Research On The Characteristics And Formation Mechanism Of Directional Bulk Material Flow Driven By The Horizontal Trough-Free Screw

The flat bottom silo increases the space utilization rate of bulk material storage,saving40%of the floor area compared to outdoor stacking.The horizontal trough free screw is the main spreading/discharging equipment in flat bottom silo,with a high degree of automation.It also increases the types of bulk materials that can be stored in the silo,expanding the range of use of the silo.The stable,controllable,and efficient directional material flow on the static material surface is driven by a horizontal trough free screw.The material flow with long and dense contact of material particles is a problem of large deformation and the movement of continuously inputting energy from the outside,with obvious multi-scale characteristics.The formation mechanism and characteristics of directional material flow are currently urgently scientific and practical problems to be solved,which is an urgent scientific and application problem to be solved.The mechanism of controlled motion of particles driven by external force has been one of the hot topics in the field of science in the past 20 years.The theory of bulk material flow formed in this study involves interdisciplinary research,which can not only be used for the design and manufacturing of horizontal trough–free screw to enhance the ability of large-scale material spreading and discharging in flat bottomed silos in China,but also supplement and enhance the basic theories in the analysis and prediction of geological disasters,mineral mining,and large-scale controlled movement of materials.This paper combines the methods of theoretical analysis,simulation,and experimental verification to systematically study the mechanism of efficient directional bulk material flow driven composite excitation.Particles are in close contact and transfer forces in directional bulk material flow.From a mesoscale perspective,in a complex mechanical system with a large number of discrete particle interactions,a non-uniform contact force network is formed between particles,and the motion of individual particles is highly random,making their behavior difficult to predict;From a macroscale perspective,the directional bulk material flow has obvious regularity,forming a material flow that moves along the spiral axis under self-organization.Directional material flow cannot be analyzed solely from a single scale.However,existing experimental methods are difficult to obtain the motion patterns of particles below the surface layer,and discrete element simulation has become an essential research method.At a macroscale,the mass flow rate,effective conveying rate,torque and power are analyzed,and the laws of material movement is studied.The lowering depth and translational velocity affect the mass flow rate by changing the feeding mass and effective conveying rate,while the rotational velocity only affects the mass flow rate by changing the effective conveying rate.When the n>360r/min,the effective conveying rate hardly increases.The formula for calculating the mass of group 1 material is deduced and verified.The mass increase factor of each material groupα_i is expressed as a function of group 1,when the h _L∈[9,27],α_i hardly changes with changes in h _L.Within each material group,there is a logarithmic relationship between the height of the material on the reclaiming side and the mass of material group,and is not related to the combination of translation velocity and lowering depth;After the n increases,the height of the material on the reclaiming side also increases.Based on the above analysis,the interpolation method is used to obtain the operating parameter selection diagram of the screw.However,different combinations of operating parameters can yield the same macroscale appearance,and further research is needed on their mesoscale motion characteristics.At a mesoscale,statistical theories are introduced to analyze data such as displacement,velocity,and contact force of material group.The v_p and n are the main factors affecting the displacement and axial velocity of the material,respectively.When the n≤240r/min,the contact force is only related to the mass of material and the n.When n>240r/min,the velocity of the material group exhibited a bipolar distribution rather than uniform gradient transition,resulting in abnormal increase in contact force and higher energy consumption,which limits the increase in rotational velocity.The characteristics of the material flow field are extracted at both macro and mesoscales,and the main factors affecting the directional bulk material flow are analyzed.The formation conditions of the directional bulk material flow are obtained,and adjustment methods are proposed to ensure its stable and efficient operation.Finally,a mechanism of efficient directional bulk material flow driven by screw is formed.This article conducts research on the flow mechanism of material under specific conditions,which is a new research topic in bulk mechanics.It can fundamentally understand and master the process of changes in the material flow field and the complex rheological motion laws when the external environment changes,which has significant scientific significance and application prospects.