Measuring the Presence of Wetness in Vapour Flow Using Optical Imaging Technique

Two-phase flows consisting of vapour and liquid, are critical for the efficient operation of energy transfer and energy storage systems. This study demonstrates the use of the optical imaging technique of shadowgraphy, combined with a custom-developed image processing algorithm, to enable real-time, non-invasive assessment of the quality of two-phase flows. By mining data from high-speed imaging and applying pattern analysis and recognition techniques within ImageJ, vapour quality was accurately estimated at the onset of wetness in steam flow conditions. Measurements at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$50 ~\mathrm{m} / \mathrm{s}$</tex> flow velocity and 1.3 bar pressure revealed a vapour content of 0.983, validated against condensate trap and mass flow balanced data. The presented methodology advances optical measurement technique for two-phase flows, which offers potential in field-based process control requiring accurate fluid status characterisation.