Wasserlösliche hochpolymere als strömungsbeschleuniger

Interthal, W.

doi:10.1002/apmc.1984.051230118

Cited by 8 publications

(3 citation statements)

References 68 publications

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“…For the tests with the 3 mm pipe a turbulence rheometer was available which was built with reference to [13] and will be described elsewhere [14].…”

Section: Test Devices and Methods Of Measurementmentioning

confidence: 99%

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Drag reduction experiments with very large pipes

Interthal¹,

Wilski²

1985

Colloid & Polymer Sci

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Various substances have been tested in the laboratory for their suitability as flow enhancers in aqueous solutions. The following maximum drag reductions (%) were obtained with pipes of 14 mm diameter and a Reynolds number of 10s: Na-carboxy methylcellulose (32), hydroxyethyl cellulose (42), cetyltrimethylammonium chloride/ cr-naphthol (74; Re = 104), polyethylene oxide (76), K-polyphosphate/Na-pyrophosphate (77), polyacrylamide (80). The tested, partially hydrolysed polyacrylamide which was produced by a special process was found to be not only extremely effective and highly resistant to shear degradation but also unaffected by the salt content, the temperature and the water spoilage. Experiments were therefore made with this material on an industrial scale, that is to say with pipes up to 750 mm in diameter and 3200 m in length. Whilst in the laboratory (pipes up to 14 mm in diameter) drag reductions were measured according to the Virk asymptote, the results obtained with large pipe diameters were lower. At diameters ranging from 300 to 750 mm a maximum drag reduction of 65 % (at a concentration of 30 ppm PAAM and a constant wall shear stress of 50 Pa) has been obtained independently of the diameter.

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“…For the tests with the 3 mm pipe a turbulence rheometer was available which was built with reference to [13] and will be described elsewhere [14].…”

Section: Test Devices and Methods Of Measurementmentioning

confidence: 99%

“…In the alkaline range on the other hand the carboxyl groups are dissociated; the mutual repulsion of the anionic charges brings about an opening up of the coil and thus a stronger interaction with the solvent. The mechanism and the interrelated theoretical notions have been reported elsewhere [14,21,22].…”

Section: Dependence On Temperaturementioning

confidence: 97%

Drag reduction experiments with very large pipes

Interthal¹,

Wilski²

1985

Colloid & Polymer Sci

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“…The discovery made by these two authors has stimulated a large number of investigations, most of which have been performed using high molecular polymers as additives [3,4]. In contrast, drag reduction by surfactants has so far been much less thoroughly investigated.…”

Section: Introductionmentioning

confidence: 97%

Surfactant systems for drag reduction: Physico-chemical properties and rheological behaviour

1986

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The first part of the work presents an overview of the physical chemistry of surfactants which in aqueous solutions reduce the frictional loss in turbulent pipe flow. It is shown that these surfactants form rodlike micelles above a characteristic concentraion c t. The experimental evidence for rodlike micelles are reviewed and the prerequisites that the surfactant system must fulfill in order to form rodlike micelles are given. It is demonstrated by electrical conductivity measurements that the critical concentration for the formation of spherical micelles shows little temperature dependence, whereas ct increases very rapidly with temperature. The length of the rodlike micelles, as determined by electric birefringence, decreases with rising temperature and increases with rising surfactant concentration. The dynamic processes in these micellar systems at rest and the influence of additives such as electrolytes and short chain alcohols are discussed.In the second part, the rheological behaviour of these surfactant solutions under laminar and turbulent flow conditions are investigated. Viscosity measurements in laminar pipe and Couette flow show the build-up of a shear induced viscoelastic state, SIS, from normal Newtonian fluid flow. A complete alignment of the rodlike micelles in the flow direction in the SIS was verified by flow birefringence. In turbulent pipe flow, drag reduction occurs in these surfactant systems as soon as rodlike micelles are present in the solution. The extent and type of drag reduction, i.e. the shape of the friction factor versus Reynolds number curve, depends directly on the size, number and surface charge of the rodlike micelles. The friction factor curve of each surfactant investigated changes in the same characteristic way as a function of temperature. For each surfactant, independent of concentration, an upper absolute temperature limit, TL, for drag reduction exists which is caused by the micellar dynamics. T L is influenced by the hydrophobic chain length and the counter-ion of the surfactant system. A first attempt is made to explain the drag reduction of surfactants by combining the results of these rheological measurements with the physico-chemical properties of the micellar systems.

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Lösungen und Gele

2002

Makromoleküle

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Wasserlösliche hochpolymere als strömungsbeschleuniger

Cited by 8 publications

References 68 publications

Drag reduction experiments with very large pipes

Drag reduction experiments with very large pipes

Surfactant systems for drag reduction: Physico-chemical properties and rheological behaviour

Lösungen und Gele

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