Identification of flow parameters in thin-film apparatus using a multi-channel image analysis system.

• The characteristics of original multi-channel image analysis measuring system for liquid film thickness changes with annular two-phase gas-very viscous liquid downward flow in vertical pipes has been presented. • The methodology of conducting study with the tests and analysis results of selected air-oil two-phase flow values has been presented. • The apparatus system introduced in the paper, is believed to be the most effective in terms of investigating the characteristics of oil liquid films and other dielectric liquids with a significant level of absorbing monochromatic radiation. • The measuring system introduced in the paper is believed to be very useful for industry. This paper presents the capabilities of an optoelectronic system to measure values describing the hydrodynamics of a two-phase downward flow in vertical pipes of a highly viscous liquid and gas. Common image processing methods used in the literature are unsuitable for the analysis of two-phase flow with particularly complex flow patterns. The designed and constructed measuring system and the appropriate selection of working media allowed measurements of a number of quantities characteristic for the gas–liquid flow falling in vertical pipes. The methodology of conducting measurements and their results as well as the analyses of selected quantities characterizing the two-phase flow are presented. The nature and form of the occurring waves are characterized. Experimental data are more accurate than those obtained with methods described in the literature. A camera placed in the flow channel limits the measurement to vertical downward flow only. [ABSTRACT FROM AUTHOR]