The frictional dragreducing characteristics of Shell PEP-4 and Conoco CDR polymer-hexane solutions in turbulent smooth tube flow were investigated. The effects of flow time, polymer concentration, Reynolds number and tube diameter on drag reduction and degradation were evaluated. The Conoco polymer was found to be the superior drag reducer. Independent of polymer, higher shear stresses (smaller tube diameters or higher Reynolds numbers) resulted in higher maximum drag reductions up to a critical shear stress, after which the polymer effectiveness decreased. Increased concentrations gave increased...
The frictional dragreducing characteristics of Shell PEP-4 and Conoco CDR polymer-hexane solutions in turbulent smooth tube flow were investigated. The effects of flow time, polymer concentration, Reynolds number and tube diameter on drag reduction and degradation were evaluated. The Conoco polymer was found to be the superior drag reducer. Independent of polymer, higher shear stresses (smaller tube diameters or higher Reynolds numbers) resulted in higher maximum drag reductions up to a critical shear stress, after which the polymer effectiveness decreased. Increased concentrations gave increased drag reductions approaching Virk’s maximum drag reduction asymptote. Three flow regimes were established: an asymptotic region of maximum drag reduction without significant degradation at early times, an intermediate region with varying degradation, and a final asymptotic region approaching Newtonian solvent behavior at long times. Higher degradation rates were observed for lower concentrations and higher shear stresses.