Flow maps in multiphase flows

Abstract

Flow structure maps are the most useful tool in the process of identifying structures formed in multiphase flows. They can be defined as a graphical way to present the transition boundaries of flow structures, depending on the characteristic pa-rameters of the phase transformation or flow, such as the vapor quality, the void fraction, the mass flow density, or the velocities of individual phases. Maps are usually two-dimensional drawings, described with a minimum of two selected parameters or quantities describing the phenomenon. The oldest maps of flow structures concerned adiabatic flows, mainly two-phase water-air systems or three-phase water-oil-air systems in conventional channels. Maps of nonadiabatic flow structures are simple and allow the selection of an appropriate model to determine the heat transfer coefficient as well as the flow resistance of the refrigerant. This has a major impact on the design of flow devices, where two- and even three-phase flows. This paper includes reviews of proposed maps of multiphase flow structures by various authors.