Dynamics Of Irregular Particles In A Rotating Drum As Revealed By Speckle Visibility Spectroscopy

Particle matter is ubiquitous in nature.Scientists generally define size of 1 micron or above particle in the discrete system as particulate matter.Particle matter change states in the external and internal force,the movement which is similar to fluid called particle flow^[1.2].Phenomena such as avalanche,dune evolution,debris flow and industrial discrete material,all belong to the particle flow^[35].A large number of literatures have discussed the movement and principle of granular flow in horizontal cylinders.However,most of the current discussions are focused on spherical particles.Different particle sizes and shapes have a great influence on the particle characteristics.In practical applications,the processed materials such as industrial rotary kilns and conveyor belts,are irregular particles.Therefore,the study of the effect of particle shape on its motion characteristics has far-reaching practical significance.In order to study the effect of shape on the motion characteristics of granules,this paper studied the movement pattern of irregular glass sand with the diameter of 1¹.5mm in the horizontal drum by means of dynamic speckle spectroscopy and image analysis.The comparison of the movement patterns of the irregular particles and the glass beads also discussed under the same conditions,the main research work includes:·The mechanics model of microscopic discrete particles,meso-scale andmotion model of granular flow at macroscopic scale are studied.·The particle temperature,which characterizes the overall mean particlevelocity fluctuation,is studied in detail,and measured by speckle visibility spectroscopy.A dual SVS system with two measuring channels is proposed,and make the two measuring systems synchronize by cross correlation algorithm.·The suitable experimental facilities including horizontal roller,mechanicalmechanism and double SVS measuring light path are set up.The appropriate experimental particles are selected and the shape and size distribution of the particle are studied with high precision microscope and image processing.·The experiment data were analyzed and summarized,and the motioncharacteristics of the irregular particle flow in the horizontal drum were obtained.