Effect of drag-reducing polymers on annular gas–liquid flow in a horizontal pipe

Measurements of drag-reduction are presented for air and water flowing in a horizontal 0.0953 m pipe. The fluids had an annular configuration. The injection of polymer solution produced drag-reductions of about 48% with concentrations of only 10–15 ppm in the liquid. The effectiveness of the drag-reducing polymer is sensitive to the method of injection and the concentration of the polymer solution that is injected.