Measurements of wall shear stress and its drag reduction in swirling flows through a curved pipe

摘要

The effect of the injection of swirling motion into turbulent flows through a curved pipe is studied experimentally by measuring distributions of wall shear stress and three-component velocities. The high and low region of wall shear stress corresponds to the fast slow region of primary flow near the wall which is governed by the vortical structure. The flow friction of the average wall shear reduces when the injected swirl is weak.