Pressure Loss Reduction due to in a Pipe Mixing Flow of Coarse Particles

Abstract

In a flow of solid-particle/water mixture in a circular pipe with a 77 mm diameter, the concentration of particles was varied continuously. The flow rate, the hydraulic gradient and the solid fraction were measured. Two kinds of plastic-beads with different densities and sizes were used as the sample. The conclusions are summarized as follows. (1) The pressure loss reduction effect due to the mixing of particles can be caused whether the density of particles is greater or smaller than that of water. (2) The reduction ratio of the hydraulic gradient is represented roughly as a function of the relative solid fraction and the Froude number F_d referring to the particle size. (3) The pressure loss reduction effect occurs when F_d>2000, and the maximum reduction ratio attained in this work is about 7%.