Download or read book Drag Reduction by Polymer Addition written by Marten T. Landahl and published by . This book was released on 1972 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Special attention is paid to the changes in turbulence structure brought about by polymer additives, and an effort is made to understand these in the light of recent advances in the study of shear flow turbulence in ordinary fluids. Also a simplified theoretical model of shear flow wall turbulence is presented, with the aid of which an exploratory study of the influence of some non-Newtonian fluid properties is carried out. A particularly intriguing feature is the remarkable effectiveness of extremely high-molecular-weight polymers by which only a few parts per million of weight of solvent are sufficient in some cases to lead to drag reductions of 50 per cent or more. (Modified author abstract).

Download or read book Turbulent Drag Reduction by Addition of Polymer to Water written by Richard Yu Chu Chung and published by . This book was released on 1966 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigating the Degradation Resistance Improvement of the Polymeric Drag Reduction written by Esmail Abdullah Mohammed Basheer and published by . This book was released on 2013 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important practical aspect in the application and study of drag reduction by polymer additives is the degradation of the polymer, for instance due to intense shearing, especially in circulatory flow systems. Such degradation leads to a marked loss of the drag-reducing capability of the polymer. Polymers-Surfactant complex efficacy in reducing the drag and improving the degradation resistance is a new subject in drag reduction research. Turbulent drag reduction (DR) efficacy of ionic Sodium Polystyrene Sulfonate (NaPSS) and sodium Alkylbenzene sulfonate, complexes systems regarding polymer-surfactant interaction was examined under a turbulent flow in a rotating disk apparatus, in which the DR efficacy indicates how the torque is being reduced with a tiny amount of additives under a turbulent flow at a fixed rotational speed. It was found that the addition of the surfactant to the ionic increased the polymer chain dimensions via a conformational structural change, thus enhancing the DR efficacy. Polymer-surfactant system also shows that there exists a critical polymer concentration at which the drag reduction becomes a maximum, and then above the critical concentration, the DR efficacy decreases more rapidly than that of pure polymeric systems. On the other hand, it was found that the addition of the surfactant to the ionic polymer enhance its ability to resist the degradation caused by the high shear stress in the eddy flow. The addition of sodium Alkylbenzene sulfonate to the ionic polymer was found to have higher improvement than the addition of DDAB in degradation resistance. The DR and degradation resistance efficacy induced by the polymer-surfactant mixture is found to be obvious higher than of pure polymer. In addition, the maximum of DR efficacy versus polymer concentration occurred at 700 ppm.

Download or read book The Influence of Drag Reducing Polymer Additives on Surface Pressure Fluctuations on Rough Surfaces written by John M. Killen and published by . This book was released on 1971 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental measurements were made to determine the effect of drag reducing polymer additives on the surface pressure fluctuations on smooth and rough surfaces in relative motion with water. Changes in surface pressure fluctuation intensity, caused either by the addition of drag reducing polymer or by changes in surface roughness, or both, were found to correlate with changes in surface shear. (Author).

