Numerical study on the transformation mechanism of rice discharging characteristics of double-orifice silo

Multi-orifice silos are used in a wide variety of applications due to their ability to increase discharging rate and reduce clogging probability. However, the discharge characteristics of multi-orifice silos are more complex than that of single outlet silos. Double-orifice eccentric silos are the most basic form of multi-orifice silos, as multi-orifice silos can be regarded as a combination of multiple double-orifice silos. Eccentric silos refer to those silos with eccentric discharge. In this work, the transformation mechanism of particle flow characteristics inside the fundamental double-orifice silo was numerically investigated. A method for determining special position of dynamic arch transfer above orifice according to the fluctuation change of arch feet pressure was proposed first. The results showed that there are obvious differences in the contact and flow characteristics of particles flowing to both sides of double-orifice silos at different stages. Free-fall arch (FFA) structure undergoes three transitional stages, with eccentricities of 0.2 and 0.327 serving as critical transition points, corresponding to the stage transition points in discharge rate at eccentricities of 0.205 and 0.33. Phase change in discharging process originates from the shear interaction between flowing particles and particles in quasi-stagnation region between orifices. Furthermore, as the quasi-stagnation region expands, the impact on outflow particles is first dramatically weakened, then slowly weakened and finally remains stable, corresponding to different particle outflow transformation stages. The results can contribute to the deeper understanding of complex particle discharge problems in multi-orifice silos and provide theoretical guidance for the application and design of multi-orifice silos.