Thermophoretic Depositon And Re-entraniment Mechanism Of Soot Particle

Motor vehicle particle have a great threat to people's health due to their fine size and toxic compositions. As the holding of vehicles increasing, particle pollution has become a serious problem to be solved. Analysis the mechanism of thermophoretic deposition, turbulent deposition and the re-entrainment of soot particle may bring much more profound understanding of the characteristic of particle movement in exhaust pipe, and also provide a new way for soot particle control, particle purification and improvement of particle size distribution.This is the main work:Analyze the law of particle transport and deposition in a simulation of turbulent tube flow with FLUENT software. Temperature field and turbulent kinetic energy field are researched in this part, under conditions of different tube geometry dimension, different inlet velocity and temperature. During the course of researching on thermophoretic deposition, influence of turbulent edd is also taken into account enough, also, thermophoretic particle deposition and turbulent deposition are compared.Influence of three different kinds of tube entrance to thermophoretic deposition in laminar flow is investigated in this part; Combine the idea of critical particle trajectory and field parameters for developing flow and developing temperature, and developed flow but developing temperature simulated by FLUENT, critical particle trajectory r_c is gained by solving particle equations of motion, and obtain the deposition efficiency ulteriorly; For the condition of both flow and temperature are full developed-there the critical particle trajectory is gained by analytical method; Compare the different impact of three entrance to thermophoretic deposition efficiencyLaw of the re-entrainment of deposited particles is investigated. In this part, several classical adhesion models are compared and discussed. Synthetically consider all kinds of factors which influent re-entrainment of deposited particles, and further establish and solve the critical detachment model, and analyze the influence of flow velocity, particle diameter on the re-entrainment of deposited particles .By the research work upwards, in the range of this paper, the characters of particle deposition in turbulent tube and the influence of the three different kind entrances to thermophoretic particle deposition in laminar flow are obtained, and also gain the characters of particle re-entrainment in different conditions.