scholarly journals Study the Characterization of Adding Polymer-Surfactant Agent on the Drag Reduction Phenomena in Pipeline Flow System

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Sahar A. Dawood
Keyword(s):  
Aqueous Solution ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Friction Factor ◽  
Methyl Cellulose ◽  
Fluid Properties ◽  
Maximum Drag Reduction ◽  
Polymer Surfactant ◽  
Good Agreement

  Abstract     In this study, the effect of carboxylic methyl cellulose (CMC), and sodium dodcyl benzene sulfonate (SDBS) as an aqueous solution on the drag reduction was investigated. Different concentrations of (CMC) and (SDBS) such as (50, 100, 150, 200, 250, 300, 350, 400, 450, and 500 ppm) were used to analyze the aqueous solution properties, including surface tension, conductivity, and shear viscosity. The optimum four concentrations (i.e., 50, 100, 200, and 300 ppm) of fluid properties were utilized to find their effect on the drag reduction. Two different PVC pipe diameters (i.e., 1" and 3/4") were used in this work. The  results showed that blending CMC with SDBS gives a good drag reduction percent about (58%) more than using them individually, friction factor decreasing with increasing Reynolds number and gives good agreement with von Karamn equation and maximum drag reduction (MDR) asymptote. Reynolds number, pipe diameter, and polymer-surfactant concentrations were considered as influencing factors. In addition, critical micelle concentration, the onset of drag reduction, and the interactions between the mixed additives were discussed.  Keyword: CMC, SDBS, drag reduction, friction factor, blending of additives.

Drag Reduction of Bamboo and Abaca Fiber Suspensions in Circular Pipe

2013 ◽  
Vol 388 ◽  
pp. 34-39 ◽  
Author(s):  
Gunawan Kapal ◽  
M. Baqi ◽  
S. Fathernas ◽  
Yanuar
Keyword(s):  
Aqueous Solution ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Aqueous Solutions ◽  
Drag Reduction ◽  
High Reynolds Number ◽  
Circular Pipe ◽  
Fiber Suspensions ◽  
Maximum Drag Reduction ◽  
High Reynolds

The drag reduction of dispersions of fibers in aqueous solutions of was studied as a function of concentration with a circular pipe apparatus. Experiments were carried out by measuring the pressure drop. The purpose of this research is to investigate the reduction of pressure drop in a circular pipe with the addition fiber in aqueous solution. Circular pipe with 4 mm of diameter is used in this study. Concentration of bamboo and abaca fibers solutions are 200 ppm and 300 ppm. It was found that fibers solutions give rise to drag reduction in turbulent flow range. Experimental was conducted from low to high Reynolds number up to 55,000. We observed a maximum drag reduction ratio of 7 % at Reynolds number about 35,000 and found that increased by increasing a concentration of fiber solution.

Characterization of drag reduction performance over rotating microgrooves with different cross-sections

2019 ◽  
Vol 234 (6) ◽  
pp. 1746-1758
Author(s):  
Suping Wen ◽  
Wenbo Wang ◽  
Zhixuan Zhang
Keyword(s):  
Drag Reduction ◽  
Cross Sections ◽  
Turbulence Intensity ◽  
Reynolds Numbers ◽  
Cross Sectional ◽  
Dimensionless Velocity ◽  
Velocity Shift ◽  
Maximum Drag Reduction ◽  
Sectional Parameters

This paper presents a study of cross-sectional parameters and optimal drag reduction performance specifically for drag reduction in rotating microgroove applications. Rotating triangular microgrooves with nine asymmetrical and symmetrical cross-sections were numerically studied. In addition, a representative symmetrical rotating microgroove was experimentally tested. Positive asymmetrical microgrooves (including symmetrical microgrooves) were found to be sensitive to rotating Reynolds numbers and produced more significant drag reduction. Compared with a dimensioned asymmetry variable and other dimensionless parameters, the dimensionless asymmetry variable i+ could be used to describe drag reduction performance, which captured both the influence of microgroove cross-sectional asymmetry and turbulence intensity. A maximum drag reduction of up to 8.9% was obtained at 9.2 i+. With the exception of the torque, the velocity shift obtained from dimensionless velocity profiles could also be used to predict drag reduction performance, which has the potential for wider and more comprehensive application for any drag reduction technology.

An Experimental and Analytical Investigation of Friction Factors for Fully Developed Flow in Internally Finned Triangular Ducts

1986 ◽  
Vol 108 (3) ◽  
pp. 507-512 ◽  
Author(s):  
H. Chegini ◽  
S. K. Chaturvedi
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Reynolds Numbers ◽  
Analytical Investigation ◽  
Momentum Equation ◽  
Fully Developed Flow ◽  
Finite Difference Technique ◽  
Friction Factors ◽  
Experimental Values ◽  
Good Agreement

Friction factors for fully developed flow in triangular ducts with fins of various height and width are investigated for Reynolds numbers ranging from 150 to 90,000. Two triangular ducts having apex angles of 60 and 38.8 deg are studied. Results are presented in the form of standard plots of friction factor as a function of Reynolds number. Friction factor values for the smooth triangular duct cases are in good agreement with the existing results. For the finned-duct cases, the fully developed axial velocity profiles in laminar flow are determined by solving the x-momentum equation iteratively by the Gauss–Seidel finite-difference technique. The theoretically determined friction factors for these cases are in good agreement with the experimental values of friction factors based on pressure drop measurements.

