Universal drag reduction characteristics of saline water-soluble poly(ethylene oxide) in a rotating disk apparatus

Polymer-induced turbulent drag reduction in a rotating disk apparatus was i nvestigated using nonionic poly(ethylene oxide) (PEO) in a synthetic saline solution with novel application to ocean thermal energy conversion technol ogy. A maximum total (skin friction plus form) drag reduction of 30% was ob tained with 50 wppm of PEO with molecular weight 5.0 x 10(6). The concentra tion dependence of the percentage drag reduction for the PEO/saline solutio n system is found to fit Virk's empirical correlation, and a universal corr elation for various molecular weights and Reynolds numbers is also presente d. Furthermore, hydrodynamic volume fraction was introduced to correlate dr ag reduction efficiency with molecular parameters in this PEO/saline soluti on system.