Análise numérica do fenômeno Vortex Breakdown em escoamentos rotativos

Abstract

Numerical simulations in rotating flows similar to that in cyclones and combustion chambers were performed in this work, in order to verify and characterize the formation of vortex breakdown phenomenon. Cylindrical and conical-cylindrical geometries, both closed, were used in simulations. The rotating flow is induced by the bottom wall, which rotates at constant angular velocity, and the other walls are nonmoving with no-slip boundary conditions. First, the numerical results were compared to experimental results available in references, aiming to verify the capacity of the computational code to predict the vortex breakdown phenomenon. Afterwards several simulations varying the parameters which govern the characteristics of the flows analyzed in this work, i.e. the Reynolds number and the aspect ratio, were performed. In these simulations, the transitional limit and the limit of vortex breakdown formation were verified. Steady and transient cases, with and without turbulence modeling, specifically dynamic model, were simulated. In general, some aspects of the process of vortex breakdown in conical-cylindrical geometries was observed to be different from that in cylinders.