Estudo numérico do escoamento bifásico (líquido-gás) em uma célula de balanço usando software ANSYS Fluent

Abstract

Multiphase flows in pipes can cause various problems such as pipe wear. In order to obtain more understanding about biphasic flow, one can simulate the flow through experimental or computational means. However, flows in industries, such as oil, have large proportions, making it impossible to reproduce them in a laboratory environment. The use of balance cells in computational experiments and simulations can be an alternative to reduce flow geometry. In this paper, the dynamics of a two-phase liquid-gas flow in a rock-flow cell is studied, using two-dimensional and transient numerical simulations. For the flow modeling, the Volume of Fluids Model is used, together with the k-ε Turbulence Model. In the numerical modeling, the finite element-based finite volume method, interfacial tension, pressure-velocity coupling algorithm (SIMPLE) and the piecewise linear interface calculation (PLIC) will be used through the ANSYS FLUENT software. Numerical simulations were performed to analyze the flow rates, velocities and phase distributions in the balance cell for different liquid holdups (30, 40 e 90% of the cell volume) for the same rotation (0,925 rad/s) at maximum angle of 17.5º. The results obtained by the simulations were validated with experimental results obtained from NUEM-UTFPR (Multiphase Flow Center). Through the numerical results it was possible to analyze profiles and gradients of velocity, turbulent viscosity and shear stress on the walls for each phase and at the interface. As a consequence, it has been found that the shear stress at the interface cannot be approximated to the wall stress for the gas phase, as assumed in mechanistic models for biphasic flow.