抄録
The pressure drops, when the velocity of particles accelerated by the air current increases from zero to the terminal velocity while passing through a vertical pipe, were observed and photographed. The experimental apparatus is shown in Fig.1. The results are shown in Fig.2∼Fig.9, inclusive. The pressure drops at the lower pipe, where the particles are mixed, are particularly large, which cannot be negleted when the system is design. We have explained the results theoretically by our way in which we classified pressure drops into three parts, that is, the pressure drop due to accelerating particles, that due to the fiction loss of air and the static pressure difference.
