造成的完全過度流型態，於迴流流場中，迴流區域所佔的寬度範圍會隨著氣體注入量或與流體黏度的增加而減少，且迴流區域寬度與氣泡直徑的比值會隨著中空率的降低而逐漸減少，並且呈現非線性之變化。

關鍵字

牛頓流體 ； 垂直圓管 ； 長氣泡 ； 質點影像測速儀

並列摘要

Abstract
　　In this research, the Particle Image velocimetry (PIV) incorporated with a Mass Flow Controller (MFC) are utilized to observe the variations of flow filed of a Newtonian fluid and associated non-dimensional parameters, which generated by a long bubble penetration into the fluid with different fluid viscosity, within a vertical circular tube. For the sake of comparison, ten silicon oils with different viscosity and three different injection volumes are used in the present study.
At first, a high speed camera is used to capture the shape of long bubble in the circular tube. Secondly, by using the diameter of circular tube and the deduced diameter of bubble, the hollow ratio is calculated. Then, apply the flow field velocity acquired by the PIV to calculate the non-dimensional parameters: Reynolds number, Capillary number, the ratio of the diameter of recirculation and the diameter of bubble, and finally the vector velocity images incorporate with the non-dimensional parameters are used to conduct the comparison。
The results show that values of the hollow ratio of the long bubble approach to 0.61 with the increase of Capillary number in the vertical circle tube, and under the conditions of three different gas injection volumes, with the increase of the fluid viscosity, the flow fields will transformed from bypass flow to Recirculation flow. In addition, the width of the recirculation zone decreases while either the gas injection volume or the fluid viscosity increases. Consequently, the ratio of the width of recirculation zone to the diameter of bubble decreases with the decrease of the hollow ratio, and the variations of the ratio is nonlinear.

並列關鍵字

Long bubble ； PIV ； Vertical tube ； Newtonian fluid

參考文獻

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17. 張清泉“流體特性對圓管內長氣泡發展影響之研究”,私立中原大學機械工程系,博士論文,2010,pp.27-65

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