Abstract
The purpose of this study is try to clarify and simulate the two-phase flow inside a Tee-junction. More than one hundred sets of test data were recorded and analyzed to establish a complete data base for model banchmarking. At the same time, a theoretical model was developed to simulate the complex phenomena of the two-phase flow inside the Tee-junction.The experiments of this study were not only providing the low pressure test data to complete the gas-liquid two-phase flow teat data of Tee-junction, but also providing the void fraction data to modified the drift-flux model of horizontal pipe.A physically-based theoretical model was developed in this study to simulate the gas-liquid and steam-water two-phase flow in a horizontal tee-junction. The basic mass, momentum, and energy conservation equations are usedin establishment of this model. The model includes five independent equations, they are the mixture continuity equation, the vapor phase continuityequation, the X-direction momentum equation, the Y-direction momentum equation and the energy equation. Any five unknown hydraulic parameters of the Tee-junction can be solved in various ways, for virtually any choice of three well-posed boundary conditions. The uncertainty of the interfacial terms and empirical constants were compared with the experimental data gathered from the literatures. The comparison shows that the predictive ability of the present model is reasonably well, not only for gas-liquid two-phase flow but also for steam-water two-phase flow, as the interfacial evaporization and condensation terms were introduced into the model to modify thecalculating results.雙相流通過 T型歧管所造成之分流, 相分離及壓力分佈之變化是一般工業上時常碰到之流體現象. 在核能工業上 T型歧管在核子反應器相關管路之設計應用上時常出現,特別是在輕水式反應器 (LWR)之冷卻水流失事故(LOCA)現象研究及分析時, T型歧管分流及壓降計算之準確性更形重要. 雖然國內以往在此方面之資訊及量測技術均很缺乏, 但本研究為瞭解 T型歧管中雙相流各種複雜現象並能將其予以準確模擬計算, 故排除各種困難, 不僅完成 133組底壓氣一水雙相流之水平 T型歧管實驗, 同時發展一理論分析模式.本研究之實驗補足以往氣一水雙相流實驗中在極低壓力部份之空白, 使模式校驗之範圍更廣泛. 同時提供空泡分率, 壓力分佈等重要實驗數據, 不僅可作為建立空泡分率之漂移通量關係式修正之用, 同時可據以作為判斷文獻中參數不全之數據之準確性的重要依據.本研究之理論分析模式使用二維流體力學中基本之質量守恆方程式, 動量守恆方程式及能量守恆方程式作為理論分析基礎, 可用來計算水平 T型管路中次音速 (Subsonic) 雙相混合流之分流, 相分離及壓力降之現象. 校驗結果顯示本模式能正確預測水平 T型管路中氣一水雙相流之相分離與壓力降, 且適合廣大之實驗操作範圍, 無論對氣一水雙相流或蒸汽一水雙相流, 理論之預測均能符合實驗結果.研究中並自行設計一台高頻訊號處理器, 使由阻抗法量測空泡分率準確且可行. 同時此空泡分率量測法已提供作為流譜鑑別之用, 而且可提供作為單一氣泡或彈狀流氣泡流速之量測儀器.