本研究為垂直圓管上升氣水雙相流流譜量測與鑑別，利用壓力信號、差壓信號以及電導度信號所做量測信號的特性分析，並同時設有觀測段可供照相、攝影作為對比使用。由於目前尚無一套完整偵測信號的方法，故我們建立大量的數據庫，並對各種流譜做特性分析，希望能夠得到統一且客觀的雙相流流譜鑑別方法。本實驗提供了各流譜的大量實驗照片和影片，以及對各流譜的空泡分率進行討論，其中將特別針對束狀環狀流做更詳細的流譜特性分析。
束狀環狀流 (Wispy annular flow)為Bennett首先觀察到之流譜，此流譜會在氣核裡形成不規則之束狀結構 (Wisp)，其特性具有相當獨特之物理意義。從實驗結果顯示，當束狀結構出現時，壓力信號上會出現瞬間極大的壓力變化，而從壓力信號圖中我們可以看到會有一脈衝出現，此乃為判別束狀環狀流相當重要的方法之一。而分析上我們同時利用信號處理的方法來分別計算壓力信號和電導度信號的相關函數，因此可得到束狀結構之速度、出現頻率、出現時間長度、平均壓力和標準差以及平均壓力佔整體壓力之比例等實驗結果。
以上束狀結構之分析結果基本上其計算值都會隨著液相表面速度 (superficial liquid velocity)的增加而上升，當液相表面速度增加到達一定條件之後，其特性會有相當明顯地變化。然而對於氣相表面速度(superficial gas velocity)而言，似乎影響並不顯著。
本研究針對束狀環狀流做一相當深入的探討，不僅在判別環狀流和束狀環狀流的部份與前人之研究相互印證，其特性分析對於未來在鑑別流譜上亦扮演著非常重要的角色。

The proposed research is about analyzing and identifying different types of upward air-water two-phase flow regimes in the vertical pipe by measuring its pressure signal, differential pressure signal, and electric impedance signal. In addition, our research provides an observation section which is available for photographing and recording for data comparison. Currently, there is lack of a complete method for observing the signal; therefore, we create large database for analyzing the characteristic of each flow regimes. We want to have a unified and objective method to identify two-phase flow regimes in the future. This experiment provides photos, videos, pressure signal analysis, and void fraction analysis for each flow regimes. Especially, we provide a detailed analysis on wispy annular flow.
Wispy annular flow was first observed by A.W Bennett. This regime will form irregular wisp structure within the gas core and this characteristic has unique physical significance. The experimental result shows that when wisp is formed, the pressure signal will have an instantaneous pulse. The instantaneous pulse is an important indication for wispy annular flow. We use signal processing methods for calculating correlation functions for pressure signal and conductivity signal. Therefore, we can get experimental results for the velocity, frequency of appearance, time duration of appearance, average pressure, pressure standard deviation, and the ratio of average pressure and total pressure of wisp.
The experimental results of wisp given above would rise with the increase of superficial liquid velocity and change apparently when it reaches to a certain condition. However, the experimental results reveal that the characteristic of wisp is less dependent of superficial gas velocity.
In this study, we set up an experiment device which was carried out to investigate the flow characteristics of wispy annular flow. The large database we build is important for the flow regime identification and characteristic analysis about wispy annular two-phase flow.

1. Levy, S., Two-phase flow in complex systems. 1999: John Wiley & Sons.
2. Ghajar, A.J., Non-boiling heat transfer in gas-liquid flow in pipes: a tutorial. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2005. 27(1): p. 46-73.
3. Ishii, M. and M. Grolmes, Inception criteria for droplet entrainment in two‐phase concurrent film flow. AIChE Journal, 1975. 21(2): p. 308-318.
4. Bennett, B., et al. Paper 5: Flow Visualization Studies of Boiling at High Pressure. in Proceedings of the Institution of Mechanical Engineers, Conference Proceedings. 1965. SAGE Publications.
5. Wallis, G.B., Critical two-phase flow. International Journal of Multiphase Flow, 1980. 6(1): p. 97-112.
6. Hewitt, G.F., Churn and wispy annular flow regimes in vertical gas–liquid flows. Energy & Fuels, 2012. 26(7): p. 4067-4077.
7. Baker, O. Design of pipelines for the simultaneous flow of oil and gas. in Fall Meeting of the Petroleum Branch of AIME. 1953. Society of Petroleum Engineers.
8. Taitel, Y. and A. Dukler, A model for predicting flow regime transitions in horizontal and near horizontal gas‐liquid flow. AIChE Journal, 1976. 22(1): p. 47-55.
9. Weisman, J., et al., Effects of fluid properties and pipe diameter on two-phase flow patterns in horizontal lines. International Journal of Multiphase Flow, 1979. 5(6): p. 437-462.
10. Spedding, P. and V.T. Nguyen, Regime maps for air water two phase flow. Chemical Engineering Science, 1980. 35(4): p. 779-793.
11. Hewitt, G.F. and D. Roberts, STUDIES OF TWO-PHASE FLOW PATTERNS BY SIMULTANEOUS X-RAY AND FLASH PHOTOGRAPHY. 1969, Atomic Energy Research Establishment, Harwell (England).
