Application of high-speed laser-induced fluorescence technique for studying annular gas-liquid flows

Wavy structure of liquid film in annular gas-liquid flow was studied using high-speed modification of LIF technique. Two-wave structure, consisting of primary waves, generating secondary waves on their back slopes, was shown to exist in regimes with and without entrainment. Three-dimensional structure of waves was also investigated. Existence of transverse instability of primary waves at high liquid Reynolds numbers was shown. It was also shown that such instability enhances generation of fast and slow secondary waves.