Modeling and analysis of swirling flow in cyclone separators using various hybrid scale-resolving approaches

This work investigates both experimentally and numerically the turbulent flow within cyclonic separators using DES and VLES turbulence methods. Numerical predictions are validated against Hoekstra’s experimental data, showing that DES accurately captures the tangential velocity and pressure drop, but struggles to reproduce the axial velocity, particularly near the vortex core. Several outlet boundary conditions, including the addition of an obstacle, are tested to improve flow representation. A mapped pressure boundary condition offers a more physically consistent solution. Furthermore, spectral analysis is used to identify the end of the unsteady transient regime and the dominant flow frequencies. The effect of cyclone body height is also investigated both experimentally and numerically by comparing two industrial configurations. Shorter cyclone bodies lead to lower velocities and higher swirl numbers at the cyclone body and near the outlet, while taller cyclones significantly mitigate the Precessing Vortex Core effect and reduce vortex intensity at the outlet region.