How particles with sizes close to cut size affect the multiphase flows and performance of hydrocyclones

Hydrocyclones classify particles by size but face inefficiency in handling particles with sizes close to the cut size (referred to as cut-size-near particles). This paper presents a numerical study on the cut-size-near particle behavior and its impacts on cyclone performance using a validated two-fluid model. The particle size distribution of interest follows a Johnson's SB distribution, with a median size of d0.5 and a spread of σj. The case of d0.5 close to a reference cut size is focused, where values of σj accord with various fractions of cut-size-near particles. The numerical results show that a larger σj decreases the water split and separation precision while increasing the cut size and pressure drop. Generally, the effect of σj exerting on a larger hydrocyclone is more apparent, even causing a plateau in partition curves. These phenomena are elucidated by the detailed analysis of multiphase flows and forces acting on particles.