臺灣博碩士論文加值系統

本研究探討紊流噴泉在密度界面之穿透性捲增流量的穩態實驗量測。研究工作以壓克力模型進行鹽浴實驗,實驗初始條件為上下兩分層的流體,上層為清水,下層為鹽水,清水源與鹽水源分別置於壓克力模型不同的高度位置,清水源置於壓克力模型頂部,清水源噴嘴出口有一層不鏽鋼網目,使流出的清水流體為紊流,鹽水源置於壓克力模型底部上方2 cm 的位置,藉由壓克力圓管供應鹽水至下層。研究使用光源衰減技術對拍攝的實驗影像進行分析。根據不同的鹽水密度與清水體積流量,本研究共有八組實驗。實驗結果顯示,實驗在穩態的情況下,密度界面高度與清水的體積流量和鹽水的密度有關;相同鹽水密度的實驗顯示,隨著清水流量增加,清水源與密度界面之間的距離增加;相同清水流量的實驗顯示,當鹽水密度增加,清水源與密度界面之間的距離減小。穩態的理論模型提供三個方程式估算本研究實驗裝置的穿透性捲增流量。本研究使用紊流噴泉模型估算在密度界面的紊流噴泉半徑、垂直速度與體積流量,然後以這些結果計算穿透性捲增率、理察遜數與密度福祿數,本研究結果顯示,在密度界面的理察遜數範圍在0.030至4.261之間,穿透性捲增率的範圍在0.13至2.32之間。

This research uses an experimental arrangement to measure the penetrative entrainment flow rate due to a turbulent fountain at a density interface in the steady state. The salt-bath technique is employed to conduct the experiments in an acrylic model. Experiments start with two layers of fluids initially, i.e. fresh water as the top and salt water as the bottom. Two sources, a fresh water source and a salt water source, are located at different heights in the acrylic model. A fresh water source is placed at the top of the acrylic model, and there is a stainless steel mesh placed at the outlet of the fresh water nozzle to make the outflow become turbulent. A salt water source is placed at 2 cm above the bottom of the acrylic model by using an acrylic pipe to supply salt water to the bottom layer. Dye attenuation technique is used to analyze the light intensity data derived from the recorded images of experiments. According to the density of salt water and the volume flow rate of fresh water, there are eight experiments in this research. The experimental results show that the interface height is highly related to the density of salt water and the volume flow rate of fresh water in the steady state. For the experiments having the same density of salt water, the distance between the density interface and the fresh water source increases with the increasing volume flow rate of fresh water. For the experiments having the same flow rate of fresh water, when the density of salt water increases, the distance between the density interface and the fresh water sources decreases. The theoretical model gives three equations to estimate the penetrative entrainment flow rate in the steady state. The theoretical turbulent fountain model gives the turbulent fountain radius, the vertical velocity and the volume flow rate at the density interface to estimate the penetrative entrainment rate, the Richardson number, and the densimetric Froude number. The research results show the Richardson number at the density interface between 0.030 and 4.261, and the penetrative entrainment rate in the range of 0.13 to 2.32.
Keywords: Density interface, turbulent fountain, penetrative entrainment, steady-state experimental arrangement.

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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