Taking CFB as background of application

a study on strongly swirling turbulence of gas-solid two-phase flow in a separator with a square cross-section has been carried out by using a three-dimensional laser-based particles dynamic analyser （3D-PAD）. The results show:（1） the distribution of swirling flow field in the said square-shaped separator has a forced swirl in the centre

but a quasi-free swirl near the side wall

and a partial swirl existing in the place of edge-angle. Particles’ mutual collision in the place of edge-angle makes the quasi-laminar flow pulsation there to be strengthened

the dynamic energy of the turbulence and the strength of partial turbulence near the edge-angle to obtain a comparatively large value

consuming large amount of energy

being of benefit to particles’ separation at the edge-angle; （2） Above the separator

the max value of average falling velocity along the vertical direction is near to the right side of the flow-guiding cone （while the inlet is at the leftside）. In the medium and lower-part of the separator

the max falling velocity is situated at the right wall surface of the separator. The direction of velocity in the central part of the cross-section is upward

and recirculation occurs here.