A Study of Effect of Horizontal Vibrations on Granular Flow in Conical Hopper Using Discrete Element Method (DEM) Approach

Effect of horizontal vibration on gravity flow of granular material from conical hopper is modeled using the Discrete Element Method (DEM) and are validated by comparison with experiments performed by the authors (Hunt et al. 1999). The authors used the mono-sized granular system of particles, but most of the granular mixture in industry is multicomponent having different composition. The impact of such material variability and improper tuning of vibration parameters during vibratory hopper discharge can result in poor quality by enhancing segregation and unpredictable discharge behaviour. In this context, the present investigation is extended to explore the behaviour of multi-component mixtures under different horizontal vibration conditions. Different mixtures were prepared by the combination of different diameter particles on mass basis. The influence of factors, such as vibration frequency, acceleration amplitude, fine percentage in mixture, diameter ratio, multicomponents mixtures (binary and ternary), and cohesion between particles on mass flow rate and segregation during the vibratory discharge processes are studied. The extent of segregation is calculated by means of mass fraction of fines inside hopper for different operating conditions. The numerical results indicate that with the increase in vibration acceleration amplitude at a fixed frequency; give rise to increased mass flow rate and there exists acceleration amplitude beyond which segregation is much predominant. Furthermore, the particles rearrangements and velocities are tracked to investigate the role of vibrations during hopper discharge. The spatial distribution of the velocity profile indicates that different mixtures behave differently at a particular vibration condition. The phenomena like sieving or percolation are also obtained based on the analysis of top view simulation snap shots. In addition, vibration effects by applying cohesion between the particles significantly reduce the mass flow rate. For a particular vibration parameter, cohesive mixture shows different discharge behaviour as compared with cohesion less mixture. Mixture components also have a great part to play for segregation and binary mixture suffers more segregation as compared to ternary mixture. Eventually this study emphasizes the importance of proper vibration parameter and provides first estimate of effect of vibration parameters and material attributes on mass flow rate and segregation during vibratory hopper discharge.

Keywords: Horizontal vibrations; Mass discharge rate; Segregation; percolation; Cohesion