Analysis of Numerical Modelling of Turbulence in a Conical Reverse‐Flow Cyclone (original) (raw)
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Advanced Powder Technology, 2021
Numerical study of the fluid flow and particle dynamics is presented by numerical techniques to charac-29 terize the performance of new design cyclone separators with one, two and three tangential inlets. The 30 design of this cyclone is based on the idea of improving cyclone performance by increasing the vortex 31 length. This cyclone differs from a conventional cyclone with the separation space. Instead of conical part, 32 the separation space of this cyclone consists of an outer cylinder and a vortex limiter. The Reynolds aver-33 aged Navier-Stokes equations with Reynolds stress turbulence model (RSM) are solved by use of the 34 finite volume method based on the SIMPLE pressure correction algorithm in the computational domain. 35 The Eulerian-Lagrangian computational procedure is used to predict particles tracking in the cyclones. 36 The velocity fluctuations are simulated using the Discrete Random Walk (DRW). In the results the effects 37 of number of inlets on the different important parameters such as pressure drop, collection efficiency, 38 axial velocity and turbulence are investigated and deeply discussed. Contours of velocity, pressure and 39 turbulent kinetic energy within these cyclones with different number of inlets are shown. The results 40 show that the cyclone with three inlets has more collection efficiency, less pressure drop and less turbu-41 lence distribution with respect to cyclones with one and two inlets which is good in cyclones perfor-42 mance. Generally it is recommended to use the new cyclone designs with higher number of inlets. 43
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2000
The conventional design of the cyclone model has been used without significant modifications for about a century. Recently, some studies were carried out to improve equipment performance by evaluating the geometric influence of the tangential inlet section and scroll inlet duct design. In this work, the influence of cyclone inlet section geometry was studied using an angle of 45 degrees
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Jurnal Teknologi, 2016
A numerical simulation technique was employed to model the two phase flow in cyclones using computational fluid dynamics (CFD). Three different inlet angles of cyclone, including 45, 0 and-45 degrees were compared to describe the efficiency of the conventional cyclone with the modified inlet angle ones. The results showed that the interaction between solid particles in dilute system could be neglected. The pressure drop was decreased when the inlet angle of the cyclone increased. The cyclone with 45 degrees inlet angle tended to have the lowest pressure drop. The collection efficiency was improved with 45 degrees inlet angle due to high swirling motion of gas flow.
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Numerical analysis of flow characteristics and separation efficiency in a high-efficiency cyclone has been performed. Several models based on the experimental observation for a design purpose were proposed. However, the model is only estimated the cyclone's performance under the limited environments; it is difficult to obtain a general model for all types of cyclones. The purpose of this study is to find out the flow characteristics and separation efficiency numerically. The Reynolds stress model (RSM) was employed instead of a standard k-ε or a k-ω model which was suitable for isotropic turbulence and it could predict the pressure drop and the Rankine vortex very well. For small particles, there were three significant components (entrance of vortex finder, cone, and dust collector) for the particle separation. In the present work, the particle re-entraining phenomenon from the dust collector to the cyclone body was observed after considerable time. This re-entrainment degraded ...
Chemical Engineering Science, 2016
The paper investigates the confined swirling flow in a cyclone. The numerical simulations are performed using a proposed eddy viscosity turbulence model, which accounts for the effects of the streamline curvature and rotation. This distinguishes the current model from the conventional Eddy Viscosity Models (EVMs) that are known to fail to predict the Rankine vortex in swirling flows. Although computationally more expensive approaches, the Reynolds Stress Model (RSM) and Large Eddy Simulation (LES), have demonstrated a high capability of dealing with such flows, these techniques are often unsuited for use in complex design studies where computational speed and robustness are key factors. In the present approach, the Shear Stress Transport with Curvature Correction (SSTCC) turbulence model is modified by the introduction of the Richardson number to account for the rotation and curvature effects. The numerical predictions were validated using experimental results and also compared to the data obtained using the RSM model and various EVMs without the proposed modifications. The investigations started with a benchmark case of a flow through a channel duct with a U-turn, after which more challenging simulations of a high swirling flow within a cyclone separator device were performed. The results show that the proposed model is competitive in terms of accuracy when compared to RSM and proves to be superior to the RSM model in terms of computational cost. Furthermore, it is found that the proposed model preserves the ability to represent the Rankine vortex profile at different longitudinal levels of the cyclone. It is also more efficient in terms of the computational cost than the SSTCC model without the introduced modifications.