半環狀封閉區域中熱質之自然對流現象

Natural Convection Heat and Mass Transfer in a Semiannular Enclosure

王立文(LW. Wang) ； 賴順達(S.D. Lai) ； 李慶中(C.C. Lee)

《中國航空太空學會學刊》 28卷1期 (1996/03) Pp. 19-25

https://doi.org/10.6124/TAASRC.199603_28(1).03

摘要

本文實驗在研究一半環狀封閉區域中熱質對流現象。此一半環狀封閉盒之內、外壁保持一固定但不同的溫度，半環狀封閉盒內之流體爲CuSO4+H2SO4+H2O之水溶液，質量的傳遞由電化學方法來達成。本文的主要目的是藉由實驗方法來探討半環狀封閉區域中，由溫度梯度及濃度梯度所引起的自然對流之流場型態和濃度分佈。流場型態觀察係使用雷射光暗影法(shadowgraph)來達成，由流場之照片可以顯示出在順向或逆向流場中，封閉盒內有多層渦流的流場結構，此外，逆向流場中則有Finger type flow的產生。
流場的濃度分佈是以非干擾性的方法測得。此法是利用光線透過硫酸銅容液時，被銅離子所吸收的光強度和溶液的濃度成正比的關係，而可求出該點的平均濃度；另對於不同流場型態的質傳遞率亦分別量測。本實驗的無因次參數研究範圍如后：Ar=0.21, K=2.5, Sc=1700~2300, Pr=6.5~7.3, Gr, t=10^4~l0^6, N=-15~+10。

關鍵字

熱質 ； 自然對流

並列摘要

An Experimental investigation of heat and mass transfer was carried out for a semiannular enclosure. Inner and outer walls of the enclosure are kept at different but constant temperatures. The semiannular enclosure is filled with a CuSO4+H2SO4+H2O solution. An electrochemical method has been used for the mass transfer. The purpose of this study is to investigate flows resulting from buoyancy forces due to a combination of both temperature and concentration gradients in an enclosure. The flow structure in an enclosure is visualized by the shadow-graph technique. Flow visualization photographs show interesting multicell flow structures in an enclosure for both aiding and opposing thermal and solutal buoyant forces. In the opposing cases the flow patterns show finger type flow. Concentration distributions at different times are quantitatively measured. An optical technique is based on the idea that the intensity of light beam absorbed by the copper sulphate solution is proportional to the solution concentration when the light beam pass through the solution. For each flow regime the mass transfer coefficient across the enclosure is also measured.

並列關鍵字

heat and mass transfer ； natural convection