Download or read book Turbulent Drag Reduction by Polymers Surfactants and Their Mixtures in Pipeline Flow written by Ali Asghar Mohsenipour and published by . This book was released on 2011 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lthough extensive research work has been carried out on the drag reduction behavior of polymers and surfactants alone, little progress has been made on the synergistic effects of combined polymers and surfactants. A number of studies have demonstrated that certain types of polymers and surfactants interact with each other to form surfactant-polymer complexes. The formation of such complexes can cause changes in the solution properties and may result in better drag reduction characteristics as compared with pure additives. A series of drag-reducing surfactants and polymers were screened for the synergistic studies. The following two widely used polymeric drag reducing agents (DRA) were chosen: a copolymer of acrylamide and sodium acrylate (referred to as PAM) and polyethylene oxide (PEO). Among the different types of surfactants screened, a cationic surfactant octadecyltrimethylammonium chloride (OTAC) and an anionic surfactant Sodium dodecyl sulfate (SDS) were selected for the synergistic study. In the case of the cationic surfactant OTAC, sodium salicylate (NaSal) was used as a counterion. No counterion was used with anionic surfactant SDS. The physical properties such as viscosity, surface tension and electrical conductivity were measured in order to detect any interaction between the polymer and the surfactant. The drag reduction (DR) ability of both pure and mixed additives was investigated in a pipeline flow loop. The effects of different parameters such as additive concentration, type of water (deionized (DI) or tap), temperature, tube diameter, and mechanical degradation were investigated. The addition of OTAC to PAM solution has a significant effect on the properties of the system. The critical micelle concentration (CMC) of the mixed surfactant-polymer system is found to be different from that of the surfactant alone. The anionic PAM chains collapse upon the addition of cationic OTAC and a substantial decrease in the viscosity occurs. The pipeline flow behaviour of PAM/OTAC mixtures is found to be consistent with the bench scale results. The drag reduction ability of PAM is reduced upon the addition of OTAC. At low concentrations of PAM, the effect of OTAC on the drag reduction behavior is more pronounced. The drag reduction behavior of polymer solutions is strongly influenced by the nature of water (de-ionized or tap). The addition of OTAC to PEO solution exhibited a week interaction based on the viscosity and surface tension measurements. However, the pipeline results showed a considerable synergistic effect, that is, the mixed system gave a significantly higher drag reduction (lower friction factors) as compared with the pure additives (pure polymer or pure surfactant). The synergistic effect in the mixed system was stronger at low polymer concentrations and high surfactant concentrations. Also the resistance against mechanical degradation of the additive was improved upon the addition of OTAC to PEO. The mixed PEO/SDS system exhibited a strong interaction between the polymers (PEO) and the surfactant (SDS), Using electrical conductivity and surface tension measurements, the critical aggregation concentration (CAC) and the polymer saturation point (PSP) were determined. As the PEO concentration is increased, the CAC decreases and the PSP increase. The addition of SDS to the PEO solution exhibits a remarkable increase in the relative viscosity compared to the pure PEO solution. This increase is attributed to the changes in the hydrodynamic radius of the polymer coil. The pipeline flow exhibited a considerable increase in DR for the mixed system as compared to the pure PEO solution. The addition of surfactant always improves the extent of DR up to the PSP. Also the mixed PEO/ SDS system shows better resistance against shear degradation of the additive.

Download or read book Reduction of Drag by Addition of Polymers to Water written by James Robert Falender and published by . This book was released on 1965 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments on Polymer Drag Reduction Using PIV and PLIF written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of turbulence in a drag reduced flat plate boundary layer has been studied with particle image velocimetry (PlV) and planar laser induced fluorescence (PLIF). Drag reduction was achieved by injection of a solution of water-soluble polymer through a spanwise slot near the leading edge of the flat plate. Velocity and concentration data were obtained using PrV and PLIF, respectively, in planes parallel to the wall (x-z plane) and perpendicular to the wall (x-y plane). Measurements of velocity, vorticity and streak spacing were obtained and trends analyzed. For increasing drag reduction, damping of streak oscillations, suppression of streak splitting and merging, streak stabilization and coarsening of the low speed streaks was observed. PLIF measurements of the injected polymer solution showed that regions of high polymer concentration are correlated with the low speed streaks. PW measurements in the x-y plane showed that at Maximum Drag Reduction (MDR) there are sighificant differences in the statistics of turbulence between boundary layers with polymer injection and channel flow with an ocean of polymer suggesting that in this sense, the achievement of MDR in flows with polymer addition is not unique.

Download or read book Transient Aspects of the Polymer Induced Drag Reduction Phenomenon written by Anselmo Soeiro Pereira and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addition of a small amount of polymers of high molecular weight can lead to a pressure drop decrease in turbulent flows. The polymers successively stretch and coil by interacting with the turbulent structures, which imposes a transient behaviour on the drag reduction (DR). As a result, DR undergoes three stages over time: A, B, and C. In stage A, DR departs from zero and assumes negative values due to a significant polymer stretching at the beginning of the process, which requires energy from the flow. After the minimum DR is reached, the polymers start their coil-stretch cycle and DR increases in response to the development of turbulent structures, achieving a maximum value, which makes for the beginning of stage B. However, during their coil-stretch cycle, polymers can be mechanically degraded as a result of an intense polymer stretching, which reduces their ability to act as energy exchange agents. Hence, when polymer degradation becomes pronounced, DR decreases until achieving a final value. The polymer degradation process characterizes the stage C. In the present work, numerical analyses are conducted aiming to investigate the stages A, B and C. The transient aspects of the polymer induced drag reduction phenomenon are explored with the aid of direct numerical simulations of turbulent plane Poiseulle and Couette flows of viscoelastic FENE-P fluids taking into account a large range of Reynolds number, Weissenberg number and maximum polymer molecule extensibility. Stages A and B are carefully studied from tensor, energy budget and spectral perspectives. A polymer scission model is developed in order to numerically reproduce the stage C.

