Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/14845
標題: 垂直式消能池之尾檻尺寸對振盪流場之頻率特性研究探討
Study on the characteristics of the frequency of oscillation flow in plunging pool by varying dimensions of sill
作者: 楊勝嘉
關鍵字: periodic oscillation flow;週期性振盪流
出版社: 土木工程學系
摘要: 
中 文 摘 要
本研究係運用鋁粉微粒追蹤之流場可視化法與光纖雷射杜普勒測速儀、水位計的定量量測,針對垂直式消能池中週期性振盪流場的特性作一研究探討。由於週期性振盪流場的運動形態十分複雜,為了能夠清楚的掌握其水理之現象及瞭解流場振盪的機制與渦流消散增長之情形,在確認實驗段及其上下游流場之均勻性與穩定性後,遂使用高解析度具連拍功能之相機搭配雷射切光、鋁粉微粒之流場可視化方式,從模型構造較簡單的單階跌水工、具有設置尾檻之垂直式消能池、至具有自由液面之空穴流場等不同尺寸之模型佈置,作一定性觀察之實驗研究。在觀察比對流場後,將流場作區別分類為週期性振盪流、非週期性振盪流─舌流、滑流,以確定產生週期性振盪流場的型態特徵,以利更進一步之定量量測研究。
繼而改變尾檻長度與高度(Ls、h)、消能池之模型長度與跌水壁高度(L、H)、不同來流之臨界水深與臨界流速(Yc、Uc)等實驗條件,針對在尾檻高度對跌水壁高度比(h/H)為0.128 ~ 0.71或跌水壁高度與尾檻之高度差對跌水壁高度比(Δh/H)為0.29 ~ 0.872會產生週期性振盪流之範圍下,使用光纖雷射杜普勒測速儀及水位計進行量測─流速(u)、水位(η)變化,經頻譜分析後得到週期性振盪流之第一調和頻率(f0),進而研究探討週期性振盪流場之發生範圍。
最後利用Buckingham氏之π定理與統計迴歸之方式,對量測所得數據資料作因次分析與迴歸分析探討。透過以上方法分析,所得之相似性為 ~ 之關係(尾檻長度對消能池長度之比(Ls/L)為零或無窮大的情形下)及 ~ 之關係─適用於有限尾檻長度(Ls/L不可為零或無窮大)之條件。其所得之相似性可全面地考量到週期性振盪流各個參數之特性及其影響,將不受到消能池各部位尺寸之差異與來流條件不同之影響。

ABSTRACT
The present study is to make clear the characteristics of periodic oscillation flows over two-dimensional vertical drop energy-dissipators, using flow visualization technique, fiber laser Doppler velocimter (FLDV) and the wave gauge. Flow visualization technique of aluminum particle tracking method was used for qualitative observation and recognizing the phenomenon of periodic oscillation flow from the appearance of non-periodic oscillation flows, i.e., napped flow and skimming flow. Both fiber laser Doppler velocimeter and wave gauge were used for quantitative measurements. Spectrum analysis was used for calculating the fundamental frequency of oscillation flow.
As regard the case of the periodic oscillation flow, the important variables, which substantially affect the primary oscillation frequency of the periodic oscillation flow, include the critical velocity (Uc) and critical water depth (Yc) of the approaching flow, the gravity acceleration (g) of the free overfall, and the dimensions (L, H, h, Ls) and height difference (Δh) of the vertical drop energy-dissipator.
According to Buckingham π- theorem and the regression analysis, it is surprisingly found that two similar relationships between and and between and can be achieved. These two similar relationships are independent of the dimensions of the vertical drop energy-dissipator and conditions of the approaching flow.
URI: http://hdl.handle.net/11455/14845
Appears in Collections:土木工程學系所

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