An investigation on hydrodynamic behavior of horizontal gas–liquid intermittent flow by S-PLIF and parallel-wire conductance sensors

•A S-PLIF system is designed to detect the interface structures of horizontal gas–liquid intermittent flow.•The effects of the interface fluctuations and detached bubbles on the S-PLIF70&90 results are investigated.•Hydrodynamic parameters are detected by paired parallel-wire conductance sensors and compared with previous correlations.•The interface structures and hydrodynamic parameters are uncovered as the flow condition changes. Horizontal gas–liquid two-phase flows widely exist in a variety of industrial fields such as the environment, chemical industry and energy. Intermittent flow, characterized by the quasi-periodic alternation motion of liquid slugs and large-scale Taylor bubbles, is the most prevalent flow pattern in horizontal gas–liquid two-phase flows. Comprehensive research on the hydrodynamic behavior of gas–liquid intermittent flow is essential for revealing the mass and heat transfer characteristics between phases, thereby establishing physical models of flow parameters. In this study, a structured planar laser-induced fluorescence (S-PLIF) system and paired parallel-wire conductance sensors (PWCSs) are designed to detect the gas–liquid interface structures and the hydrodynamic parameters. The S-PLIF system consists of a laser, a visualization box, a Ronchi ruling-plate and a pair of high-speed cameras. An optical linear prism forms a laser sheet in the transverse direction and the middle of the test section, and the cameras are positioned at 70° and 90° respectively to the plane of the laser sheet, referred to as S-PLIF70 and S-PLIF90. Under the laser excitation, bright and dark stripes generated by the Ronchi ruling-plate are deflected at the gas–liquid interface. The influence of total reflection can be effectively avoided by identifying the deflection position of the stripes, allowing for accurate detection of the gas–liquid interfacial structures. The effects of the interface fluctuations and detached bubbles on the S-PLIF70&90 results are investigated. Fluctuation and evolution characteristics of the gas–liquid interface are analyzed by probability density function (PDF) and power spectral density (PSD). Meanwhile, hydrodynamic parameters, i.e., Taylor bubble nose and tail velocity, Taylor bubble and slug length, and slug frequency, are detected by the PWCSs, and compared with previous correlations. The evolution characteristics of the interfacial structures and hydrodynamic parameters are uncovered as the flow condition changes.