Abstract
It is known that a surfactant solution with appropriate counter ion induces the structure of fiber-like micelles in a shear flow field. When the structure is induced, the drag of the pipe flow is reduced. Based on the fact, we presumed that structure of agglomerated particles in a particle suspension also causes the same effect. Thus, we attempted to reduce the pressure drop of the suspension flow by adding a polymer flocculant. In this study, we investigated the change of the pressure drop of the pipe flow with the flocculant concentration. The change of the drag was evaluated by the drag reduction rate defined by the ratio of the difference of the friction factor between water flow and suspension flow to the friction factor of water flow.
It was found that the suspension with polymer flocculant caused the drag reduction under the conditions of particle concentration 1 and 10vol%. In the same flocculant concentration, the water solution of the flocculant (=without particles) also caused the drag reduction. However, the drag reduction rate of the solution was less than that of the suspension with flocculant under certain conditions. The fact shows that the particle enhances the drag reduction.
From the observation of the flocculate in a stationary fluid, it was found that independent agglomerations were formed when the drag reduction was enhanced. The fact shows that the drag reduction is attributed by agglomerated particles. It leads to an expectation that the drag reduction can be achieved in any other solid-liquid suspension if proper agglomeration is formed.
