CFD analyses of liquid flow characteristics in a rotor-stator reactor

Abstract

Rotor-stator reactor (RSR) is a novel device for the intensification of multiphase processes and can greatly boost mass transfer and mixing efficiency. However, due to the unique structure, the flow characteristics in the RSR is unknown and difficult to acquire by experiments. Therefore, this work employed computational fluid dynamics (CFD) technique to reveal liquid flow behaviors in an RSR for the first time. The volume of fluid (VOF) multiphase model, sliding model (SM) and standard k–ε model were used to simulate liquid flow field in a typical two-dimensional computational framework of the RSR. It was found that the droplet size and velocity in the cavity zone of the RSR were in agreement with the published data of the visual experiments. The results show that the liquid was quickly split and synchronized with the motion of the rotor layers when injected into the RSR. Two droplet formation schemes were observed in the RSR: “ligament to droplets disintegration” and “droplets disintegration”. The droplets size distribution could be well described by Rosin–Rammler model. The droplets diameter decreased but the droplet velocity increased with increasing rotational speed, while the droplets diameter increased and the droplet velocity changed little with increasing liquid inlet velocity. With the increase of the number of rotor/stator layers, droplet size decreased and velocity increased. The agreement of the experiment and simulation results indicate that the CFD technique is an effective tool to analyze the hydrodynamic characteristics of RSR.