An Estimation of the Wall Friction in Vertical Air-Solid Two-Phase Flow

Abstract

The coefficient of friction introduced as the constant depending on the combination of solid particle and pipe material is considered. This investigation provides that the coefficient of friction is equal to the sum of both the coefficient of pressure drop caused by the friction and the collision of particles at the pipe wall as well as that caused by the mutual collision of particles in the flow. Using the experimental results of the pressure drop in the steady region of the flow over a wide range of solid properties and pipe diameters, the value of the wall friction has been obtained for each combination of solid and pipe material.