Abstract
The drag reduction effect was experimented in turbulent flows through a pipe of the diameter 3.17mm for surfactant solutions. As water, Newtonian fluids is not shown the drag reduction. In surfactant solution, dilute Ethoquad aqueous solution give similar results in the case of Newtonian fluids, and Ethoquad aqueous solution adding NaSal have the tendency of large drag reduction. For the solutions which are shown the drag reduction, in low frequancy region, the power spectrum of these are higher than that of water.
