水-空氣兩相流於水平平滑圓管內的流譜與壓降分析

Abstract

本研究以實驗方法觀察水-空氣在管徑3 mm、 5mm及7mm，長度皆為100 mm石英圓管內之流譜變化，與探討水-空氣在測試段銅管長度各為1000 mm在水平狀態之絕熱壓降特性。實驗系統測試條件是在一大氣壓與20℃的環境下操作，測試範圍其表面氣體速度從0.01 ~100 m/s，表面液體速度從0.001~5 m/s；質量流率(Mass Flow Rate)從50~700 kg/m s；測試段入口氣體乾度從0.0001至1。 實驗結果顯示，由於表面張力的影響，觀測流譜與Baker (1954)、Weisman (1979)、Mandhane (1974)、Taitel & Dulker (1976)流譜圖比較，發現並不適用。Damianides & Westwater (1988)及Barnea et al. (1983)在3 mm管徑的實驗結果與本實驗結果相當吻合。3、5 mm的管徑在質量流率G = 50 kg/m s並無環狀流的存在，間歇流則佔了實驗流譜圖很大的區域範圍。 Klimenko & Fyodorov (1990)的關係式對本實驗結果也有很好的預測性。從分離流(波浪分離流)流譜圖，可看出質量流率的不同與兩相摩擦倍數有相當密切的關係；對於環狀流(Annular)流譜圖，其質量流率與兩相摩擦倍數無關，本論文亦建立兩相摩擦倍數與質量流率的關係式。

Abstract Two-phase flow pattern and friction characteristics for air water system in a 3.17 mm smooth tube are reported in this study. The range of mass flux is between 50 to 700 kg/m2×s. The experimental data show that the two-phase friction multipliers are strongly related to the flow pattern. For stratified-wavy flow pattern, a mass-flux dependence of the two-phase multipliers is seen. For annular flow pattern, the two-phase frictional multipliers are independent of mass flux. Correlations are developed to describe the frictional multipliers. Meanwhile, depending on the mass flux, the mechanism of flow pattern transition to the annular flow pattern is different. Two-phase flow pattern and friction characteristics for air-water mixtures inside a 3.17 mm smooth tube are reported in this study. The range of mass flux is between 50 to 700 kg/m2×s. Conclusions of the present study include: (1) Depending on the mass flux, the mechanism of flow pattern transition to the annular flow pattern is different. (2) The two-phase multipliers are strongly related to the flow pattern, and it is found that the two-phase multiplier is dependent upon mass velocities for the partially-wet stratified-wavy flow pattern. For intermittent and annular flow pattern, the two-phase multipliers are insensitive to the change of mass flux. (3) The simple criterion proposed by Klimenko and Fyodorov (1990) shows an good classification of the stratified and un-stratified data. It is suggested that the crieterion of F = 3 be used to distinguish the annular flow pattern. (4) Correlations of frictional multipliers were developed for separate flow regime. Namely annular flow and non-annular flow pattern. To employ the appropriate correlation, one should use the Klimenko and Fyodorov (1990) criterion with F = 3 to identify the locus of the flow regime.