Experimental and theoretical analysis of large particle–wall collision with different metal plates

Abstract

The coefficients of restitution are important parameters in the study of particle–wall collision, which is widely used in discrete element modeling in solid–liquid multiphase systems. To improve the accuracy of numerical simulations, correspondingly exact particle–wall collision parameters are needed. The current models used in numerical simulation, however, are mostly suitable for solid–gas systems, in which collision models used to be micro-sized. Millimeter-size particle–wall collision models in wet experimental conditions and research on the influence of plate materials were lacking. In this study, we designed an experimental system focused on the different materials of the particles and collision plates and the dry or wet experimental environment to discuss the change of restitution coefficients in various conditions. We selected millimeter-sized iron 45 particles and glass particles, which represented plastic material and hard brittle material, respectively. We also selected three industrial metals, HT250 gray cast iron, 6061 aluminum alloy, and 316 stainless steel, which are commonly used in hydraulic machinery, for the collision plates. Experiments were performed to measure the incident and rebound velocities of the particle at various impact angles. In this paper, we have provided and compared the results of restitution coefficients of velocity and angle varying with the approach angle. In the processing of the experiment, we used the control variate method and applied an ultra-depth of field three-dimensional microscope to scan the surface of the collision plate. In the analysis of the experimental results, single particle–wall collision was seen as a non-smooth dynamical system to discuss the specific phenomenon. Finally, we obtained the relationship between the restitution of normal velocity and elastic elements of materials and explained the relationship of stick–slip motion with the approach angle and velocity.