摺動層をともなう流れにおける圧力損失

Abstract

The pressure loss of the flow with a moving bed is investigated theoretically and experimentally in this paper. Two kinds of experimental apparatus was used. One of them consists of three kinds of pipes of 30.8, 39.7, and 49.6mm i. d., and the other consists of two kinds of pipes of 80.2 and 105.1 mm i.d. And two kinds of glass beads and P.C.V.Pellet were used in measuring pressure loss.The pressure loss increased as the mean velocity of mixture and the delivered concentration of solid increased, but the additional pressure loss due to the presence of solid is hardly affected by the mean velocity.The data of pressure loss measured in this experiment were examined by Eq.(29), and then the relations shown in Fig. 10 and Eq.(30) were obtained.Furthermore, the force balance model above the moving bed was made in order to examine the relation between the behavior of particles and the pressure loss of the flow with a moving bed. The components of this model consist of the shear stress at the pipe wall, the shear stress at the surface of the moving bed, the shear stress due to rolling and sliding particles and the thrust forceby fluid acting on particles. The calculated values of the pressure loss by this model were in good agreement with the experimental results.It was ascertained from the result of analysis by this model that the thrust force was the dominant factor for the pressure loss, but this force decreased with an increase in the mean velocity, and it was found that this result was due to the increase of the velocity ratio of particles to fluid.