Impact of non-uniform surface roughness on the erosion rate and performance of a cyclone separator

Abstract

The present study investigates the influence of non-uniform surface roughness on the performance and erosion rate of a Staimand cyclone separator. Non–uniform roughness is considered for the cylindrical part, cone, and vortex finder of the cyclone. Three-dimensional simulations are performed using the Reynolds stress turbulence model (RSM). The Eulerian-Lagrangian approach is used for tracking solid particles. The results reveal that non-uniform surface roughness affects the flow pattern, collection efficiency, erosion rate, and pressure drop significantly. The maximum tangential velocity in the cyclones with the roughened surfaces is 1.3 times the inlet velocity. The maximum tangential velocity is reduced when the range of roughness height decreases. As the range of roughness height is enhanced, the axial velocity increases considerably. For instance, at the axial position of y = 0.75D, the value of axial velocity is about 0.34 and 0.08 times the inlet velocity for states 1 and 6 of the descending non-uniform roughness (DNUR) case, respectively. It is observed that the pressure drop in the cyclones with non-uniformly roughened surfaces is less than that in the cyclone with smooth walls. For the cut-off size diameter d100, four states of the ascending non-uniform roughness (ANUR) cyclone can completely collect the particles with diameters of 4.8, 4.9, 5, and 6 µm, while the smooth-walled cyclone can collect 7-µm particles with the collection efficiency of 100%. Besides, it is demonstrated that the erosion rate of cyclones with non-uniformly roughened walls is less than that of smooth-walled one for all mass loads.