Download or read book Investigating the Effect of Polymer Molecular Weight on Drag Reduction Performance Using Rotating Disk Apparatus RDA written by Nurul Fatimah Abdul Basir and published by . This book was released on 2013 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of turbulent drag reduction, which is caused by the addition of a small amount of polymer or some other substances to the liquids flowing systems has been the focus of attention of many scientists for the last decades. Due to the reduction of the drag, pumping power for the pipeline will significantly reduced and thus will decrease the cost of electricity in total production cost. In this study, the effect of the presence of a drag reducing agent (DRA) and its variety of molecular weight on the torque produced in rotating disk apparatus containing water is investigated. The experimental procedure was divided into three parts; obtaining several different polymer molecular weights using ultrasonication method, testing the water using different polymer molecular weight at different polymer concentration and lastly is adding the different concentration of surfactant in the fixed concentration of water- polymer solution. Three polymer molecular weights are obtained by using ultrasonificator method with value of 11.7967 x106 g/mol, 4.830 x106 g/mol and 1.7179 x106 g/mol. A drastic reduction of drag in the turbulent flow of solutions as evaluated with torque differences in comparison to the pure solvent can be observed, even when only minute amounts of the additives are added. The percentage of drag reduction is relatively increases as we increase the polymer molecular weight and polymer concentration. A maximum drag reduction of 47.62% has been observed at polymer molecular weight of 11. 7697 x106 with polymer concentration of 200 ppm. In polymer- surfactant complex solution, 29% of drag reduction were reported with surfactant concentration of 2000ppm.

Download or read book Rheology of Drag Reducing Fluids written by Aroon Shenoy and published by Springer Nature. This book was released on 2020-03-25 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: ​This book explains theoretical derivations and presents expressions for fluid and convective turbulent flow of mildly elastic fluids in various internal and external flow situations involving different types of geometries, such as the smooth/rough circular pipes, annular ducts, curved tubes, vertical flat plates, and channels. Understanding the methodology of the analyses facilitates appreciation for the rationale used for deriving expressions of parameters relevant to the turbulent flow of mildly elastic fluids. This knowledge serves as a driving force for developing new ideas, investigating new situations, and extending theoretical analyses to other unexplored areas of the rheology of mildly elastic drag reducing fluids.The book suits a range of functions--it can be used to teach elective upper-level undergraduate or graduate courses for chemical engineers, material scientists, mechanical engineers, and polymer scientists; guide researchers unexposed to this alluring and interesting area of drag reduction; and serve as a reference to all who want to explore and expand the areas dealt with in this book.

Download or read book An Experimental Study of Polymer Drag Reduction and Boundary Layer Diffusion Characteristics for Incompressible Flow Over a Flat Plate written by John Miguel and published by . This book was released on 1978 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drag reduction by injection of high molecular weight polymers into boundary layers has been demonstrated repeatedly in the past. However, from a volume utilization tradeoff standpoint, the quantities of polymer required make the gains achieved by this process marginal. While indicating reduced polymer requirements for drag reduction, limited data obtained from pipe flow and external boundary layer flow experiments are conflicting and hard to interpret. Ambiguities in measurement techniques due to polymer effects on commonly used instrumentation and opposing features of varied flow facilities have also contributed to making these earlier works contradictory and difficult to resolve. Experiments performed in this research indicate that turbulence intensity distributions are altered by the addition of polymer in such a way that the peak of turbulence production is lowered and its location moved away from the wall. The transition region is delayed and extended by the addition of polymer to the boundary layer. The laminar sublayer of boundary layer profiles appears to have thickened due to the addition of polymer. When compared to the law of the wall corrected for developing flow, the velocity profiles also show evidence of a thickened sublayer.

