Effects of particle size and liquid film viscosity on characteristics of particles colliding with dry and wet walls

Particle-wall collisions frequently occur in fluidized beds, granulation processes, and the transportation of gas–solid two-phase flows in pipelines. Exploring the rebound characteristics of particles after colliding with the wall will enable more accurate calculation models of collision rebound, enhanced control of the collision–rebound process, and improved efficiency of industrial production. This paper studies the relationship between the energy consumed by the liquid film and the energy consumed in the collision and investigates the effects of different particle sizes and liquid film viscosities on the liquid bridge morphology, coefficient of restitution (COR), and critical capture angle (CCA). The results show that the normal COR is affected by particle size, incident velocity, and viscosity, while the tangential COR is only related to the existence of the liquid film. Additionally, the maximum size of the liquid bridge and the growth rate of COR change suddenly in a transition region. The particle size and liquid film viscosity have significant effects on the CCA of the particle. The numerical results enable us to propose a general form of the normal wet collision model.