Flow Pattern and Frictional Losses in Pulsating Pipe Flow : Part 4, General Representation of Turbulent Frictional Losses

概要

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Friction factors in a pulsating turbulent pipe flow are estimated from the flow pattern diagrams shown in a previous paper and the effect of frequency and time-averaged Reynolds number Re+a on the frictional losses is verified with experimental data. The instantaneous friction factor λ_u,ta may be generally expressed as functions of ω'/Re^3/4_<ta> , where ω' is a dimensionless frequency. Here, λ/u(t) is almost equal to the quasi-steady friction factor λ_g in the quasi-steady region, but in the intermediate and the inertia dominant regions, λ_u, ta increases with an increase in both ω'/Re^3/4_<ta> and velocity amplitude ratio A_1. In addition, more adequate values indicating the limits between the above mentioned three regions are proposed.
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