Two-phase flow and pressure drop in a horizontal, equal-sided combining tee junction
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Date
2016
Authors
Joyce, Gavin D. A.
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Abstract
A careful review of the literature showed that there is a serious lack of information
(experimental or analytical) on the pressure losses during two-phase flow in combining
tee junctions. Pipe networks in industrial applications involve combining and dividing
junctions and knowledge of the pressure losses at these junctions is essential for
analysis of the flow distribution in the network. To this end, the pressure losses
of air-water mixtures passing through a horizontal, combining tee junction with a
37.8 mm diameter were experimentally studied with annular, wavy, and slug flow
regimes in the outlet. The test matrix independently varied the outlet flow rates,
the outlet mixture qualities, the gas distribution between the inlets, and the liquid
distribution between the inlets. All experiments were conducted at room temperature
and a nominal absolute pressure at the centre of the junction of 150 kPa. The pressure
distribution in all three legs of the tee was determined using up to 49 pressure taps
distributed among the three sides and monitored using pressure transducers to produce
accurate measurements of the pressure losses. Time-averaged pressure measurements
with annular and wavy flows are reported, while pressure measurements with slug flows
were not repeatable. A new model and empirical coefficients is presented that allows
accurate prediction of pressure losses for flows with either an annular or wavy outlet.
Time-varying pressure measurements are presented and analyzed using probability
density functions. Different distributions were found for differential measurements
depending on whether or not slugging was present in the system. The probability
density functions for cases with annular or wavy flow in the outlet followed Gaussian
distributions, while cases with slug flow had skewed distributions. Time-varying
pressure signals showed a time lag between slug events based on pressure tap locations.
A visual study with slug flow present in the system showed upstream travelling waves
induced in a stratified inlet when slug flow was present in the other, which led to
unexpected slugging under certain flow conditions.
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Keywords
Two-phase flow, Combining tee, Pressure drop, Experimental, New correlations