Experimental Study of Two-Phase Air–Water Flow in Large-Diameter Vertical Pipes

Abstract

Recently, due to an increase in production demand in nuclear and oil and gas industries, the requirement to migrate toward larger pipe sizes for future developments has become essential. However, it is interesting to note that almost all the research on two-phase gas-liquid flow in vertical pipe upflow is based on small-diameter pipes (D 100 mm), and the experimental work on the two-phase gas-liquid flow in large-diameter (D > 100 mm) vertical pipes is scarce. Under the above circumstances, the application of modeling tools=correlations based on small-diameter pipes in predicting flow behavior (flow pattern, void fraction, and pressure gradient) poses severe challenges in terms of accuracy. The results presented in this article are motivated by the need to introduce the research work done to the industries where the data pertaining to large-diameter vertical pipes are scarce and there is a lack of understanding of two-phase gas-liquid flow behavior in large-diameter (D > 100 mm) vertical pipes.The unique aspect of the results presented here is that the experimental data have been generated for a 254-mm inner diameter vertical pipe that forms an excellent basis for the assessment of modeling tools=correlations. This article (i) presents the results of a systematic investigation of the flow patterns in large-diameter vertical pipes and identifies the transition between subsequent flow patterns, (ii) compares it directly with the existing large-(150 mm) and small-diameter data (28 mm and 32 mm) in the same airwater superficial velocity range, (iii) exemplifies that the existing available empirical correlations=models=codes are significantly in error when applied to large-diameter vertical pipes for predictions, and last (iv) assesses the predictive capability of a well-known commercial multiphase flow simulator.

The experimental study of counter-current two-phase flows in annuli

“…Inferring void fraction data from differential pressures is a low cost, simple and robust method used in experimental studies. Often this method is used to calibrate more advanced measurement techniques such as wire mesh sensor and electrical resistivity tomography (Farman Ali & Yeung, 2015). It is assumed that frictional and acceleration components of the total pressure gradient are negligible compared with the hydrostatic term, an example tested mathematically by for counter-current bubble and slug flow regimes in an annulus.…”

“…Despite the maturity of studies on co-current gas-liquid flow behaviours in vertical pipes Farman Ali & Yeung, 2015; and in vertical annuli (Caetano et al, 1992;, few studies are available on experimental investigation of counter-current flows in vertical pipes . Table 3-1 summarises studies of flow regimes observed in counter-current two-phase flow experiments conducted in vertical pipes.…”