許銘熙2006-07-252018-06-292006-07-252018-06-2920002000-07-31http://ntur.lib.ntu.edu.tw//handle/246246/10684束縮段渠道常見於通水斷面突然縮小之水道，用以連接上下游水道，減少輸水之能量損失或使水流通暢。當河道上游為一超臨界流流況時，水流經束縮段渠道後，常會產生斜震波，造成下游水道水位不穗定等現象”若束縮段束縮比率過大將會造成頸塞流況之發生。 為研究渠道束縮段複雜之水理流況，首先將對直牆式束縮段矩形渠道之水理現象進行分析，研究內容除對渠道束縮段水理影響參數無因次分析外，在考慮不產生頸塞流況之現象下，提出一適合之束縮段長度之計算方式，以減少斜震波對渠道下游之影響。 此外，利用渠道二維數值模式進行渠道超臨界流之數值棋擬，並將棋挺結果與理論分析相互比較，研究成果將可做為束縮段超臨界流渠道水理分析之參考。The contraction channel connecting upstream and downstream channels is designed for reducing the energy lose of water flow. When the inflow condition is supercritical flow, the flow in channel contraction will generate oblique shock waves, and make the downstream flow unstable. However, the large channel contraction ratio will generate the choking flow. In this study, the theoretical analyses for the choking flow and suitable length of transition in straight-wall channels are investigated. The non-dimensional parameters affecting the water depth in rectangular contraction channel are deduced from the dimensional analysis. In addition, a two-dimensional numerical model was developed to simulate supercritical flow in channel contractions. A series of numerical experiments were carried out to analyze the effects of the non-dimensional parameters. As a result, the suitable lengths of the channel contraction are proposed to reduce the influence on the downstream flow field. The results of this study can be used for the hydraulic analysis and design of channel contractions in supercritical flow.application/pdf834386 bytesapplication/pdfzh-TW國立臺灣大學生物環境系統工程學系暨研究所渠道束縮段適合長度斜震波Channel ContractionsSuitable LengthOblique Shock Wavesreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/10684/1/892211E002049.pdf