Effect of the ‘end of the vortex’ phenomenon on the particle motion and separation in a swirl tube separator

The gas and particle flow patterns in computational models of swirl tube gas separators were simulated and compared with experiment, focussing on the presence and the effects of the end-of-the-vortex (EoV) phenomenon. It was found that for some swirl tube body lengths there are two possible stable positions of the vortex core depending on the inlet flowrate: a) centralized and following the swirl tube axis and b) bending to the swirl tube wall, which constitutes the EoV phenomenon, at a stable axial position. The computational results showed a good agreement with previous experimental observations of the EoV and they confirmed some specific features, which are typical for the EoV behaviour. Lagrangian simulations of the flow of particles in the swirl tube made it possible to visualize the particle motion and understand how the EoV phenomenon affects the behaviour of a single particle during separator operation and through this how the presence of an EoV affects separation efficiency of swirl tubes in general.

The 'end of the vortex' is the phenomenon when under some conditions the vortex core deviates from the axis of the cyclone separator and attaches to the wall, where it rotates at some level above the bottom of the separator. Simulated particles behaviour is very similar to the experimental observations.Figure optionsDownload as PowerPoint slideHighlights
► Two positions of the vortex core were found: centralized and remained on a wall.
► Simulations confirmed the flow behaviour, observed experimentally.
► The effect of the EoV on particle trajectories was obtained.
► Lagrangian simulations described how the EoV affects the efficiency of separation.