Abstract
High shear drag reduction due to additives was experimentally investigated in a turbulent tube flow. The cationic surfactant solution indicated the drag reduction of 50 % at the shear stress of 100 Pa for the combination with the counter ion of. ten times higher molar concentration. The dispersions of nanotubes and potassium titanate whiskers canceled the frictional increase due to the viscosity increase, but the drag reduction was not obtained compared with the friction of dispersing water. The investigation for the optimized flow condition is still necessary to achieve more effective drag reduction.
