Numerical Modeling of the Twisted Flow of Evaporating Polydisperse Vapor-Droplet Mixture

The subject of the work is a numerical study of thermo-hydrodynamic processes in the flow of a methane vapor–droplet mixture in one of the elements of a device for heating mixtures of gases and liquids. The subject of the research is the study of the physical processes occurring in liquefied natural gas regasification apparatuses. The purpose of the work is to reveal the regularities of the dynamics of a polydisperse vapor–droplet mixture in a pipe with heated walls. The dynamics of the carrier medium is described by the system of Navier–Stokes equations for a compressible heat-conducting medium, taking into account the exchange of mass, momentum, and energy with the dispersed phase. The dispersed phase includes several fractions differing in size. Each fraction is described by a system of equations consisting of the continuity equation for the average density, the conservation equations for the momentum components, and the thermal energy conservation equation, taking into account the interaction of the multifraction dispersed phase with the carrier medium. The mathematical model takes into account the swirl of the flow by taking into account the tangential components of the velocity vectors of the carrier phase and fractions of the dispersed phase. The systems of equations of motion of the carrier medium and fractions of the dispersed phase are solved by the McCormack explicit finite-difference method of the second order. To overcome numerical oscillations, a scheme of nonlinear correction of the grid function is used. At each time step, the main part of the computational algorithm is supplemented by a droplet evaporation model with subsequent correction of the hydro- and thermodynamic parameters of the mixture. As a result of the calculations, a significant difference is revealed in the intensity of evaporation of the fractions of the liquid methane phase of the mixture, which have different sizes of dispersed inclusions; it is also determined that during the movement of the evaporating mixture, the highest pressure of the vapor phase is observed near the inflow of the methane mixture into the pipe with heated walls. The revealed regularities can be applied in devices working with gas–liquid media.