A drag model for the gas-solid vortex unit

A drag model for the Gas-Solid Vortex Unit is presented. A large set of experimental data, obtained using static gauge pressure measurements, Particle Image Velocimetry and Digital Image Analysis in different GSVU geometries is used to estimate the model parameters with regression analysis. A large range of radial particle Reynolds numbers, particle densities and particle diameters is investigated. The newly proposed drag coefficient correlation, including 95% confidence intervals, reads:CD,GSVU=15.00±4.65ε2Rep,R−0.28±0.05S0.76±0.03 The drag coefficient correlation is found to depend on the swirl ratio S, a variable determined by the GSVU geometry. The model suggests that, for the operating conditions in the GSVU, the particles mostly behave independently of one another. The performance of the model to predict the pressure drop over fluidized beds in a centrifugal field is high as compared to the standard drag models for fluidized beds in the gravitational field. Additionally, the drag model eventually allows to calculate the azimuthal solids velocity in a GSVU under varying operating conditions using an Archimedes/Reynolds number correlation derived from the radial momentum balances for both phases. [Display omitted] •Drag models for gravitational fluidized beds not applicable in GSVU.•Experimentally validated GSVU drag coefficient correlation developed.•GSVU drag coefficient correlation depends on swirl ratio.•Ar/Re number correlation developed for GSVU.