Evolution of views on the wave structure of a liquid film in annular dispersed gas-liquid flow

The wave structure of a liquid film blown by a high-velocity gas flow with entrainment of droplets from the film surface has been investigated. The paper presents an analysis of existing methods of measuring the thickness of the local fluid film and a review of the classical concepts of wave hydrodynamics of annular dispersed flow obtained in early studies using crude methods. A systematic description of the structure, evolution, and interaction of waves of various types is made based on analysis of high-resolution spatio-temporal records of film thickness obtained by laser-induced fluorescence. The results are compared with the results of modern experiments, and the necessity of revising some classical concepts is shown. Directions for further research are suggested.