Two-Phase Internal Flow: Toward a Theory of Everything

Abstract

Two-phase flow and heat transfer is still an area of intense research and great uncertainty. Even severely restricting ourselves to just annular, internal two-phase flow does not significantly improve our chances of accurately predicting either pressure gradients or heat transfer coefficients for an arbitrary tube geometry or fluid. This article summarizes a series of investigations that aim to identify the fundamental governing physics of internal two-phase flow: a Theory of Everything. The techniques developed to do so have been varied, and novel approaches are presented here. At the macro scale, simultaneous visualization and measurement of pressure gradient have led to interesting observations about the relationship between flow regimes and these fundamental macroscale behaviors. Since the macroscale behaviors are governed, for the most part, by behaviors at the micro scale, a number of techniques have been developed to study this near-wall behavior in quantitative detail. In particular, dye-assisted planar laser induced fluorescence has provided the first accurate portrayals of the gas-liquid interface annular flow, and microscale multiphase particle image velocimetry has been used to obtain the velocity within the liquid film of annular flow from within micrometers of the wall to velocities within the waves 500 µm or more from the wall. Statistical analyses of these data point toward a general approach for modeling wall shear in two-phase concurrent internal flow.

Reprint of: A multiphase, micro-scale PIV measurement technique for liquid film velocity measurements in annular two-phase flow

“…It is hypothesized that this is due to the intermittency of the relatively high velocity waves: the shear beneath the waves may be high, but they are present for only 20-25% of the time (Schubring et al, 2010), so do not significantly impact the mean shear measured in the viscous region. A statistical analysis by Shedd (2012) suggests, but does not yet prove, that the waves isolated from the base film may be well-predicted by von Kármán's Law of the Wall.…”

Reconstructing the Phase Distribution Within an Annular Channel by Electrical Resistance Tomography

“…Deep understanding on two-phase flow mechanics is vital in process design and safety assurance in industry, and also in academics where the two-phase flow model and heat and mass transfer are of primary interest [1]. Annular flow channels are seen in adiabatic processes such as cooling systems, and their flow regime is of interest to the investigation on the heat transfer efficiency in cooling system design and safety [2]. These kinds of flows are also seen in coating systems and Couette devices.…”

Research on the Conductivity-Based Detection Principles of Bubbles in Two-Phase Flows and the Design of a Bubble Sensor for CBM Wells

“…Theoretical research on two-phase flow bubbles of coalbed methane based on laboratory simulation tests is the focus of current research. The existing data show that the theoretical forecasting research results of different scholars differ greatly, have significant errors, and are inconsistent with actual production [ 5 , 6 , 7 ]. Therefore, a more direct, reliable, and accurate method, namely the real-time detection of bubble parameters during the operation of CBM wells, can be adopted.…”