Pressure Drop Reduction of Liquid-Particles Two-Phase Flow with Nearly Equal Density

This study deals with flow and pressure drop characteristics of liquid-solid two-phase flow, with small particles with almost the same density as the liquid, in a horizontal pipe. Effects of the particle size, particle concentration, and total flowrate on the pressure drop, particle distribution, and flow pattern were experimentally investigated for water-polystyrene particles flow using a visual video system and a pressure measuring system. The experimental results show that a peculiar pressure drop reduction appeared under the condition of uniform particle distribution. Theoretical results on the basis of a uniform two-phase flow model show that the pressure drop reduction occurs because the liquid velocity fluctuations are decreased owing to an interaction between the liquid and the particles.