Sensibility Study of the Reynolds Stress Model Parameters for Swirling Flows in Cyclones

Abstract

Several studies found in the literature apply Computational Fluid Dynamics (CFD) for the swirling flow in cyclones, such as Costa et al. (2013) who studied solid-solid interactions, and Sgrott Jr. et al. (2013) that investigated a technique for cyclones’ project optimization. The main characteristic of this flow is the anisotropic behavior of the turbulence due to the highly swirling gas flow. In this sense, a turbulence model with capability to predict the swirling flow, such as the Reynolds Stress Model (RSM), must be applied. This model has been used in numerous studies of cyclones and the results showed that the model is well suited to predict the pressure drop and the axial velocity component of the flow. However, for the tangential velocity component the results were not satisfactory for quantitative validation. Based on a comparison of numerical and experimental results, and knowing the importance of the axial and the tangential velocities for the efficiency of collection in cyclones and for the pressure drop, the latter which is related to energy costs; the main objective of this study is to present a sensibility study of the Reynolds Stress Model parameters for swirling flow in cyclones. To perform this study, a CFD commercial code was used to simulate cases based on a 2n-3 factorial design. In this design, seven parameters of the RSM-SSG model (C1, C1*, C2, C3, C3*, C4 and C5) were varied 5% above and below their standard values in order to analyze the effect of each parameter in the pressure drop and in the axial and tangential velocity profiles in cyclones for the gas phase flow. The results showed that the parameters C1 and C1* have more influence in the pressure drop and the parameters C3 and C3* have more influence in the axial and tangential velocity peaks.