Experimental study of free drainage of mixed cubic and spherical particles in a monolayer granular system

Abstract

The granular system of varied shapes is important in industrial production. Once the particles are deformed and crushed into parts, the characteristics of free discharge will become complicated and different from the spheres greatly. In this work, to further study the free-discharging characteristics of the mixed granular system for cubic and spherical particles, an unloading experiment of the mixed granular system is designed, with relevant experimental platforms. The algorithm for the particle recognition used in the particle tracking velocimetry (PTV) system mixed with cubic and spherical particles is applied. The effect of non-spherical particle fractions on the flow rate of discharge, residence time, and translational and rotational movement for non-spherical particles are analyzed based on PTV and the method of marked particles. It was found that a larger percentage of cubic particles has the effect of impeding particles' movement, especially in the near-wall region. The rotational movement of cubic particles becomes more intense and evident in the region below the middle of the silo. Number of contacted cubic particles during the discharge for cases when R cp0 = 10% and 15% (a), and some images during the discharge (b)(c)(d). • The discharge process of the mixed cubic and spherical particle system is analyzed. • A recognition and PTV algorithm for a mixed particle system is proposed. • Larger components of cubic particles impede the movement of the whole system. • Appropriate addition of cubic particles can locally promote the central discharge. • The rotational movement of a non-spherical particle is revealed by marked particles.