Flow Pattern and Frictional Losses in Pulsating Pipe Flow : Part 7 Wall Shear Stress in a Turbulent Flow

Abstract

Flow patterns in a pulsating turbulent pipe flow are classified into three types, i.e., the quasi-steady, the intermediate, and the inertia dominant regions with respect to dimensionless frequency ω' and time-averaged Reynolds number Reta. Although the behaviour of frictional losses in the quasi-steady and the intermediate regions is being made clear experimentally, very little is known about them in the inertia dominant region. Assuming that if ω' is large enough, wall shear stress τω becomes similar to that in a pulsating laminar pipe flow, two approximate representations for τω are proposed. The characteristic parameters describing the flow pattern and the frictional losses estimated from these representations are compared with experimental results and the applicability of these representations is examined.