Numerical simulation for heat transfer and velocity field characteristics of two-phase flow systems in axially rotating horizontal cans

摘要

Volume of fluid (VOF) element method coupled with a finite volume (FV) discretization technique was used to simulate two-dimensional, transient, two-phase flow patterns (air-water and air-food material) in an axially rotating horizontal can for rotational speeds of 10-160 rpm. Rotational Reynolds number ranged from 1700 to 27200 and 0.88 to 14.1 for water and food phases, respectively. FV solution was per-formed on a moving mesh system representing the can motion in on-axis axial rotation with respect to an inertial-fixed frame. Since the two-phase flow pattern prediction was an important aspect of modeling fluid mixing and improved heat transfer in canning process, reliable time- and spatially-dependent flow pattern maps were given to identify the rotational effects on two-phase flow characteristics and to deter-mine flow patterns prevailing at different rotational speeds. Single-phase and food-phase flow computa-tions with the corresponding flow patterns were also provided for a direct comparison with air-water results to further determine the physical limitations of the rotational effects. Numerical results demon-strated that two-phase flow patterns were significantly influenced by increasing rotational speeds lead-ing to distinguishable flow patterns in terms of air-liquid (water/food material) interface characteristics and associated headspace air bubble movement through the liquid phase.