12. Govier, G.W. and K. Aziz, The flow of complex mixtures in pipes. 2008: Society of Petroleum Engineers.
13. Taitel, Y., D. Bornea, and A. Dukler, Modelling flow pattern transitions for steady upward gas‐liquid flow in vertical tubes. AIChE Journal, 1980. 26(3): p. 345-354.
14. Hewitt, G. and P. Lovegrove, Experimental methods in two-phase flow studies. NASA STI/Recon Technical Report N, 1976. 76: p. 30510.
15. Brockett, G. and R. Johnson, Single-phase and two-phase flow measurement techniques for reactor safety studies. 1976, Intermountain Technologies, Inc., Idaho Falls, Idaho (USA).
16. Rouhani, S. and M. Sohal, Two-phase flow patterns: A review of research results. Progress in Nuclear Energy, 1983. 11(3): p. 219-259.
17. 簡國祥, 雙相流之空泡分率與質量流率量測. 1996.
18. 王郁文, 垂直管中雙相流譜鑑別與模式建立之研究. 1989.
19. Cooper, K., G.F. Hewitt, and B. Pinchin, Photography of two-phase flow. 1963: UK Atomic Energy Authority Research Group.
20. Vince, M., Flow regime identification and void fraction measurement techniques in two-phase flow. 1980.
21. Bergles, A., J. Roos, and J. Bourne, INVESTIGATION OF BOILING FLOW REGIMES AND CRITICAL HEAT FLUX. Final Summary Report. Report No. 797. 1968, Dynatech Corp., Cambridge, Mass.
22. Xu, X.-X., Study on oil–water two-phase flow in horizontal pipelines. Journal of Petroleum Science and Engineering, 2007. 59(1): p. 43-58.
23. Monrós-Andreu, G., et al. Water temperature effect on upward air-water flow in a vertical pipe: Local measurements database using four-sensor conductivity probes and LDA. in EPJ Web of Conferences. 2013. EDP Sciences.
24. Piper, T., Dynamic gamma attenuation density measurements. Unknown, 1974. 1.
25. Lassahn, G.D., LOFT three-beam densitometer data interpretation. 1977, Idaho National Engineering Lab., Idaho Falls (USA).
26. Prassions, P., Experimental data report for LOFT power ascension test L2-3. NUREG/CR-0792, TREE-1326, 1979.
27. Jones, O.C. and N. Zuber, The interrelation between void fraction fluctuations and flow patterns in two-phase flow. International Journal of Multiphase Flow, 1975. 2(3): p. 273-306.
28. Kelessidis, V. and A. Dukler, Modeling flow pattern transitions for upward gas-liquid flow in vertical concentric and eccentric annuli. International Journal of Multiphase Flow, 1989. 15(2): p. 173-191.
29. Vince, M. and R. Lahey, On the development of an objective flow regime indicator. International Journal of Multiphase Flow, 1982. 8(2): p. 93-124.
30. Hubbard, M. and A. Dukler, The characterization of flow regimes for horizontal two-phase flow. Heat Trans. & Fluid Mech. Inst., M. A. Saad and JA Miller, eds., Stanford U. Press, 1966: p. 101-121.
31. Kaichiro, M. and M. Ishii, Flow regime transition criteria for upward two-phase flow in vertical tubes. International Journal of Heat and Mass Transfer, 1984. 27(5): p. 723-737.
32. Griffith, P. and G.A. Snyder, The bubbly-slug transition in a high velocity two phase flow. 1964, Cambridge, Mass.: MIT Division of Sponsored Research,[1964].
33. Harmathy, T.Z., Velocity of large drops and bubbles in media of infinite or restricted extent. AIChE Journal, 1960. 6(2): p. 281-288.
34. Hinze, J., Fundamentals of the hydrodynamic mechanism of splitting in dispersion processes. AIChE Journal, 1955. 1(3): p. 289-295.
35. Sevik, M. and S. Park, The splitting of drops and bubbles by turbulent fluid flow. Journal of Fluids Engineering, 1973. 95(1): p. 53-60.
36. Brodkey, R.S., The phenomena of fluid motions. 1995: Courier Corporation.
37. AKAGAWA, K. and T. SAKAGUCHI, Fluctuation of Void Ratio in Two-Phase Flow: 2nd Report, Analysis of Flow Configuration Considering the Existence of Small Bubbles in Liquid Slugs. Bulletin of JSME, 1966. 9(33): p. 104-110.
38. Feldman, S., On the hydrodynamic stability of two viscous incompressible fluids in parallel uniform shearing motion. Journal of Fluid Mechanics, 1957. 2(04): p. 343-370.
39. Nicklin, D. and J. Davidson. The onset of instability in two-phase slug flow. in Proceedings of the Symposium on Two-phase Fluid Flow, Institution of Mechanical Engineers, London, Paper. 1962.
40. Lamarre, E. and W.K. Melville, Instrumentation for the measurement of void-fraction in breaking waves: laboratory and field results. Oceanic Engineering, IEEE Journal of, 1992. 17(2): p. 204-215.