The Distribution And Motion Characteristics Of Solid Particles In Turbulent Boundary Layer

Particle-laden two-phase turbulence is widely present in nature and industry.The distribution and motion characteristics of solid particles in the boundary layer directly affect fluid flow resistance,wall wear,and solid-liquid separation efficiency.Due to the complexity of turbulence itself and the multi-scale nonlinear coupling of fluids and particles in the two-phase turbulent boundary layer of the carrier,scholars haven't conducted adequate and systematic research on the particle-laden two-phase turbulent boundary layer.Domestic study has hardly been done on this field.Therefore,the research on the particle motion characteristics in the two-phase boundary layer of the carrier particle is carried out.It is of great academic and practical value to optimize the industrial equipment and understand the two-phase turbulence mechanism.First,this paper is to set up and modify mathematical model of the particle motion equations by the Lagrangian method and implement numerical simulations of particle deposition combined with the random turbulence model.Simulation results indicate that results of the modified particle motion equation for particle deposition are reliable in particle size range1?m~100?m,relaxation time?~+<1000and density ratio?_p/?_fin the case of relatively high(gas-liquid,gas-solid).According to the calculation,the particle size is proportional to the horizontal transport distance and the particle size to the sedimentation rate;Larger particles indicate the trend of slow decline in the prediction of the sedimentation rate(?~+is about more than 30).it is in accordance with the law that the particle root mean square velocities increase with inertia,proving this trend is not related to particle jumping or re-entrainment.;it is found that the particle interception effect(?~+<10)refers to an important mechanism in particle deposition,which may help explain why particles with different mass density have different experimental data in the scattering.The paper also proves that the increase of density will increase the inertia effect of the particles and the sedimentation rate will be increase;in the region of?~+>30,calculation results with Saffma life force and deposition rate curve indicate higher consistency.So the Saffman lift must be considered when modeling;the dimensionless relaxation time?~+has a great influence on the fluctuating velocity of the particlesv?_p~+,and besides,a certain density ratio,larger particles signify worse following features of fluid.