Experimental investigation of the Kelvin–Helmholtz instabilities of cylindrical gas columns in viscous fluids. (August 2018)

• Record Type: Journal Article
• Authors: Zhao, Huayong; Bhabra, Benjamin
• Is Part Of: International journal of multiphase flow. Volume 105(2018)
• Page Start: 74
• Page End: 83
• Publication Date: 2018-08
• Subjects: Kelvin–Helmholtz instabilities -- Viscosity -- Cylindrical interface; Multiphase flow -- Periodicals; Écoulement polyphasique -- Périodiques; Multiphase flow; Periodicals; 620.1064
• DOI: 10.1016/j.ijmultiphaseflow.2018.03.017
• Languages: English
• ISSNs: 0301-9322

Abstract

Highlights: The Kelvin-Helmholtz instability conditions for a cylindrical interface between two viscous fluids are solved analytically. The most unstable conditions predicted VCVPF-KH model match well with most measured air column breakup conditions. The critical instability conditions are sensitive to the interface and chamber size but not the most unstable conditions. The critical instability conditions are sensitive to the perturbation symmetry but not the most unstable conditions. Abstract: This paper derives analytical solutions for the critical Kelvin–Helmholtz (KH) instability conditions at the interface between a cylindrical gas column and a pool of viscous immiscible fluid confined in a chamber of finite size. The analysis focuses on conditions of negligible heat and mass transfer. The derivations are based on the established approaches reported in the literature with different boundary conditions. The most unstable instability conditions have also been calculated numerically. Experiments designed to measure the actual air column break-up conditions in water have been carried out to validate the analytical models. Comparisons show that the most unstable conditions predicted by the Viscous Corrections of the Viscous Potential Flow KH model are the best match to the experimentally measured break-up conditions. Parametric investigation of the instability theories shows that the vapour column size has a noticeable effect on the critical conditions, but has a negligible effect on the most unstable conditions when the column radius is greater than 1.2 mm. Furthermore, the critical instability conditions are sensitive to the chamber size and the perturbation symmetry, while the most unstable conditions are insensitive to these parameters.