Abstract
To investigate the flow characteristics with the steady state pneumatic transportation of solids in horizontal pipes at low air velocities, in this paper, instantaneous photographs of solid flow patterns were taken with a camera simultaneously operated with a storoboscope. The experimental results were as follows: solids tend to settle out along the bottom of the pipe and form dunes at a periodic interval. The height and the length of each dune under such condition is related to the solids-gas flow ratios, as well as to air velocity. However, when the solids-gas ratios are more than 10, these values become constant independently of the solids-gas ratios. On the other hand, the angle of slope, and the pitch length of each dune are independent of the extent of air velocity and solids-gas ratios.
