A Review of CFD Modelling for Performance Predictions of Hydrocyclone

Abstract

A critical assessment is presented for the existing numerical models used for the performance prediction of hydrocyclones. As the present discussion indicates, the flow inside a hydrocyclone is quite complex and there have been numerous numerical studies on the flows and the particle motions in hydrocyclone, with a wide range of turbulence and multiphase models tested. Two-equation k-ε and RNG k-ε models flow velocities with empirical modifications were led to poor results, especially the tangential components in comparison with experimental measurements. Most of the recent studies have utilized the Reynolds stress models (RSM) with different degrees of complexity in the pressurestrain correlation. These RSM studies showed good agreements with velocity measurements. Unfortunately, the velocity profiles were not validated in most of the RSM cases where multiphase particle tracking were applied. Finally, large eddy simulation (LES) is the most advanced turbulence model applied in recent hydrocyclone numeric studies. Besides the additional information on précising the air core correctly, LES provides an additional accuracy in predicting the velocity profiles or the grade efficiency in comparison to the RSM.The multiphase models have been successfully applied in a hydrocyclone to model the Lagrangian motions of spherical particles. Eulerian-Eulerian model have been used to account for the particles effect on the fluid viscosity. Simplified Eulerian model (mixture) model predictions for solid transportation in cyclone were well predicted. Further, the inclusion of modified slip velocity calculation in the Mixture model improves the efficiency predictions close to the experimental data at low feed solid loadings. In future studies, the focus should be to model the three-dimensional flow in a hydrocyclone using at least the Reynolds stress model/LES. The particle tracking should at least include the effects of the turbulence on the particles. All these developed models will only applicable to low feed solid concentration levels. Since most of these models neglect the particle-particle interactions, a more comprehensive numerical method of modified Mixture model is applied for simulating solids flow in hydrocyclones for high feed solids concentration. Explicit models for accounting hindered settling and turbulent diffusion investigated for high feed solid concentrations in industrial cyclones are encouraging.

Non-Isothermal Separation Process of Two-Phase Mixture Water/Ultra-Viscous Heavy Oil by Hydrocyclone

“…It can be observed that near the duct underflow position, 0.135 m, the profile resembles the parabolic behavior, with the concave side up, because the temperature of the conical wall is warmer than the center of the hydrocyclone and the fluid flow is downward in this region. At the axial positions 0.275 m and 0.412 m, the temperature profiles have approximately similar behavior, because the areas of recirculation and reverse flow present in this region and this is consistent with the literature [1,11,15].…”

“…where Q α denotes heat transfer at the interface, from one phase to another phase, given by (10,11,12).…”

“…Hydrocyclone application, therefore, is limited for the particles and/or droplets bigger than 10 m [5,9]. The computational tool CFD (Computational Fluid Dynamics) provides a better understanding of the rotational turbulent flow in the interior of hydrocyclone [10][11][12]. It is a key tool for the modeling of the isothermal and non-isothermal fluid flow in a hydrocyclone.…”

Simulation of multiphase flow in hydrocyclone

“…Moreover the flow is unsteady due to the instability of the precessing vortex core. Hydrocyclone flows still present a challenge for CFD modelling due to the mentioned reasons [1][2][3][4][5][6][7][8][9][10][11][12]. It is worth noting that many features of the hydrocyclone flows are very similar to behaviour of cavitating vortex rope in draft tubes of hydraulic turbines, see [13].…”

Three-dimensional simulation of a self-propelled fish-like body swimming in a channel

“…With the development of computational technology, numerical simulations are becoming ever more important to investigate various flow phenomena. Many case studies have applied computational fluid dynamics (CFD) to these problems (Narasimha, Brennan, & Holtham, 2007;Stamou, Katsiris, Politis, & Schaelin, 2008;Wang, Reitz, Pera, Wang, & Wang, 2013). For studies of swimming fish, numerical studies have also provided insightful results, some of which may be difficult to obtain experimentally.…”