Mechanism Research On Impact Process Between Ash Particle And Planar Surface Under Different Humidity

Gas-solid two-phase flow is a common phenomenon in industrial production and nature.Among them,the influence of inter-particle interaction on fluid in dense phase flow cannot be ignored.In order to reveal the interaction mechanism between particles,this paper mainly researches the collision mechanism between particles and plates.Single particle impacting plate is the basis for researching particle impact mechanism,which is widely concerned by scholars.Scholars mainly concentrated the dynamic characteristics of particle impact plate under dry conditions.However,few studies have been done on the dynamic characteristics of particle impact plate under humid conditions.In this paper,experimental methods and numerical methods are used to research the impact characteristics of micron scale fly ash particles and flat plate under humid conditions.Firstly,the particle dynamics theory is introduced in detail.The model of capillary force,effective gravity and drag force on particles is emphasized.This paper introduces the Hertz contact model,JKR contact model and DMT contact model,and compares the JKR contact with DMT contact model.Based on the theory of particle collision energy dissipation under dry conditions,the influence of humidity on energy dissipation of collision process is introduced.Secondly,the experimental platform of flying ash particle impact plate was set up.The influence of humidity and incident velocity on the impact process was studied.The results show that,the coefficient of restitution first increases and then decreases with the collision velocity increasing under the same humidity condition.The coefficient of restitution decreases with the humidity increasing under the same collision velocity.The critical capture velocity of particles increases with the humidity increasing.The adhesion caused by capillary force increases with the humidity increasing.The loss of plastic deformation increases with the collision velocity increasing.Finally,using ABAQUS simulate the impact characteristics of particle impacting a film/substrate system.The influence of collision velocity,liquid film characteristics and particle characteristics on the collision process were emphatically researched.The research results show that,the contact time decreases as the collision velocity increasing.The contact time change rapidly with the collision velocity when collision velocity is relatively small.The contact time change slowly with the collision velocity when collision velocity is relatively large.The coefficient of restitution decreases with the thickness of the liquid film increasing,but increases with the elastic modulus of the liquid film increasing.With the collision velocity increasing,the coefficient of restitution reaches the maximum when the particles change from full elastic deformation to elastic-plastic deformation.The coefficient of restitution increases with the particle size increasing under the same incident velocity.