Polymer additive mixing and turbulent drag reduction

Abstract

The turbulent drag reducing abilities of polyethylenoxide polymer additive is shown to depend not only upon the rate of mixing, but upon premixing procedures as well, of parent polymer solution being injected into the water flow at the inlet end of a rectangular experiment pipe via a rotating impeller mixer. Pressure drop measurements over a downstream measuring section along the pipe, correlated with visual observations on the presence of polymer strands in the flow by means of a schlieren arrangement indicate that forced mixing, so that all visible polymer strands dissappear, does not impair the drag reducing abilities of the additive until quite high rates of mixing.