臺灣博碩士論文加值系統

本論文研究孔隙檔板對於密度界面之穿透性捲增的影響, 研究內容包括理論分析與實驗工作, 實驗工作在壓克力模型內進行鹽浴實驗, 在穩態時, 有兩層不同密度的流體。實驗分為兩個系列,Exp.(100%) 與Exp.(62%) 系列,Exp.(100%) 系列沒有任何孔隙檔板在模型內部, Exp.(62%) 系列
在清水噴嘴出口約距1 cm 處擺置一個孔隙率為62%的檔板, 兩個系列根據清水源頭流量, 各別有三組實驗, 分別為10, 15和25 cm3s−1, 鹽水源頭在所有實驗中的流量固定為2.5 cm3s−1, 鹽水密度的範圍為1.09410 ∼1.09484 g cm−3。 實驗結果顯示, 密度界面的高度與清水源頭的動量有關, 本實驗工作使 用固定出口截面積的噴嘴, 隨著清水源頭流量增大, 清水源頭的動量增大, 密度界面到源頭的距離增加。與Exp.(100%) 系列相比, 在相同的清水源頭流量時,Exp.(62%) 系列減少密度界面到源頭的距離。 研究結果顯示, 上層流體的密度只與清水源頭流量和鹽水的浮力通量有關, 在固定的鹽水浮力通量條件時, 清水的源頭流量增加, 上層流體的密度隨之減小。然而兩層流體之間的密度差距與密度界面的捲增流量有關, 密度界面的高度和孔隙檔板扮演重要的角色, 與Exp.(100%) 系列兩層流體之間的密度差距相比, 在相同的清水源頭流量時,Exp.(62%) 系列有較高的密度差距。

The purpose of this research is to study the penetrative entrainment at the density interface by a flow passing through a porous baffle. The salt-bath technique is employed to conduct the experiments in an acrylic tank. In the steady state, there are two layers in the tank and each layer of them has individual density. Experiments are categorized into two series, Exp.(100%) and Exp.(62%). The Exp.(62%) series has a porous baffle, which is located about 1 cm away from the fresh water source nozzle, but the Exp.(100%) series does not have any baffle. Each series includes experiments with three different fresh water source flow rates, i.e. 15, 20 and 25 cm3s−1. The source of salt solution with a fixed flow rate, 2.5 cm3s−1, and the range of the density, from 1.09410 to 1.09484 g cm−3, give similar buoyancy fluxes in all experiments. Experimental results show that the distance between the fresh water source nozzle and the density interface increases with the fresh water source flow rate in the same series of experiments with the same source nozzle. Compared with the Exp.(100%) series, the Exp.(62%) series has a reduction distance between the source nozzle and the interface for the same fresh water source flow rate. The density of the upper dilute layer is determined by the buoyancy flux of the salt solution source and the flow rate
in the tank. As the flow rate increase, the density of the upper dilute layer decrease. In addition to the distance between the source nozzle and the interface, the porous baffle plays a role in the density step between two layers, which is determined by the penetrative entrainment flow rate at the interface. For the experiments with the same fresh water source flow rate, the Exp.(62%) series has a higher density step. Experimental results give the range of the penetrative entrainment rate from 0.77 to 1.12 when the range of the local Richardson number is from 0.47 to 4.05.

1.緒論
2.理論分析模型
3.實驗設置與方法
4.實驗結果與討論
5.結論與建議

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