A unified correction method for Reynolds number, size, and roughness effects on the performance of compressors

2011 ◽  
Vol 225 (7) ◽  
pp. 864-876 ◽  
Author(s):  
M V Casey ◽  
C J Robinson
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Friction Factor ◽  
Critical Reynolds Number ◽  
Pressure Rise ◽  
Correction Method ◽  
Roughness Effects ◽  
Wide Range ◽  
Fluid Properties ◽  
The Individual

An equation is derived that relates the changes in turbomachinery efficiency with Reynolds number to the changes in the friction factor of an equivalent flat plate. This equation takes into account the different Reynolds number and roughness dependencies of the individual components, and can be used for whole stages and multistage machines. The new method is sufficiently general to correct for changes in Reynolds number due to changes in fluid properties or speed, changes in machine size, or changes in the surface roughness of components for all types of turbomachinery, but is calibrated here for use on axial and radial compressors. The method uses friction factor equations for a flat plate which include fully rough behaviour above an upper critical Reynolds number, a transition region depending on roughness and a region with laminar flow below the lower critical Reynolds number. The correction equation for efficiency includes a single empirical factor. Based on a simple loss analysis and a calibration with over 30 sets of experimental test data covering a wide range of machine types, a suggestion for the variation of this factor with specific speed has been made. Additional correction equations are derived for the shift in flow and the change in pressure rise with Reynolds number and these are also calibrated against the same data.

Drag Reduction in Turbulent Flow With Polymer Additives

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Shu-Qing Yang
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Friction Factor ◽  
Turbulent Flows ◽  
Polymer Additives ◽  
Damping Factor ◽  
Mixing Length ◽  
Mean Velocity ◽  
Turbulent Momentum ◽  
Flow Drag

The mean velocity profile and friction factor in turbulent flows with polymer additives are investigated using Prandtl’s mixing-length theorem. This study reveals that the mixing-length theorem is valid to express the drag-reducing phenomenon and that the presence of polymer additives increases the damping factor B in van Driest’s model; subsequently reducing the mixing-length, this interprets that the polymer hampers the transfer of turbulent momentum flux, the velocity is increased, and flow drag is reduced. This study also discusses the onset Reynolds number for drag reduction to occur. The predicted velocity, friction factor, and onset Reynolds number are in good agreement with the measured data in the literature.

scholarly journals Numerical analysis on heat transfer and flow resistance performances of a heat exchanger with novel perforated wavy fins

2021 ◽  
pp. 255-255
Author(s):  
Xuexi Wang ◽  
Feng Lin
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Friction Factor ◽  
Wave Amplitude ◽  
Numerical Study ◽  
Inlet Temperature ◽  
S Wave ◽  
Air Inlet ◽  
Good Agreement

In this paper, the experimental and numerical study of thermo-hydraulic characteristics of perforated wavy fin heat exchanger and unperforated wavy fin heat exchanger were conducted. Firstly, the two kinds of fins were studied under different air inlet velocity and constant inlet temperature. The results show that Nusselt number increases with Reynolds number and friction factor decreases with Reynolds number. Then, the performance of the two kinds of fins is numerically analyzed, and the simulation results are in good agreement with the experimental data. On this basis, the influence of different perforated fin parameters (fin height H, fin pitch s, wave amplitude wa, perforation number n, perforation diameter d) on the thermal performance of wavy fin heat exchanger is discussed. It is indicated that friction factor and Nusselt number increase with increasing aperture, wave amplitude, fin pitch and perforation number or decreasing fin height under constant Reynolds number condition. Finally, the performance evaluation of heat exchangers with different parameters is carried out to obtain the best performance heat exchanger parameters, which can provide a reference for the design of the new wavy fin heat exchanger.

scholarly journals The Laminar-Turbulent Transition in Suspension Of Rigid Spheres

1967 ◽  
Vol 7 (03) ◽  
pp. 259-265 ◽  
Author(s):  
Irvin M. Krieger ◽  
James S. Dodge
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Friction Factor ◽  
Particle Diameter ◽  
Reynolds Numbers ◽  
Polymeric Fluids ◽  
Turbulence Suppression ◽  
Turbulent Transition ◽  
Polymer Latices ◽  
Critical Reynolds Numbers

