Study On The Interaction Between The Storage Material And The Silo Wall During The Unloading Process Of Curved Funnel Silo

When the silo is unloading,the dynamic pressure on the silo wall is the key factor leading to structural damage,and the arching of the storage material is an important reason for increasing the dynamic pressure.During the unloading process of the traditional conical funnel silo,the storage material is prone to tubular flow,resulting in arching.The curved funnel silo can improve the discharge flow state,reduce the pressure arch strength of the storage material,thereby reducing the dynamic pressure on the silo wall during discharge.Based on the National Natural Science Foundation of China（Grant No.51578216）,this paper uses experiments and discrete element simulation methods to study the flow pattern of curved hopper silos and the dynamic pressure and distribution on the silo wall,and compare with conical hopper silos.On this basis,the calculation formula of the particle flow rate above the side wall of the funnel is derived,combined with the particle flow velocity field,the reason why the curved funnel improves the discharge flow state is.Using the theory of pressure arch,the reason for improving the flow pattern of the curved funnel silo,reducing the instantaneous arch strength,and reducing the dynamic lateral pressure of the silo is studied.And the decompression mechanism of the curved funnel silo is revealed.The specific research content and main conclusions are:（1）The curved funnel silo and the conical funnel silo with the funnel inclination angles of30°,45° and 60° are selected,and the conical funnel silo and the curved funnel silo are respectively studied and analyzed through the method of experiment and simulation.The relationship between the maximum dynamic lateral pressure and the flow form of the stored material during the unloading process is analyzed.It can be seen that when the flow form of the conical funnel silo is tubular flow,the dynamic lateral pressure is relatively large;the flow form of the curved funnel silo is integral flow,the dynamic lateral pressure is relatively small.It shows that the curved funnel can improve the flow form of the storage material,thereby reducing the maximum dynamic lateral pressure of the silo.（2）During the test and simulation process,the distribution range of the larger dynamic pressure during the unloading process of the two silos was summarized,and the relationship between the two was analyzed by combining the area of the dead material area obtained during the simulation process.It can be seen that the dead material area of the conical funnel silo is larger,and the larger side pressure is concentrated on the bottom of the silo.The dead material area of the curved funnel silo is much smaller than that of the conical funnel silo and the phenomenon of concentrated distribution of pressure on the larger side is avoided.（3）Based on the silo standard,the formula for calculating the particle flow rate above the side wall of the funnel is derived,and the calculation results of the two silos are compared and analyzed,the result shows that during the unloading process,the particles above the side wall of the conical funnel are easy to accumulate to form a dead material area,which leads to the formation of a tubular flow of the material.While the particles at the side wall of the curved funnel accelerate from top to bottom to flow toward the discharge port,avoiding the formation of a large area of dead material area,and effectively improving the storage material flow form.Combining the relationship between the force chain and the arch,through the analysis of the dead material area and the instantaneous arch,the influence of the dead material area on the larger dynamic pressure distribution is studied,the result shows that the instantaneous arch is easy to form within the height range of the dead material area,making the larger dynamic lateral pressure concentricity appear.The curved funnel silo has a relatively large dynamic pressure distribution range due to the smaller dead material area.（4）Based on the theory of pressure-bearing arches,the relationship between the angle between the instantaneous arch toe and the horizontal direction,the bearing capacity of the instantaneous arch and the instantaneous arch inertial force in the two funnel silos is studied,and the following conclusions are drawn: in the conical funnel silo,the angle between the instantaneous arch foot and the horizontal direction is large,and the instantaneous arch bearing capacity is strong,which causes the instantaneous arch to generate a large inertial force during the arching and breaking process.The inertial force of the instantaneous arch directly affects the size of the dynamic lateral pressure of the silo,so the curved funnel improves the flow pattern,reduces the angle between the instantaneous arch foot and the horizontal direction,reduces the instantaneous arch bearing capacity.Then the inertia force generated by the instantaneous arch during arching and arch breaking is reduced,so as to achieve the purpose of reducing the dynamic lateral pressure of the silo.