Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/15151
標題: 單階自由跌水之速度場量測與分析
On the Velocity Field of Free Overfall
作者: 黃文彥
Yen, Huang.Wen
關鍵字: Overfall;跌水;Sliding jet;Pool;滑動舌流區;水墊區
出版社: 土木工程學系
摘要: 
本文旨在利用精密量測儀器光纖雷射杜普勒測速儀及運用顆粒追蹤之流場可視化法,針對自由跌水下之滑動舌流區及水墊區(迴流區),於來流條件為亞臨界流至超臨界流間 ( Fr = 0.75 ~ 1.32 ),所進行之速度場量測之研究。在本實驗中滑動舌流區內之速度分布係為類似半射流(half-jet)曲線,其最大速度發生在極接近水表面的位置上,並發現在不同來流條件下,在水舌與水墊交接的撞擊區附近速度剖面具有相似性,最後利用速度場中之ur、vr計算分析流場中的方均根速度、雷諾剪應力以及總剪應力的分布曲線。此外,在水墊區域中亦做同樣精密的量測,並嘗試由平均水平速度剖面進行無因次分析,發現當在水墊區通氣完全時,水墊區內固定範圍內可得到相當良好之相似剖面,用來確實了解水墊區流場的結構,以作為未來探討多階消能工的基礎。

The characteristics of the velocity field of a free overfall (including the velocity profiles of and near the sliding jet, and in the pool) are investigated experimentally, using a novel flow visualization technique as well as fiber laser Doppler velocimetry (FLDV). The range of Froude number for the approaching flow upstream of a drop structure is from 0.75 to 1.32. The mixing between the jet and the pool was found to be intensive and the velocity profiles look like those in half jet. Using these jet-like velocity profiles, it was possible to calculate the viscous shear stress, Reynolds stress and total shear stress in the sliding jet. Several detailed flow structures, regarding the mean horizontal velocity distributions and the circulating vortex flow inside the pool of a drop structure, are elucidated in the present study. An unique similarity profile of the mean horizontal velocity measured inside the pool is proposed both for supercritical and subcritical approaching flow conditions.
URI: http://hdl.handle.net/11455/15151
Appears in Collections:土木工程學系所

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