Abstract The laminar-turbulent transition was studied for monodisperse rigid polymer latices as functions of particle diameter and concentration at several tube diameters. Breaks in the graph of friction factor vs Reynolds number were used to characterize the transition; rates of shear were sufficiently high so that Newtonian behavior at the high shear limiting viscosity could be assumed. No abnormal behavior was noted at concentrations below 30 volume percent. At higher concentrations, suppress ion of turbulence was observed with critical Reynolds numbers rising to as high as 5,500 at 50 volume percent. No definite effect on the transition was noted due to variation of particle size or tube diameter. The type of surfactant used to stabilize the latex was found to have an important influence on the critical Reynolds number. INTRODUCTION For some polymer solutions and solid-in-liquid suspensions, the transition from laminar behavior to turbulence in pipeline flow has been reported to take place at unusually low1-5 and in some cases at higher than normal6,7 critical Reynolds numbers. Extreme values of critical Reynolds numbers (NRe*) have been found to range from 1 to 6,000, as opposed to the values of 2,000 to 3,500 which are obtained for ordinary liquids. Observations have also been reported of drag reduction in fully developed turbulent flow, i.e., a decreased value of the friction factor in the Reynolds number-friction factor plot6,10-14 in colloidal and polymeric fluids. In some cases, turbulence suppression (unusually large values of NRe*) was noted to occur preceding the drag reduction,6 while a normal transition was noted in other cases of drag reduction.14 To relate the occurrence of turbulence suppression and drag reduction to the molecular or particulate structure of the fluid, it is desirable to characterize the structural variables with some precision. For most colloidal dispersions and polymeric fluids, this is very difficult; particle sizes, shapes and stiffnesses may vary over wide ranges in the same sample. Recently, however, a colloidal fluid has become available which consists of rigid spherical particles of highly uniform diameter dispersed in a simple Newtonian liquid. These are monodisperse polymer latices, prepared by carefully controlled emulsion polymerization reactions. The purpose of this research was to study the transition to turbulence in these well-characterized colloidal fluids a s a function of concentration, particle diameter and tube diameter.

Gas flow in micro-channels

1995 ◽  
Vol 284 ◽  
pp. 257-274 ◽  
Author(s):  
John C. Harley ◽  
Yufeng Huang ◽  
Haim H. Bau ◽  
Jay N. Zemel
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Friction Factor ◽  
Theoretical Investigation ◽  
Gas Flow ◽  
Slip Flow ◽  
First Order ◽  
Micro Channels ◽  
Theoretical Predictions ◽  
Good Agreement

An experimental and theoretical investigation of low Reynolds number, high subsonic Mach number, compressible gas flow in channels is presented. Nitrogen, helium, and argon gases were used. The channels were microfabricated on silicon wafers and were typically 100 μm wide, 104 μm long, and ranged in depth from 0.5 to 20 μm. The Knudsen number ranged from 10-3 to 0.4. The measured friction factor was in good agreement with theoretical predictions assuming isothermal, locally fully developed, first-order, slip flow.

scholarly journals Studying the Effect of Some Surfactants on Drag Reduction of Crude Oil Flow

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ali A. Abdul-Hadi ◽  
Anees A. Khadom
Keyword(s):  
Drag Reduction ◽  
Crude Oil ◽  
Solution Flow Rate ◽  
Additive Concentration ◽  
Solution Flow ◽  
Additive Type ◽  
Dimensionless Groups ◽  
Oil Flow ◽  
Maximum Drag Reduction ◽  
Good Agreement

The influence of SDBS, SLS, SLES, and SS as drag reducing agents on flow of Iraqi crude oil in pipelines was investigated in the present work. The effect of additive type, additive concentration, pipe diameter, solution flow rate, and the presence of elbows on the percentage of drag reduction (%Dr) and the amount of flow increases (%FI) was addressed. The maximum drag reduction was 55% obtained at 250 ppm SDBS surfactant flowing in straight pipes of 0.0508 m I.D. The dimensional analysis was used for grouping the significant quantities into dimensionless groups to reduce the number of variables. The results showed good agreement between the observed drag reduction percent values and the predicted ones with high value of the correlation coefficient.

Fluid Flow Characteristics in Microchannels With Rib-Patterned Surface

2011 ◽  
Author(s):  
Toru Yamada ◽  
Chungpyo Hong ◽  
Otto J. Gregory ◽  
Mohammad Faghri
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Flow Characteristics ◽  
Single Crystal Silicon ◽  
Working Fluid ◽  
Patterned Surfaces ◽  
Crystal Silicon ◽  
Wide Range ◽  
Fluid Flow Characteristics ◽  
Good Agreement

The effects of rib-patterned surfaces and surface wettability on liquid flow in microchannels were experimentally investigated in this study. Microchannels were fabricated on single-crystal silicon wafers by photolithographic and wet-etching techniques. Rib structures were patterned in the silicon microchannel, and the surface was chemically treated by trichlorosilane to create the hydrophobic condition. Experiments with water as the working fluid were performed with these microchannels over a wide range of Reynolds number between 110 and 1914. The results for the rib-patterned microchannels showed that the friction factor with the hydraulic diameter based on the rib-to-upper-wall height was lower than that for the incompressible theory with the same height. The friction factor-Reynolds number products for the hydrophobic condition increased as Reynolds number increased in the laminar flow regime. The experimental results were also compared with the predictive expressions from the literature, and it was found that the experimental data for the small rib/cavity geometry was in good agreement with those in the literature.

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