The Behavior Of Fine Particles In The Flow And Temperature Boundary Layer

The primary objective of the study was to solve the low efficiency of the industrial dust catcher in catching the fine particle. By analyzing the experiment data and numerical simulating of the gas-particle two phase flow, the possibility of using thermophoresis to precipitate dust was studied. The results instructed further utilization of thermophoresis in industrial of fine particle catching.The experiment data of the gas-particle two-phase flow in horizontal duct was been analyzed. The axial velocity, fluctuation velocity, the turbulence intensity, and transverse velocity of the fine particle were studied. The results showed that the turbulence intensity and turbulent energy of the two-phase flow increased while the transverse velocity decreased in the presence of the temperature difference. Larger changes were measured in the near wall region. The numerical simulating results of the gas-particle two-phase flow in duct show that the velocity difference of the gas and particle in the near-wall region would increase as the diameter of the particle enlarge. The Saffman force does not affect the axial velocity of the flow, while it change the concentration of the particle.The gas-particle two-phase flows in the present of temperature were also numerical simulation. The temperature field along the axis, axial velocity, the turbulent energy, and the concentration of the particles were investigated when the temperature field varied. The numerical experiment shows that the thermophoresis force changes the concentration of the 2-micron particle, decreasing in the main flow and increasing in the near-wall region. The temperature gradient and concentration gradient were both large in the near-wall region. Although the thermophoresis force could affect the 50-micron particle, the concentration did not change as large as 2-micron particle because of the large mass and the wall effect. By increasing the wall temperature, the temperature difference reduced. The greater the temperature differences, the larger of the concentration of the 2-micron particle.