The effect of the cyclone dust outlet shape on the flow field pattern and velocity profiles has been investigated computationally using Reynolds stress turbulence model (RSM) for four cyclone separators (without dustbin, with dustbin, with dipleg, and with dust hopper (dipleg plus dustbin)). Results show that, the maximum tangential velocity is almost the same for the four tested cyclones. No acceleration occurs in the cyclone space (the maximum tangential velocity is nearly constant throughout the cyclone). Neglecting including the dustbin in the flow domain causes a slightly over estimation of the pressure drop. While a negligible under-estimation in the pressure drop is obtained when neglecting the effect of
dipleg. The axial velocity profiles for the four cyclones are different. An inverted V profiles when including the dustbin and an inverted W profiles without the dustbin or with the dipleg. The differences between the pressure drop and cut-off diameters obtained with and without the dustbin or dipleg are minor. Consequently, the numerical simulations of cyclone separator without dustbin or dipleg are quite acceptable with large saving in computational resources.