Study on Motion and Deposition of Particles in a Wind Tunnel

Study on motion and deposition characteristics of particles in a wind tunnel is important for understanding particle transfer in ventilation duct flows. Firstly, polydisperse particles with smaller mean diameter were taken as tracers for airflow velocity test in the wind tunnel under ventilation case and airflow velocities were measured by a Particle Image Velocimetry (PIV) system. Then, the average velocity contours of the particles with the mean (median) diameter of 25 μm were determined by the PIV. Next, the relative concentration contours were analyzed for the particle phase at the different test sections. Finally, deposition rates of the particles were determined to the various surfaces in the wind tunnel. The experimental results indicate that PIV can accurately measure the two-dimensional airflow velocities and there is a difference between air and particle phase velocity contours. The smaller the airflow velocity is, the weaker the particles follow the airflow is. During the transfer of the polydisperse particles along the flow, the stratification of relative concentration of the particles along the height seems to take place. The deposition rates of polydisperse particles to the floor are higher than that to the wall and ceiling. For polydisperse particles, the mean diameter, size distribution, and spread parameter should have a comprehensive impact on the floor, wall and ceiling deposition.