Turbulent Flow Drag Reduction with Dilute Polymer Solutions PDF Download
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Author: Robert William Paterson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Robert William Paterson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Ralph C. Little
Publisher:
ISBN:
Category :
Languages : en
Pages : 25
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The mechanism by which water-soluble polymers reduce hydrodynamic drag on solid surfaces was investigated by measurements of flow birefringence and of turbulent flow in pipes. Flow birefringence and flow field orientation of Polyox polymers in the molecular weight range from 200,000 to 6,000,000 showed that Polyox macromolecules continue to deform with increasing velocity gradient even after alignment with the flow field (at gradients in excess of 2000/sec). All solutions used were found to be Newtonian, with the exception of the AcrysolA-5 solutions. The flow data for Polyox solutions in a Pyrex pipe were examined in terms of Meyer's fluid property parameter and Elata's relaxation time hypothesis for the initiation of drag reduction. It was found that drag reduction in the Pyrex pipe was initiated at a value of the order of one-fifth that predicted by Elata's theory. Moreover, added salt (the solution being 0.3 molar in K2SO4) had no effect on the flow of Polyox Coagulant solutions even though the intrinsic viscosity (upon which Rouse relaxation times depend) was cut to slightly more than one-third of its value in the pure solvent. The unusually high values of Meyer's fluid property parameter observed at low concentrations suggests that adsorption on the Pyrex pipe walls may be playing a role in drag reduction. (Author).
Author: Robert W. Paterson
Publisher:
ISBN:
Category :
Languages : en
Pages : 197
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The purpose of the study was to attempt to find an explanation for the phenomenon first reported by Toms in 1948 in which the addition of a few grams of a long chain polymer to a million cubic centimeters of a Newtonian solvent caused a large decrease in the turbulent pipe flow pressure drop while causing only a small increase in the laminar flow viscosity. This phenomenon, which has been observed to occur for a number of different polymers and solvents, is commonly referred to as 'drag reduction with dilute polymer solutions' or 'the Toms phenomenon'. (Author).
Author: A. Gyr
Publisher: Springer Science & Business Media
ISBN: 9401712956
Category : Technology & Engineering
Languages : en
Pages : 243
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Drag Reduction of Turbulent Flows by Additives is the first treatment of the subject in book form. The treatment is extremely broad, ranging from physicochemical to hydromechanical aspects. The book shows how fibres, polymer molecules or surfactants at very dilute concentrations can reduce the drag of turbulent flow, leading to energy savings. The dilute solutions are considered in terms of the physical chemistry and rheology, and the properties of turbulent flows are presented in sufficient detail to explain the various interaction mechanisms. Audience: Those active in fundamental research on turbulence and those seeking to apply the effects described. Fluid mechanical engineers, rheologists, those interested in energy saving methods, or in any other application in which the flow rate in turbulent flow should be increased.
Author: James Henry Hand
Publisher:
ISBN:
Category :
Languages : en
Pages : 680
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Author: Hyunkook Shin
Publisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 590
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The object of this thesis was to investigate the drag reduction phenomenon in turbulent flow caused by random coiling macromolecules in 'dilute' solution. In particular, this thesis was concerned with the relationship of drag (or its reduction) to the size of the coils and their concentration, of two kinds of polymers differing significantly in chain flexibility: polyethylene oxide (PEO), the more flexible, and polyisobutylene (PIB), the less flexible. It was found that, within any given homologous polymer series, the ability of macromolecules to reduce drag improved drastically with increasing molecular weight. That is, the concentration of polymers in solution either in the absolute weight fraction or in the effective volume fraction required to yield a given percent drag reduction decreased rapidly with increasing molecular weight. It was further found that there always existed an optimum concentration for any given polymer system at which the observed drag reduction reached a maximum.
Author:
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ISBN:
Category : Dissertations, Academic
Languages : en
Pages :
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Author: C. Sinclair Wells
Publisher: Springer
ISBN: 1489955798
Category : Technology & Engineering
Languages : en
Pages : 497
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Author: T. T. Huang
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 35
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Velocity similarity laws, based on a four-layer, mean-velocity-profile model are deduced for turbulent boundary layers with dilute polymer solutions by means of pipe-flow experiments. Measured drag reduction is studied in three domains: undersaturated, optimal, and oversaturated. Drag reduction increases with increasing concentration in the undersaturated domain where the four-layer profile exists in the boundary layer. The boundary between the two domains gives optimal drag reduction; it is determined by the polymer type and concentration and by a Reynolds number based on shear velocity and boundary-layer thickness. The effects of solvent temperature, pipe diameter, polymer type and concentration, and wall shear stress on the measured drag reduction have been investigated. (Modified author abstract).
Author: Hsun-fu David Chang
Publisher:
ISBN:
Category : Polymerization
Languages : en
Pages : 224
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