Study On The Effect Of Wall Properties On Adhesion Characteristics Of Particles

The deposition of solid particles in pipes is an important industrial phenomenon.The particles contained in the airflow are easily collided with the wall due to gravity,inertia and turbulence in the near wall of the tube so that they are separated from the gas and cause pipe blockage and other hazards.So the study of the adhesion characteristics of particles on the academic and engineering guidance is of great significance.In this paper,the adhesion characteristics of particles between 0.01 ~ 50 ?m was simulated numerically.The rough wall was simulated by square rough elements.The Reynolds Stress Model of the turbulence was selected to simulate the velocity distribution and the turbulence in the near-wall region.The results showed that regular square rough elements made the flow field in the near wall region wave shape,the turbulent kinetic energy near the wall increased with the increase of roughness and a large eddy was generated between two rough elements.Then the influence of particle parameters on the collision characteristics was investigated by DEM method.The relation between the friction coefficient and the angle of incidence was found,and the friction coefficient curve was fitted.The motion of particles was investigated by using a Discrete Random Walk model,and the effects of wall properties,gravity and air velocity on the adhesion characteristics of particles were investigated.Finally the POD method was used to predict the deposition rate rapidly.The results showed that roughness had a great influence on the motion of particles.Most particles collided with the wall and caused adhesion or rebound,but only the deposition rate of small particles was obviously affected.The factors that mainly affected the deposition rate were gravity,inertia,velocity and the wall rebound.When the particle diameter was larger than 10 ?m,the deposition rate decreased with the increase of the gas velocity,and the wall rebound was the main reason for the decrease.Compared with the numerical simulation method,the POD method was only less than 1% error and could save at least 1800 times the calculation time.So POD was a good method to simulate the particle deposition quickly and accurately.