Investigations of Gas–Particle Two-Phase Flow in Swirling Combustor by the Particle Stokes Numbers

Yang Liu,Guohui Li

doi:10.3390/pr9060951

Abstract

Gas turbulence modulations and particle dispersions of swirling gas–particle two-phase flow in the combustor is investigated under the large spans of the particle Stokes numbers. To fully consider the preferential concentrations and anisotropic dispersions of a particle, a kinetic frictional stress model coupled with a second-order moment two-phase turbulent model and granular temperature equation is improved. The proposed modeling and simulations are in good agreement with the experimental validations. Results show turbulent modulations and particle dispersions exhibit strongly anisotropic characteristics, keeping a close relationship with flow structure. The axial gas velocity and RMS fluctuation velocity of 45.0-μm EGP was approximately 5.0 times and 3.0 times greater than 1000.0 μm Copper particles, and their axial particle velocity was 0.25 times and twice greater than those of 45.0 μm EGP. The degree of modulation in the axial–radial direction is larger than those of radial–tangential and axial–tangential direction. Particle dispersions are sensitive to particle diameter parameters and intensified by higher Stokes number.

Highlights

Gas–particle two-phase turbulent flow in swirling combustor have been employed widely in the fields of industrial processes, e.g., chemical engineering, aerospace engineering, and biotechnology engineering
Computational fluid dynamics (CFD) methods are being utilized substantially compared to hydrodynamic modelling for the single/multicomponent gas–particle two-phase turbulent flow, e.g., the direct numerical simulation (DNS) algorithm [6,7,8,9,10,11], large eddy simulation (LES) SGS model [12,13,14,15,16,17,18], and Reynolds time-averaged Navier–Stokes simulation (RANS) [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34]
Gas turbulent modulations are highly sensitive to mass loadings rather than particle response, which is the primary order from a group of parameters: particle size, density, swirling number, etc

Summary

Introduction

Gas–particle two-phase turbulent flow in swirling combustor have been employed widely in the fields of industrial processes, e.g., chemical engineering, aerospace engineering, and biotechnology engineering. As for LES SGS modeling, Apte et al (2003) [13] and Oefelein et al (2007) [14] simulated the swirling particle-laden two-phase turbulent flow in a coaxial-jet combustor based on the Sommerfield’s experiment [37] The hydrodynamic parameters such as particle dispersions, residence time under different diameters, and evolution of coherent structures were predicted. Pakhomov et al (2015) [24] proposed a Reynolds stresses model for gas–particle turbulence flow and revealed that gas turbulent modulation can be attenuated by fine particles, reaching up to 25% for swirling particle dispersions. Zhou et al (2017, 2018) [29,30] and Liu et al (2019) [31] established and developed a set of second-order moment gas–particle turbulent models to successfully reveal the anisotropic dispersions of discrete particle and bubble phases, as well as the hydrodynamics of swirling two-phase flows [32,33,34]. The two-phase anisotropic behaviors, Reynolds stresses redistributions, and mixing and separation characteristics were indicated

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Conclusion