Analytical And Experimental Study Of Turbulent Flow Drag Reduction And Degradation With Polymer Additives
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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.
Turbulent Drag Reduction By Surfactant Additives
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Author : Feng-Chen Li
language : en
Publisher: John Wiley & Sons
Release Date : 2012-01-10
Turbulent Drag Reduction By Surfactant Additives written by Feng-Chen Li and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-01-10 with Science categories.
Turbulent drag reduction by additives has long been a hot research topic. This phenomenon is inherently associated with multifold expertise. Solutions of drag-reducing additives are usually viscoelastic fluids having complicated rheological properties. Exploring the characteristics of drag-reduced turbulent flows calls for uniquely designed experimental and numerical simulation techniques and elaborate theoretical considerations. Pertinently understanding the turbulent drag reduction mechanism necessities mastering the fundamentals of turbulence and establishing a proper relationship between turbulence and the rheological properties induced by additives. Promoting the applications of the drag reduction phenomenon requires the knowledge from different fields such as chemical engineering, mechanical engineering, municipal engineering, and so on. This book gives a thorough elucidation of the turbulence characteristics and rheological behaviors, theories, special techniques and application issues for drag-reducing flows by surfactant additives based on the state-of-the-art of scientific research results through the latest experimental studies, numerical simulations and theoretical analyses. Covers turbulent drag reduction, heat transfer reduction, complex rheology and the real-world applications of drag reduction Introduces advanced testing techniques, such as PIV, LDA, and their applications in current experiments, illustrated with multiple diagrams and equations Real-world examples of the topic’s increasingly important industrial applications enable readers to implement cost- and energy-saving measures Explains the tools before presenting the research results, to give readers coverage of the subject from both theoretical and experimental viewpoints Consolidates interdisciplinary information on turbulent drag reduction by additives Turbulent Drag Reduction by Surfactant Additives is geared for researchers, graduate students, and engineers in the fields of Fluid Mechanics, Mechanical Engineering, Turbulence, Chemical Engineering, Municipal Engineering. Researchers and practitioners involved in the fields of Flow Control, Chemistry, Computational Fluid Dynamics, Experimental Fluid Dynamics, and Rheology will also find this book to be a much-needed reference on the topic.
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.
An Experimental Study Of Turbulent Diffusion Of Drag Reducing Polymer Additives
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Author : R. R. Walters
language : en
Publisher:
Release Date : 1970
An Experimental Study Of Turbulent Diffusion Of Drag Reducing Polymer Additives written by R. R. Walters and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1970 with Boundary layer control categories.
Experimental Investagation Of Drag Reduction Effects Of Polymer Additives On Turbulent Pipe Flow
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Author :
language : en
Publisher:
Release Date : 2005
Experimental Investagation Of Drag Reduction Effects Of Polymer Additives On Turbulent Pipe Flow written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Since the discovery of the drag reduction effects of even small amount of macromolecules in solutions in turbulent pipe flows, there have been many experimental and theoretical studies in order to understand mechanisms behind this phenomenon. Theories have been proposed based on the observations on the change in the characteristics of the turbulent flow near the pipe wall where friction of the momentum transfer between the flow and the conduit takes place. In this study drag reduction in fully developed turbulent pipe flow with four concentrations (200 to 500 wppm) of low molecular weight Sodium Carboxymethylcellulose (CMC) in aqueous solutions was investigated experimentally. Drag reduction was determined by pressure drop measurements. In order to observe the impact of the presence of CMC on the flow, Ultrasound Doppler Velocimetry (UDV) was employed to monitor the instantaneous velocity distributions. UDV is a non-invasive technique allowing one to obtain quick velocity profiles. Experimental measurements were used to calculate Fanning friction factor and radial distributions of the axial time-averaged velocity, velocity fluctuation (turbulent intensity) and eddy viscosity. The drag reduction level was determined through the Fanning friction factor versus Reynolds number data. Velocity data could be obtained as close as 3 mm to the wall by UDV. Two impacts of increasing CMC concentration on the flow field, hence pressure drop, were observed. The first effect was the decrease of the mean velocity gradient especially near the wall with increasing polymer amount which in turn gave rise to lower friction factor or pressure drop. In addition smaller eddy viscosities were obtained in the flow. The second impact of the polymer addition was on the velocity fluctuation or turbulent intensity variation along the radial distribution. An increasing trend in turbulence intensity in the turbulent core with polymer addition was observed. This was in agreement with the earlier st.
Drag Reduction Of Complex Mixtures
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Author : Keizo Watanabe
language : en
Publisher: Academic Press
Release Date : 2018-06-15
Drag Reduction Of Complex Mixtures written by Keizo Watanabe and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-15 with Technology & Engineering categories.
Drag Reduction of Complex Mixtures discusses the concept of drag reduction phenomena in complex mixtures in internal and external flows that are shown experimentally by dividing flow patterns into three categories. The book is intended to support further experiments or analysis in drag reduction. As accurately modeling flow behavior with drag reduction is always complex, and since drag reducing additives or solid particles are mixed in fluids, this book covers these complex phenomena in a concise, but comprehensive manner. Comprehensively addresses a range of drag reduction themes involving different kinds of complex mixtures Provides data to support further experimentation and computer modeling of drag in complex flow Includes an introduction to the nature and characteristics of different kinds of complex mixtures
Viscous Drag Reduction
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Author : C. Sinclair Wells
language : en
Publisher: Springer
Release Date : 2013-12-20
Viscous Drag Reduction written by C. Sinclair Wells and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-12-20 with Technology & Engineering categories.
Drag Reduction In Fluid Flows
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Author : Robert H. J. Sellin
language : en
Publisher:
Release Date : 1989
Drag Reduction In Fluid Flows written by Robert H. J. Sellin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Boundary layer control categories.
Turbulent Flow Drag Reduction By Dilute Poly Ethylene Oxide Solutions In Capillary Tubes
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Author : Ira Michael Felsen
language : en
Publisher:
Release Date : 1971
Turbulent Flow Drag Reduction By Dilute Poly Ethylene Oxide Solutions In Capillary Tubes written by Ira Michael Felsen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with Fluid dynamics categories.
The study was initiated to investigate turbulent flow drag-reduction by dilute poly(ethylene oxide) solutions in capillary tubes and thereby elucidate the mechanism of drag-reduction through interpretation of the experimental results. Flow through capillary tubes was chosen as a means to (1) obtain a large ratio of solid surface area to fluid volume, and (2) obtain high shear stresses at low Reynolds numbers. This allowed investigation of surface effects and polymer degradation as a function of a number of variables which are known to influence drag-reduction. (Author).
A Theoretical And Experimental Study Of Turbulent Drag Reduction
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Author : Panagiotis Katsibas
language : en
Publisher:
Release Date : 1973
A Theoretical And Experimental Study Of Turbulent Drag Reduction written by Panagiotis Katsibas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with Drag (Aerodynamics) categories.