(85a) Downstream Development of Drag Reduction by Pipe Wall Injection of Concentrated Polyox into Water at Reynolds Numbers from 55000 to 140000

The downstream development of drag reduction following wall injection of concentrated polyethyleneoxide solutions into a turbulent water flow was studied by simultaneous pressure drop and flow visualization measurements at Reynolds numbers from 55000 to 140000 in a transparent acrylic test pipe of 15.7 mm ID and L/D = 430. The experiments partially modeled drag reduction in the Trans-Alaska Pipeline System, by roughly matching (i) the pipe friction velocity uô ~ 0.15 m/s, (ii) the backbone chain links Nbb ~ 0.5x106 and downstream concentrations Cline ~ 5 wppm of the polymer additive and (iii) the wall injection of concentrated polymer through equi-spaced circumferential ports at friction-normalized injection velocities Vinj+ ~ 1