Hydraulic transport of solid materials through pipe bends was investigated experimentally. Four kinds of 90° pipe bends of which the radii of curvature were 0, 12, 24 and 48cm, were made of polyacrylate pipe. The pressure drops were measured over sections of about 5 m, each including a pipe bend. The solid particles used in this experiment were glass beads (0.5-2.0mm diameter) and polystyrene particles (1.0mm diameter).
The behavior of particles in pipe bends was found to be very much complicated by the effect of gravitational and centrifugal forces and the secondary flow of fluid.
The results of the pressure-drop measurement were as follows, a) The horizontal pipe Bend : In the case of polystyrene particles, even though delivered particle concentration exceeded about 20%, the effect of particle concentration m^c on the pressure drop did not appear to be the same as in the case of a straight pipeline. On the other hand, in the case of glass particles the additional pressure drop, which was nearly constant regardless of flow rate, increased with increasing particle concentration except where R=0 and 12cm. Moreover, the additional pressure drop was correlated by the dimensionless term Um²/gR (ρ^s/ρ^w-1) and m^c. b) The vertical pipe bend : It was found from experiment that both polystyrene and glass particles showed additional pressure drop, which was nearly constant regardless of the flow rate, similar to the case of horizontal pipe bends.