Numerical Simulation Of Material Flow Pulsation At The Outlet Of Screw Conveyor

The screw structure and its rotary motion in the screw conveyor make the material flow out of the outlet to have a periodic change in the flow rate,that is,flow pulsation.It does not have much impact on conveying materials,but when used for dosing and batching,it will affect the quality of the production process and cause energy waste.At present,the research on the structural design of the screw conveyor is still insufficient,and the research on the influence of the structure form,parameters and working conditions of the screw conveyor on the flow pulsation is still lacking,and the reasons for the material flow pulsation have not been clearly explained so far.Therefore,it is of great engineering significance and practical value to carry out research on the material flow pulsation at the outlet of the screw conveyor.At present,the Discrete Element Method based on particle orbit method has become an important tool to study granular flow,which can obtain near-real particle motion state and detailed particle motion information.In this paper,based on the Discrete Element Method,EDEM is used to simulate the flow process of spherical particles in a screw conveyor.The flow state of the material in the trough and the flow rule of the outlet are studied.It is confirmed that the material blocking by the screw is not the main reason for the flow pulsation,and the periodic uneven distribution of the material in the trough is the main reason for the flow pulsation.It is proposed to use the structure of shaftless screw conveying,large pitch screw conveying,double-axis screw parallel conveying and inclined outlet structure to reduce the flow pulsation of the material at the outlet.The pulsation is smaller,the flow pulsation of the material at the outlet of the screw conveying is smaller,and the flow pulsation of the material at the outlet of the double-axis screw conveying is smaller than that of the single-axis screw conveying,and the structure of the inclined outlet is smaller than that of the normal outlet.The flow pulsation of the material at the outlet is smaller.The average pulsation value is defined to represent the size of the material flow pulsation,and the influence of the structure,parameters and working conditions of the screw conveyor on the flow pulsation is studied.As the coefficient increases gradually,the flow pulsation gradually decreases.With the gradual increase of the pitch,the flow pulsation shows a trend of first decreasing and then increasing.When the difference angle between the two helixes in the double-shaft screw conveyor changes from 0° to 360°,the flow pulsation first decreases and then increases.When the difference between the two helix angles is 180°,the flow pulsation reaches the minimum.In summary,this paper explains the reasons for the pulsation of material flow at the outlet of the screw conveyor,proposes a new method to reduce the flow pulsation,and obtains the influence of the changes of various parameters on the flow pulsation.The research results can be used to guide the structural design and working condition selection of the screw conveyor,and provide technical guidance for the promotion and use of the screw conveyor in the occasions of quantitative feeding and batching.