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Experimental correlation for pipe flow drag reduction using relaxation time of linear flexible polymers in a dilute solution
Author(s) -
Zhang Xin,
Duan Xili,
Muzychka Yuri,
Wang Zongming
Publication year - 2020
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23649
Subject(s) - drag , weissenberg number , reynolds number , dimensionless quantity , turbulence , mechanics , flow (mathematics) , parasitic drag , materials science , relaxation (psychology) , drag coefficient , polymer , pipe flow , reduction (mathematics) , thermodynamics , mathematics , physics , composite material , geometry , psychology , social psychology
In this study, we investigate the drag reduction property of a linear flexible polymer, PEO (polyethylene oxide) in a fully turbulent pipe flow. The aim of this study is to develop a correlation to predict the drag reduction using the Weissenberg number, a dimensionless number related to the relaxation time of the polymer and the polymer concentration in dilute solutions. The physical meaning of the relaxation time of polymers and overlap concentration between the dilute and semi‐dilute polymer solution are clarified. A higher polymer concentration, Reynolds number, and Weissenberg number lead to an increasing drag reduction. A semi‐empirical correlation to predict the drag reduction with two dimensionless variables mentioned above is established and can predict the experimental data in this work and other previous works well. Previous correlations that use Reynolds number often require high flow velocity or large pipes in the experimental setup to predict drag reduction in large‐scale industrial applications, which involves extra cost and potential safety issues. The current new correlation method uses relatively low velocities to avoid the problems mentioned above.