本論文的研究目的為探討入口擋板孔隙率對排空房間的影響, 研究工作
以縮尺壓克力模型進行鹽浴實驗, 模型內部入口處放置一個具有孔隙率的
擋板, 根據擋板孔隙率, 實驗組別分為EM(79%) 及EM(60%) 兩系列
的排空實驗, 又依據模型上下開口的面積比,R=1, 0.5和0.33, 分為三個小
組實驗。理論分析模型以流場型態是否因為上開口福祿數而改變, 分成兩個
理論模型, 分別為單一(single-stage) 及兩段式(two-stage) 的流場型態,
依照與實驗結果的比較, 本論文選擇單一流場型態的理論模型。實驗結果顯
示, 當孔隙率較大時, 排空的過程可分為排空密度層和排空混合層兩階段,
孔隙率較小時, 則僅有排空密度層的過程。隨著孔隙率的增加, 排空密度層
的時間會減少, 而完全排空的時間會增加。當整體有效開口面積或縮減重力
增加時, 排空密度層的時間和完全排空的時間均有減少的趨勢。當擋板孔隙
率或整體開口有效面積增加時, 混合層初始交界面高度會增加。混合層的初
始浮力與兩個參數, 密度層捲增至混合層的流量以及密度層的排空時間, 有
關, 隨著整體開口有效面積的增加, 混合層的初始浮力有增加的趨勢; 雖然
密度層捲增至混合層的流量隨之增加, 但是密度層的排空時間則是隨之減
少。

This research studies the Emptying-box problem with the porous
baffler behind the entrance opening. The salt-bath technique is employed to conduct the experiments by using the acrylic reduced-scale model.
According to the baffler porosity percentage, the experiments
are categorized as two series, EM(79%) and EM(60%). Each series includes three different opening area ratios, R=1, 0.5 and 0.33.
There are two theoretical models in terms of the propensity of mixing at the interface: single-stage flow type and two-stage flow type.
Comparing experimental results and theoretical models, I choose the
single-stage flow type as the theoretical model in this research. Ex-
perimental results show that emptying processes for the larger baffler
porosity cases consist of emptying the dense layer and emptying the
mixed layer, but there is only one process of emptying the dense
layer for the smaller baffler porosity cases. As the baffler porosity
increases, the emptying time for the dense layer decreases, but the
total emptying time for the whole box increases. The emptying times
for the dense layer and the whole box both decrease, when the total
effective opening area or the reduced gravity increases. The initial
interfacial height of the mixed layer increases, when the baffler
porosity or the total effective area increases. The initial buoyancy of the
mixed layer is related to the penetrative entrainment flow rate from
the dense layer to the mixed layer and the emptying time for the
dense layer. As the total effective opening area increases, the initial
buoyancy of the mixed layer tends to increase; and the penetrative
entrainment flow rate increases as well, but the emptying time for
the dense layer decreases.

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