Drag reduction in turbulent flow by polymer additive with longitudinal excitation

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Drag reduction in turbulent flow by polymer additive with longitudinal excitation


Author: Mo, Mun Tong
Title: Drag reduction in turbulent flow by polymer additive with longitudinal excitation
Degree: M.Sc.
Year: 1995
Subject: Frictional resistance (Hydrodynamics)
Polymer solutions
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Mechanical Engineering
Multi-disciplinary Studies
Pages: viii, 87 leaves : ill. ; 30 cm
Language: English
OneSearch: https://www.lib.polyu.edu.hk/bib/b1219800
URI: http://theses.lib.polyu.edu.hk/handle/200/2924
Abstract: It has been known for many year that solutions of high polymers can be irreversibly reduced by ultrasonic irradiation or high speed stirring. Experimental studies of drag reduction and polymer degradation in turbulent flow with dilute water solution of a brass pipe under the forced excitation at the end of the pipe are described. The fundamental natural frequency of the testing section is employed to intensify the excitation effect. Two sets of experiments (1) no excitation; (2) with excitation at four different Reynolds Numbers are undertaken to investigate the influence of excitation. The trend of the friction factor and percentage of drag reduction are interpreted and justified in term of number of passes and time. Moreover, the mechanical degradation of the polymer under excitation is also concerned, and the obtained results are compared with the un-excited flow. A formula of the relationship between the required time for an excited flow to catch up with the gross flow and its Reynolds No. is developed. It therefore seems likely that the excitation of the pipe can enlarge the rate of polymer degradation.

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