Abstract:
This paper describes the application of the erratic concept in the identification of two-phase gas-liquid flow patterns and transitions in a large vertical riser. The analyzed data in this paper were from the experimental conducted in the 4-inch diameter pipe. In the experiments, vertical gas-liquid two-phase flow was studied in a large cross-sectional area. The complete analyses covered the range experimentally attainable .
Usually, the flow pattern identification, and gas void fraction of two-phase flows are based on visual observation of phase distribution. While visual flow pattern identification may be sufficient for a number of instances, for many circumstances these methods are inappropriate or too biased. The objective of this study is to apply probability density function (PDF) and local distribution of averaged void fraction concepts, on experimental data of dynamic signals of gas-liquid two-phase flows, in an effort to identify and interpret the creation and transitions of flow pattern in downward flow. These methods will possibly give a favorable way in the identification of flow behavior. The plots of probability density function (PDF) confirm that, a bubbly to intermittent flow transition was occurring at all positions. The flow regime observed at the bottom region of pipe was accompanied by a wide base spanning from 0 to 0.6. The existence of large bubbles in a liquid phase contributes to the wide base of void fraction values. Annular flow was a dominant type in a downward flow, particularly when gas superficial velocity increased to higher rates. The achieved results were in good agreement when compared with data of local gas void fraction distribution, obtained from wire mesh sensor (WMS) technique.
