CFD modelling of a powder spraying nozzle used for dry coating

Abstract

The aim of these studies was to examine the suitability of the Euler–Lagrange approach for modelling the powder spraying process performed with a pneumatic nozzle used for dry coating in spout-fluid bed apparatus. Simulation results were validated using the digital PIV (Particle Image Velocimetry) method and measurement equipment constructed by the authors. The validation process led to the determination of the optimal Ansys Fluent solver settings, which ensure a satisfactory accuracy of the simulation results (the average relative error of all simulation points at the level of 10.5%). The experimental results are most accurately reflected by simulation results obtained with the use of the standard k − ε model that has the discrete random walk (DRW) model activated. The detailed analysis of the operation of the spout-fluid bed apparatus allowed for the examination of the influence of hydrodynamic parameters (the mass flow rate of the gas spraying the powder and plasticizer, as well as spouting gas) on the velocity and concentration of the dispersed phase in the device. The scientific investigation covered the analysis of the velocity profiles and the volume fraction of the coating powder in different zones of the column.