Original Research Paper Numerical simulation of flow field in three types of standard cyclone separators H. Safikhani a,c, * , M.A. Akhavan-Behabadi a , M. Shams b , M.H. Rahimyan a a School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran b Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran c KIASA Co., 3848, Industrial Estate No. 1, Arak, Iran article info Article history: Received 24 November 2009 Received in revised form 25 December 2009 Accepted 7 January 2010 Keywords: CFD Gas–solid 1D3D cyclone 2D2D cyclone 1D2D cyclone abstract The numerical simulation of the fluid flow and particle dynamics is presented by CFD techniques to char- acterize the performance of the three types of standard cyclones. The three types of cyclones named 1D3D, 2D2D and 1D2D. The length of cylindrical part of the body is equal to 1, 2 and 1 times of the body diameter, respectively; and the length of the conical part is 3, 2 and 2 times of the body diameter. The Reynolds averaged Navier–Stokes equations with Reynolds stress turbulence model (RSM) are solved by use of the finite volume method based on the SIMPLE pressure correction algorithm in the computa- tional domain. The Eulerian–Lagrangian computational procedure is used to predict particles tracking in the cyclones. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). The depen- dency of cyclone characteristics on its diameter is investigated and D 50 (Cut-Point) is calculated for dif- ferent Particle Size Distributions (PSDs). The numerical results are compared with the experimental data and the theoretical model and good agreement is observed. Ó 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. 1. Introduction Cyclones are widely used in the air pollution control and gas– solid separation for aerosol sampling and industrial applications. With the advantages of relative simplicity to fabricate, low cost to operate, and well adaptability to extremely harsh conditions, the cyclone separators have become one of the most important particle removal devices which are preferably utilized in scientific and engineering fields. Since cyclones have been used extensively in various industries, a considerable number of experimental, numerical and theoretical investigations have been performed on the cyclone separators to the present. Among those, Stairmand [1] presented one of the most popular design guidelines which suggested that the cylinder height and the exit tube length should be, respectively, 1.5 and 0.5 times of the cyclone body diameter for the design of a high efficiency cy- clone. In the agricultural processing industry, 2D2D cyclone (Shep- herd and Lapple [2,3]) and 1D3D cyclone (Parnell and Davis [4]) designs are the most commonly used abatement devices for partic- ulate matter control. The D in the 2D2D designation refers to the barrel diameter of the cyclone. The numbers preceding each D re- late to the length of the barrel and cone sections, respectively. A 2D2D cyclone has a barrel and cone lengths two times the barrel diameter, whereas a 1D3D cyclone has a barrel length equal to the barrel diameter and a cone length of three times the barrel diameter. Parnell and Davis [4] first developed a 1D3D cyclone for cotton gins in an attempt to provide a more efficient fine dust collector. This cyclone design is referred to as the traditional 1D3D cyclone. Holt and Baker [5] and Funk et al. [6] conducted fur- ther experimental research on this cyclone design and reported a significant improvement in efficiency by modifying the traditional 1D3D design to employ a 2D2D inlet. This modified 1D3D cyclone design is referred to as 1D3D in this article (Fig. 1a and Table 1). Wang [7] indicated that, compared to other cyclone designs, 1D3D and 2D2D are the most efficient cyclone collectors for fine dust (particle diameters less than 100 lm). Mihalski et al. [8] re- ported ‘‘cycling lint” near the trash exit for the 1D3D and 2D2D cy- clone designs where the Particulate Matter (PM) in the inlet air stream contained lint fiber. Mihalski reported a significant increase in the exit PM concentration for these high efficiency cyclone de- signs and attributed this to small balls of lint fiber ‘‘cycling” near the trash exit causing the fine PM that would normally be collected to be diverted to the clean air exit stream. Simpson and Parnell [9] introduced a new low-pressure cyclone called the 1D2D cyclones for the cotton ginning industry to solve the cycling-lint problem. Wang et al. [7,10] studied the three afore mentioned cyclones simultaneously and they proposed a mathematical model for cal- culating pressure drop, number of active turns and D 50 for the cyclones. 0921-8831/$ - see front matter Ó 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. doi:10.1016/j.apt.2010.01.002 * Corresponding author. Address: School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran. Tel.: +98 21 88005677; fax: +98 21 88013029. E-mail addresses: H.Safikhani@me.ut.ac.ir, safikhani_hamed@yahoo.com (H. Safikhani). Advanced Powder Technology 21 (2010) 435–442 Contents lists available at ScienceDirect Advanced Powder Technology journal homepage: www.elsevier.com/locate/apt