矩形管中流體經鄰近壁面之圓柱狀質源之混合對流研究

A Study of Duct Flow Passing in A Channel with Cylinder Sources adjacent to Planar Boundary

林冠宏(Kuan-Hung Lin)

指導教授 ： 王 立 文

元智大學/工程學院/機械工程學系/碩士(2003年)

摘要

本實驗研究是將鄰近壁面之圓柱狀質源的質量傳遞引入矩形管道主流中，在不同的傾斜角度、強制對流效應與改變銅板質源位置以及銅板與圓柱間的陰陽極性變化來進行質混合對流研究。在此，混合對流係指利用幫浦所造成的強制對流（forced convection），在速度完全發展之後，再與不連續之對稱質源傳遞所形成的自然對流（natural convection）合併之流體運動現象。
實驗使用的工作流體為硫酸銅水溶液（CuSO4 + H2SO4 + H2O），藉由電化學系統於測試區（test section）之銅板與水道中鄰近壁面之銅柱加上端電壓，使其成為電極，達成濃度梯度之建立。
本實驗採用雷射光暗影法（shadowgraph）作流場結構觀察及照相記錄，並作質量傳遞率的量測。實驗的無因次參數範圍如下：Ar=1 ，Sc=1700~2400，Re=50~300，Gr,m=9.45×105，θ=-15°~15°，d / H = 0.25 ( 圓柱直徑與管道高度比 ) ，h/d = 0 ,3(銅柱表面距銅板最小高度與圓柱直徑比)。
至於質傳遞率量測方面，固定傾斜角時，在不同邊界條件下，質傳遞率Sherwood數隨Reynolds數的增加而增加，Case(B)的Sherwood值遠比其他Case小但可藉由增加傾斜角度的方式改善質傳遞率；而當圓柱有正質通量，平板有負質通量時，圓柱越接近平板，其質傳效果愈佳。

關鍵字

圓柱狀質源 ； 混合對流 ； 電化學系統

並列摘要

An experimental investigation of mixed convection mass transfer from a cylinder and a plate mass sources flow of a CuSO4＋H2SO4＋H2O solution will be carried in an inclined rectangular channel with an electrochemical system .
The purpose of the present study is to investigate laminar fully developed flow in inclined rectangular channels with the types of the boundary of test section are: (A) cylinder is cathode and top plate is anode (B) cylinder is anode and top plate is cathode (C) cylinder is cathode and bottom plate is anode (D) cylinder is anode and bottom plate is cathode. The influence of the mass transfer rate and the boundary types between the sources has been investigated. The experiments would include three parts : (1)inclined angle θ= 0°(2)inclined angle θ> 0° (3)inclined angle θ< 0°.
To visualize the flow, the shadowgraph technique will be used. Electrical measurements will be used to obtain mass transfer rates and to infer a Sherwood number. The ranges of the parameters in the work are Ar=1, Sc=1700~2400, Re=50~300, Gr,m = 9.45×105 ,θ= -15°~ 15°,d / H = 0.25,h / d=0,3.
The mass transfer rate, Sherwood number, increases with increasing Re for a fixed inclined angle. When the cylinder is anode, Sherwood number increases with increasing inclined angel, but quaking decreases with decreasing inclined angel.

並列關鍵字

cylinder sources ； mixed convection ； Electrical measurements

參考文獻

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