Drag Reduction And Degradation Of Dilute Polymer Solutions In Turbulent Pipe Flows
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Drag Reduction And Degradation Of Dilute Polymer Solutions In Turbulent Pipe Flows
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Author : T. T. Huang
language : en
Publisher:
Release Date : 1971
Drag Reduction And Degradation Of Dilute Polymer Solutions In Turbulent Pipe Flows written by T. T. Huang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with Drag (Aerodynamics) categories.
Drag reduction caused by dilute polyethylene oxide (POLYOX WSR-301) and anionic charged polyacrylimide (MAGNIFLOC 835A) polymer solutions was studied experimentally in 1.918- and 0.455-cm ID smooth pipes. The POLYOX solutions tested are superior in drag reduction but inferior in shear-degradation resistance compared to the MAGNIFLOC solutions at corresponding concentrations. A three-layer mean velocity profile model appears to be more consistent with current and other data than a traditional two-layer model. The onset of measured drag reduction depends upon solution concentration and is seriously affected by shear degradation. (Author).
Turbulent Flow Drag Reduction And Degradation With Dilute Polymer Solutions
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Author : Robert W. Paterson
language : en
Publisher:
Release Date : 1969
Turbulent Flow Drag Reduction And Degradation With Dilute Polymer Solutions written by Robert W. Paterson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1969 with categories.
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).
Drag Reduction Of Turbulent Flows By Additives
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Author : A. Gyr
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-03-09
Drag Reduction Of Turbulent Flows By Additives written by A. Gyr and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-03-09 with Technology & Engineering categories.
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.
Drag Reduction Degradation Of Dilute Polymer Solutions In Turbulent Tube Flow
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Author : Nicholas D. Sylvester
language : en
Publisher:
Release Date : 1971
Drag Reduction Degradation Of Dilute Polymer Solutions In Turbulent Tube Flow written by Nicholas D. Sylvester and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with categories.
Drag reduction degradation characteristics of Separan AP30 are reported. A recycle tube flow experiment was used to investigate this property of drag reducing polymer solutions. Experimental pressure gradient and flow rate measurements were made as a function of time. From this data, friction factor- time plots on log-log coordinates were constructed, all of which exhibited three distinct regions which are discussed. Correlations are presented relating the process time in which maximum drag reduction exists, and the process time in which significant drag reduction exists, to the polymeric and system flow variables.
Analytical And Experimental Study Of Turbulent Flow Drag Reduction And Degradation With Polymer Additives
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Author : Xin Zhang
language : en
Publisher:
Release Date : 2020
Analytical And Experimental Study Of Turbulent Flow Drag Reduction And Degradation With Polymer Additives written by Xin Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Flow friction reduction by polymers is widely applied in the oil and gas industry for flow enhancement or to save pumping energy. The huge benefit of this technology has attracted many researchers to investigate the phenomenon for 70 years, but its mechanism is still not clear. The objective of this thesis is to investigate flow drag reduction with polymer additives, develop predictive models for flow drag reduction and its degradation, and provide new insights into the drag reduction and degradation mechanism. The thesis starts with a semi-analytical solution for the drag reduction with polymer additives in a turbulent pipe flow. Based on the FENE-P model, the solution assumes complete laminarization and predicts the upper limitation of drag reduction in pipe flows. A new predictive model for this upper limit is developed considering viscosity ratios and the Weissenberg number - a dimensionless number related to the relaxation time of polymers. Next, a flow loop is designed and built for the experimental study of pipe flow drag reduction by polymers. Using a linear flexible polymer - polyethylene oxide (PEO) - in water, a series of turbulent flow experiments are conducted. Based on Zimm's theory and the experimental data, a correlation is developed for the drag reduction prediction from the Weissenberg number and polymer concentration in the flow. This correlation is thoroughly validated with data from the experiments and previous studies as well. To investigate the degradation of drag reduction with polymer additives, a rotational turbulent flow is first studied with a double-gap rheometer. Based on Brostow's assumption, i.e., the degradation rate of drag reduction is the same as that of the molecular weight decrease, a correlation of the degradation of drag reduction is established, along with the proposal of a new theory that the degradation is a first-order chemical reaction based on the polymer chain scission. Then, the accuracy of the Brostow's assumption is examined, and extensive experimental data indicate that it is not correct in many cases. The degradation of drag reduction with polymer additives is further analyzed from a molecular perspective. It is found that the issue with Brostow's theory is mainly because it does not consider the existence of polymer aggregates in the flow. Experimental results show that the molecular weight of the degraded polymer in the dilute solution becomes lower and the molecular weight distribution becomes narrower. An improved mechanism of drag reduction degradation considering polymer aggregate is proposed - the turbulent flow causes the chain scission of the aggregate and the degraded aggregate loses its drag-reducing ability. Finally, the mechanism of drag reduction and degradation is examined from the chemical thermodynamics and kinetics. The drag reduction phenomenon by linear flexible polymers is explained as a non-spontaneous irreversible flow-induced conformational-phase-change process that incorporates both free polymers and aggregates. The entire non-equilibrium process is due to the chain scission of polymers. This theory is shown to agree with drag reduction experimental results from a macroscopic view and polymer behaviours from microscopic views. The experimental data, predictive models, and theories developed in this thesis provide useful new insights into the design of flow drag reduction techniques and further research on this important physical phenomenon.
Drag Reduction By Dilute Polymer Solutions In Turbulent Flow
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Author : Ralph C. Little
language : en
Publisher:
Release Date : 1967
Drag Reduction By Dilute Polymer Solutions In Turbulent Flow written by Ralph C. Little and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1967 with categories.
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).
The Toms Phenomenon
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Author : Preetinder Singh Virk
language : en
Publisher:
Release Date : 1966
The Toms Phenomenon written by Preetinder Singh Virk and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1966 with Pipe categories.
Drag reduction caused by dilute, distilled water solutions of five polyethylene oxides, molecular weights from 80,000 to 6,000,000, in turbulent pipe flow was studied experimentally in 0.292 cm and 3.21 cm ID pipes. It was found that: The onset of drag reduction occurs at a well-defined wall shear stress related to the random coiling effective diameter of the polymer by the Onset Hypothesis. Laminar to turbulent transition is not, in general, delayed. The extent of drag reduction induced by a homologous series of polymers in a given pipe is a universal function of concentration, uniquely related to flow rate and molecular weight. The maximum drag reduction possible is limited by a universal asymptote that is independent of polymer and pipe diameter. In polymer solution, both the stagnation pressure attained with Pitot tubes and the heat transfer from cylinders in cross flow are drastically different from Newtonian; in general, both are lower. (Author).
Polymer Chain Scission In Extensional And Turbulent Flows And Implications For Friction Drag Technologies
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Author : Siva A. Vanapalli
language : en
Publisher:
Release Date : 2006
Polymer Chain Scission In Extensional And Turbulent Flows And Implications For Friction Drag Technologies written by Siva A. Vanapalli and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Pipe Flow Of Dilute Polymer Solutions
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Author : Chien-Bang Wang
language : en
Publisher:
Release Date : 1969
Pipe Flow Of Dilute Polymer Solutions written by Chien-Bang Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1969 with Fluid dynamics categories.
Drag Reduction In Flow Of Dilute Polymer Solutions
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Author : James Henry Hand
language : en
Publisher:
Release Date : 1971
Drag Reduction In Flow Of Dilute Polymer Solutions written by James Henry Hand and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with categories.