Wall Versus Centerline Polymer Injection in Turbulent Channel Flows

Kim, K.; Sirviente, A. I.

doi:10.1007/s10494-006-9054-2

Cited by 5 publications

(2 citation statements)

References 28 publications

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“…The majority of existing experimental studies on turbulence in polymer solutions were carried out in pipe flows (see, e.g., Virk et al 1967;Patterson, Zakin & Rodrigue 1969;Den Toonder et al 1997;Escudier, Presti & Smith 1999;Warholic, Massah & Hanratty 1999;Kim & Sirviente 2007), with only a few investigations in grid-generated turbulence (Gadd 1965;Barnard & Sellin 1969;Friehe & Schwarz 1970;McComb, Allan & Greated 1977;van Doorn, White & Sreenivasan 1999) or other 'washing-machine-like' configurations producing nearly homogeneous and isotropic turbulence (Liberzon et al 2006(Liberzon et al , 2009. The difference between the effect of polymers on turbulence without and with mean shear is that in the former case the polymers can only provoke additional local energy dissipation, while in the latter case they can in addition modify the mean shear and with it long-range energy exchange by instabilities.…”

Section: Introductionmentioning

confidence: 99%

Grid turbulence in dilute polymer solutions: PEO in water

Vonlanthen

Monkewitz

2013

J. Fluid Mech.

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Grid turbulence of polyethylene oxide (PEO) solutions (Polyox WSR-301 in H 2 O) has been investigated experimentally for three concentrations of 25, 50 and 100 weight ppm, at a turbulence Reynolds number based on a Taylor microscale of Re λ ≈ 100. For the first time, time sequences of turbulence spectra have been acquired at a rate of 0.005 Hz to reveal the spectral evolution due to mechanical degradation of the polymers. In contrast to spectra averaged over the entire degradation process, the sequence of spectra reveals a clear but time-dependent Lumley scale at which the energy spectrum changes abruptly from the Kolmogorov κ −5/3 inertial range to a κ −3 elastic range, in which the rate of strain is maintained constant by the polymers. The scaling of the initial Lumley length with Kolmogorov dissipation rate 0 and molecular weight is determined, and a cascade model for the temporal decrease of molecular weight, i.e. for the breaking of polymer chains is presented. Finally, a heuristic model spectrum is developed which covers the cases of both maximum and partial turbulence reduction by polymers.

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Section: Introductionmentioning

confidence: 99%

Grid turbulence in dilute polymer solutions: PEO in water

Vonlanthen

Monkewitz

2013

J. Fluid Mech.

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“…Previous studies showed that this heterogeneous injection method with a diaphragm pump prevented mechanical degradation of the DRAs and led to optimal drag reduction performance . Also, the master solutions are injected at the wall (rather than centre) of the pipe as suggested by previous studies for better drag reduction efficiency . The concentration of all PEO concentrated solutions (with PEOs of three molecular weights) is 750 ppm, and the concentration in the pipeline is 5, 10, 15, and 20 ppm with four different flow rates.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Experimental correlation for pipe flow drag reduction using relaxation time of linear flexible polymers in a dilute solution

et al. 2019

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In this study, we investigate the drag reduction property of a linear flexible polymer, PEO (polyethylene oxide) in a fully turbulent pipe flow. The aim of this study is to develop a correlation to predict the drag reduction using the Weissenberg number, a dimensionless number related to the relaxation time of the polymer and the polymer concentration in dilute solutions. The physical meaning of the relaxation time of polymers and overlap concentration between the dilute and semi-dilute polymer solution are clarified. A higher polymer concentration, Reynolds number, and Weissenberg number lead to an increasing drag reduction. A semi-empirical correlation to predict the drag reduction with two dimensionless variables mentioned above is established and can predict the experimental data in this work and other previous works well. Previous correlations that use Reynolds number often require high flow velocity or large pipes in the experimental setup to predict drag reduction in large-scale industrial applications, which involves extra cost and potential safety issues. The current new correlation method uses relatively low velocities to avoid the problems mentioned above. K E Y W O R D Sdrag reduction, pipe flow, polymer, relaxation time, Weissenberg number

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Shear layers in the turbulent pipe flow of drag reducing polymer solutions

Zadrazil

Bismarck

Hewitt

et al. 2012

Chemical Engineering Science

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A range of high molecular weight polymers (polyethylene oxide) was dissolved at very low concentrations -in the order of few wppm -in a solvent (water).The Newtonian character of the polymer solutions was confirmed by rheological measurements. The polymer solutions were then pumped through a long horizontal pipe section in fully developed turbulent conditions. The flow experienced a reduction in frictional drag when compared to the drag experi- continuously formed close to the wall at a random frequency and move towards the pipe centerline until they eventually disappear, thus occupying or existing within a "shear layer region". It is found that the mean thickness of the shear layer region is correlated with the measured level of drag reduction.The shear layer region thickness is increased by the presence of polymer additives when compared to the pure solvent, in a similar way to the thickening of the buffer layer. The results provide valuable insights into the characteristics of the turbulent pipe flow of a solvent containing drag reducing polymers that can be used to further our understanding of the role of polymers on the mechanism of drag reduction and to develop advanced drag reduction models.

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Wall Versus Centerline Polymer Injection in Turbulent Channel Flows

Cited by 5 publications

References 28 publications

Grid turbulence in dilute polymer solutions: PEO in water

Grid turbulence in dilute polymer solutions: PEO in water

Experimental correlation for pipe flow drag reduction using relaxation time of linear flexible polymers in a dilute solution

Shear layers in the turbulent pipe flow of drag reducing polymer solutions

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