Experimental research on velocity distribution of PM2.5 in a rectangular channel

Flow condition of PM_2.5 was investigated through experiments in a rectangular channel. Particle dynamic analysis (PDA) equipment was adopted to measure the velocity field of PM_2.5 in the cross-section of channel on line. Radial velocities and axial velocities of the particles were measured on condition with different entrance temperature in different points of the flow domain within the channel, and flow velocity field was obtained. It is shown that velocity distribution varied with the distance between the particle and the water-cooled wall within the boundary and field which is near the boundary. So that, the domain can be classified into three regions: the main velocity region, the low velocity region that flow velocity less than the main velocity and the high velocity region that flow velocity higher than the main velocity. In the rectangular channel, axial velocity of PM_2.5 inclined to the stream because of velocity excursion on the main flow direction, and radial velocity of PM_2.5 may fluctuate from plus to minus induced of vortex shedding and thermophoresis. Meanwhile, the smaller distance that particle from the bottom or the center axes, the larger of fluctuate range. Radial velocity of particle is key parameter which can affect thermophoresis and depositions of PM_2.5 follow the gas flow.