| 摘要: | 為能增加對海洋放流表層稀釋特性之瞭解,本文以垂直圓管浮昇射流模擬汙染物於承受水體表層流場內之稀釋混攪現象,並應用雷射誘發螢光原理所發展而成之一維陣列濃度量測系統對此流場進行定量之實驗研究,由實驗結果除歸納出純射流及浮昇射流之中軸稀釋率、表面稀釋率及表層流場之經驗估算式,同時亦發現無論純射流或浮昇射流,其中軸稀釋率於表層流場以外區域均隨無因次距離呈線性成長,然於浮昇效應漸控制流場之特性變化時,其線性趨勢則不同於純射流之結果。至於表層流場以內之中軸稀釋率則皆呈均勻分布,當浮昇射流之水體在到達自由水面之前,若僅經歷純射流特性區及漸變區,則其表面稀釋率之增加趨勢較經歷浮昇流特性區為小,由此可知,浮昇效應具有提昇稀釋率之效益,此外,此效應亦使表層流場有增加之現象。
To improve the understanding of dilution processes of ocean outfall in the surface-impinging region, a array detection system based on laser-induced fluorescence was employed to investigate the concentration field of a vertical round buoyant jet. From the experimental results, the empirical formula of axial and surface dilution was obtained for the pure momentum jet and buoyant jet. In the fully developed region of pure or buoyant jets, the axial dilution will increase linearly with dimensionless longitudinal distance except that, when the buoyant effects dominating the flow field, the tendency of dilution increase would be different. As the jet fluid entering the impinging region, the concentration field shows a characteristic of uniform distribution for both of pure and buoyant jets. From the comparison of buoyant jet dilution, it shows that the buoyant effect play a positive role in improving the surface dilution. |
