A Study on Anomalous Turbulent FIows of Non-Newtonian Fluids : 2nd Report, Transitional Region from Laminar to Turbulent Flow

Abstract

Transition from laminar to turbulent pipe flows of dilute polymer solutions is investigated experimentally. 0.5∼120 wppm waster solutions of PEO 18 are used and the following results are obtained on the pipes 0.256 cm and 0.132 cm in diameter. (1) Before transition there is a flow region where the friction factor λ departs gradually upward from the line λ=64/R_e. This region begins at a lower than the critical Reynolds number of Newtonian fluid (≈2300). (2) There appear wavy surfaces or windings on the jets in this flow region, and a change of the jet appearance corresponds to that of the friction factor approximately. (3) It is made clear that wavy surfaces or windings occur by fluctuations in a pipe flow and the fluctuations are different from those of transition of water.