摘要
Pneumatic conveying with a diffuser is commonly used in the industry of thread locking for fasteners. During the coating operation, colloidal particles are carried by transported gas and sprayed onto surface of fasteners through a diffuser. However, accumulation of particles is frequently encountered near the outlet of the coating diffuser, which deteriorates uniformity of particle distribution on bolt surfaces. In this study, we adopt a Euler-Euler approach combined with a k-ω SST dispersed turbulence model to predict and analyze these dilute particulate flow problems. Driven by the need to understand how to avoid particle accumulation on a diffuser surface, we investigate the correlations between the Stokes number, Reynolds number, and divergent angle of a diffuser in terms of their effects on particle deposition in a diffuser. The predicted particulate flow fields can be categorized into three types: oblique flow, transitional flow, and straight flow, where the first one is regarded as the main reason for the particle accumulation. In addition, this study presents the structures of particulate flows under the influence of pertinent parameters, including divergence angles and internal baffle arrangements. Overall, the outcomes can be adopted as design guidelines and recommendations for the future development of pneumatic conveying in coating diffusers.