화학공학소재연구정보센터
Powder Technology, Vol.283, 266-285, 2015
Behaviors of spherical intruder in 3-D vertically vibrating granular system with vertical longitudinal air pressure wave
We investigated the behavior of a spherical intruder in a 3-D vertically vibrating small granular system. Vibration was represented as z = Asin(2 pi ft). The surface formation and the rising time of the intruder, t(rise), were proven to be influenced by both vibration and system parameters. We focused on the effects of vibration frequency: f, dimensionless accelerator: Gamma = (4 pi(2)Af pi(2))/g and air pressure inside the container at equilibrium state: p, on t(rise). A parameter y = (Gamma(2)/f(2))p was defined to describe the activation extent of small particle convection. Surface formation of the pile is more tilted, whereas t(rise), lowers, at higher y. When Gamma alone was increased, t(rise) decreased and fluctuated, and large t(rise) deviations from the average values were also observed. When Gamma or p alone was increased, or when f alone was decreased, t(rise) decreased. A vertical longitudinal air pressure wave was produced inside the pile. Mathematical model was set up to describe intruder behavior. Three forces were considered along the z-axis. The pushing-up force had the most influence on trio. Fluctuations and deviations in the t(rise)-Gamma relationship were caused by the air pressure gradient force, and the dynamical resistance force increased t(rise). (C) 2015 Elsevier B.V. All rights reserved.