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題名 | 浮昇射流之拉氏模式數值模擬=The Numerical Simulation of Buoyant Jets with Lagrangian Approach |
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作者 | 楊文昌; 黃榮鑑; | 書刊名 | 中國土木水利工程學刊 |
卷期 | 11:1 1999.03[民88.03] |
頁次 | 頁163-173 |
分類號 | 440.137 |
關鍵詞 | 浮昇射流; 拉氏模式; 軸向捲增; 強制捲增; Buoyant jet; Lagrangian model; Axial entrainment; Forced entrainment; |
語文 | 中文(Chinese) |
中文摘要 | 本文擬建立一個以時間為自變數的拉氏捲增積分模式, 來模擬浮昇射流的發展, 並作為流場預估的有效工具。數學模式的推導遵循流體力學的守恆定律,捲增機制分解成射 流剪力衍生的軸向捲增和環境流嵌入的強制捲增,強制捲增量將以幾何物理的關係來推導。 模式的驗證是以實驗數據來比較穩定環境流場中射流的軌跡和濃度,而驗證的流況包含動量 射流場、重密度射流場、射口角度不同的射流場與環境水域密度層變分佈的射流場等。驗證 結果顯示在固定的捲增係數下射流軌跡和濃度之發展曲線與實驗數據之比較,其吻合程度相 當良好。 |
英文摘要 | Based on the unique independent variable of time, a Lagrangian integral model is established in this paper to simulate the development of a buoyant jet. The mathematical formulation starts with the conservation laws of fluid mechanics. Entrainment mechanism is divided into the axial entrainment induced by the shear of jet flow and the forced entrainment generated by the impingement of ambient flow, with the latter derived from the geometric relations of the jet element. The model is verified by comparing the predicted trajectory and concentration, in cases of the momentum jet, dense jet, oblique jet and buoyant jet into the density-stratified flow, with those of the experimental data. For the cases with identical entrainment coefficients, the results obtained by both the prediction and experiment appear to be in good agreements. |
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