Vertical annular flow pattern characterisation using proper orthogonal decomposition of Electrical Impedance Tomography

Annular flow is one of the most important multiphase flow regimes primarily because of its presence in extensive industrial applications,such as steam generators, evaporators, condensers and boiling water reactors. There is a great need to have specific techniques capable of extracting characteristics of annular flow pattern via experiment and/or modelling, which is essential to understand specific annular flow phenomena. The intention of developing a mathematical decomposition method for flow regime recognition comes from the fact that each regime is characterised by unique dynamic behaviour. The direct approach with Proper Orthogonal Decomposition (POD) was previously introduced by Lumley, which required a very large amount of relevant data from experimental multiphase and process conditions is necessary. The presented approach is to apply POD on a large amount of tomograms for identification of annular flow pattern in a gas-liquid two phase flow, which also provides a new method to extend the current evaluation procedure of Electrical Impedance Tomography (EIT) for imaging of air-water pipeline flows.The paper demonstrates the capability of the proposed method with a study on annular flow patterns in vertical pipeline.