Wave characteristics during cocurrent gas–liquid pipe flow Original Research Article

A new non-intrusive video imaging analysis technique (VIMAT) is presented for the accurate measurement of wave velocity and wave length during co-current gas–liquid flow in horizontal and slightly inclined pipes (−2° < β < 2°). Wave velocity and wave length measurements with VIMAT are performed with the systems air/water and air/water–glycerol with superficial gas velocities up to 16 m s−1, including the solitary-waves/atomization regime. It was found that the wave type (smooth, periodic 2D and 3D, solitary) depends on the superficial gas velocity while the wave velocity depends on the superficial liquid velocity. A model is introduced to calculate the interfacial wave velocity, which takes the wave type and liquid velocity profile into account. A good agreement is found between model and experimental values.