Download or read book Drag reduction Characteristics of Ionic Polymers in the Presence and Absence of an Electrical Charge written by Leonard Carter and published by . This book was released on 1975 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of flow-drag measurements was made to determine whether the drag reduction characteristics of ionic polymer compounds are altered by the presence of an electrical charge. A rotating disk apparatus was used to generate torque and to transfer an electrical charge to dilute polymer solutions. In addition, the uncharged drag-reduction properties of nine dilute polymer solutions were measured. No measurable dependence of drag reduction on electrical charge could be observed.

Download or read book Investigations on Drag Reduction by Interactions Between Polymer and Surfactant and Polymer and Polymer written by Jia Yang and published by . This book was released on 2015 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large amount of studies have been carried out on pipeline flow with several kinds of drag reducing agents, especially polymers and surfactants. Drag reducing agents, by definition, are additives which help suppress or eliminate turbulence in a pipeline. The mechanism and methodology of polymer only or surfactant only as drag reducing additives have been fully discovered. Whether mixed drag reducers such as polymer-surfactant or polymer-polymer systems would be effective is still not clear. In our study, polymer-surfactant and polymer-polymer mixed additives are used in order to explore the synergistic effects and interactions in pipeline flow loops. The experimental work was divided into two sections: bench-scale experiments and pilot-scale experiments. In bench-scale experiments, the properties of prepared fluids such as, surface tension, conductivity and shear viscosity were measured. Several comparison methods and calculations were applied to give better understandings of the properties resulting from mixing of polymer with surfactant and polymer with polymer. After analysis of the properties, several combinations of concentrations were selected and solutions were prepared in the main tank of pilot plant and pumped into the pipeline set-up to test the pipeline flow behaviors. Turbulence structure/Reynolds number, pipe diameter, polymer-surfactant concentration were all considered as influencing factors. Critical micelle concentration, critical aggregation concentration, polymer saturation point, the onset of drag reduction, and the interactions between the mixed additives were discussed. A comparison between pipeline results and the predictions of Blasius Equation or Dodge-Metzner Equation were also discussed.. For polymer-surfactant studies, a commonly used polymer additive - carboxylmethylcellulose (referred to as CMC which is anionic) was selected as the drag reducing agent. The performance of this polymer was investigated in the presence of six surfactants respectively - Alcohol ethoxylate (referred to as Alfonic 1412-9 and Alfonic 1412-3 which are nonionic), Aromox DMC (nonionic surfactant), Stepanol WA-100 and Stepwet DF-95 (which mainly consist sodium lauryl sulfates, anionic surfactant) and Amphosol (which is zwitterionic).The experiments were first conducted with pure CMC solution with different concentrations (100ppm, 500ppm, 700ppm and 1000ppm) as a standard. The 500ppm CMC solution was selected as the best polymer concentration with highest drag reduction efficiency. For polymer-surfactant combinations, CMC-Alfonic 1412-9, CMC-Alfonic1412-3, CMC-Stepanol and CMC-Stepwet systems were found to have significant interactions. High surfactant concentration resulted in reduction in %DR. The addition of Aromox increased the drag reduction ability and onset point when concentration was higher than the polymer saturation points. Also, both hydrophobic and electrostatic interactions were thought to have an effect on critical micelle concentration, which led to the fluctuations in the %DR. For polymer-polymer studies, PAM-PEO system at two different polymer concentrations were investigated. Overall, Pure PAM solution had much higher drag reduction ability than pure PEO solutions. Mixing them together, strong interactions occurred when PEO fraction was high (over 50%) which affected %DR and shear viscosity substantially. Power-law constants n and k were also taken into account and found to exhibit opposite trends with the increase of PEO fraction.

Download or read book Drag Reduction by Polymer Additives written by and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Drag Reduction with Polymer Additives written by Quan Si Truong and published by . This book was released on 1974 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulent Drag Reduction by Surfactant Additives written by Feng-Chen Li and published by John Wiley & Sons. This book was released on 2012-01-10 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Experimental Investagation of Drag Reduction Effects of Polymer Additives on Turbulent Pipe Flow written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.