Large Eddy Simulation of Swirl Topology Evolution in Strong Oxidant Jet Milling Force Field

Abstract

In this paper, Large Eddy Simulation (LES) is employed to investigate the evolution characteristics of a spiral jet mill. This study aims to provide a theoretical reference for the numerical simulation and design optimization of spiral jet mills. To evaluate the influence of grids on simulation accuracy, grid convergence index (GCI) analysis was carried out on three sets of non-structural grids with equal proportion refinement. The visualization results demonstrate that the feeding gas traction and jet impact attenuation contribute to momentum conversion from the edge to the central domain, facilitating the development of the central swirl. The cross-scale chamber structure makes the turbulent coherent structure in the swirl evolution tend to be complex and disordered. A large-scale annular swirl is formed by stacking and winding multiple strip vortices. By comparing with the steady-state solution calculated using the k-epsilon model, it is confirmed that the aerodynamic characteristics in the micronization chamber stabilize at 400 ms. At this time, the combined action of the radial and tangential velocity forms a spiral airflow trajectory.

Keywords

• swirl topology
• flow characteristic
• heat transfer
• coherence vortex
• large eddy simulation