Abstract The present study aims at investigating numerically the effect of changing height ratios of cylinder and cone on the cyclone performance. Ratios of the cylindrical and conical segments are changed in a way that the total cyclone height remains the same. Eight different models with increasing barrel height viz. H/D = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 (wherein H/D = 4.0 corresponds to the cyclone model without a conical segment) are evaluated. All the cyclones operate at a Reynolds number (based on a body diameter of 0.205 m) of 2.71 · 105. The fluid domain is discretized with Cartesian mesh using Ansys workbench 16.2. The velocity and pressure fields, collection efficiency, and pressure drop in each model are predicted using large-eddy simulation (LES) with standard Smagorinsky model (Cs = 0.1) for sub-grid scales. Conclusive results indicate that increasing the length of the cylindrical segment significantly reduces the pressure drop with a marginal decrease in the collection efficiency. Furthermore, the cylinder-to-cone ratio affects the fluctuating field much more than the mean flow field. The frequency with which the vortex core precesses is also presented for each model.