EFFECT OF PIPE DIAMETER ON TURBULENT DRAG REDUCTION

The present work is an attempt for gaining some experimental data to investigate the effect of pipe diameter and roughness on drag reduction properties. Experiments were carried out in galvanized steel pipes whose nominal diameters were 12.7, 19.05, 31.75 and 50.8 mm (0.5, 0.75, 1.25 and 2 inches) respectively and in smooth polyvinyl chloride (PVC) pipe with 19.05 mm diameter. Two water soluble additives were selected for the study.These were polyethylene oxide (PEO) as a flexible long chain polymer with a molecular weight of 1*10₇  g/mol and sodium stearate (SS) as anionic detergent.The effect of additive concentration, up to 100 ppm for PEO and up to 400 ppm for SS, bulk velocity, addition of pipe diameter and type were studied in details. It was observed generally, that a gradual increase of percent drag
reduction with increasing the pipe diameter, bulk velocity and additive concentrations. The drag reduction observed for sodium stearate detergent in tap water is much lower than for the flexible, long chain polyethylene oxide polymer, in whole considered flowing conditions. Those, a maximum drag reduction of 36% and 13.6% has been achieved when 100 ppm PEO and 400 ppm SS where added respectively at Reynolds number equal 41794.14 in 50.8 mm pipe diameter.