抄録
A system for feedback control of pulsating pipe flow has been experimentally examined for friction-drag reduction in a turbulent pipe flow.The rotating speed of a centrifugal pump was changed for generating the pulsating flow.A magnetic flow meter and a pressure gauge are employed for measurement of normalized pressure gradient.The rotating speed is gradually increased while the normalize pressure gradient is over a threshold value 0.018 for re-laminarization.It is found that the wall shear stress is decreased by about 5.9% when the cycle-averaged friction Reynolds number based on the friction velocity,the radius and the kinematic viscosity was set to be 177.
