The effects of turbulence on the flow characteristics of model fibre suspensions

Bobkowicz, A. J.; Gauvin, W. H.

doi:10.1016/0009-2509(67)80015-0

Cited by 27 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The improved mixing for the short‐fiber hardwood pulp suspension coincides with results reported by Luettgen et al, who also found that turbulent dispersion was greater for a dilute hardwood suspension (at C m = 0.5%) than for fiber‐free water. The results also agree with findings summarized by Bobkowicz and Gauvin, who reported that the radial intensity of turbulence in water flow containing short nylon fibers (of length from 0.52 to 1.21 mm) was higher than that for water without fibers, even though the suspension flow was in the drag reduction regime. It is generally believed that drag reduction is due to the suppression of turbulent eddies by fibers or other particles.…”

Section: Resultssupporting

confidence: 92%

“…However, for non‐Newtonian pulp suspensions few studies have been conducted to study in‐line jet mixing behavior and the data are very limited. Bobkowicz and Gauvin examined the distribution of hot water in nylon‐fiber suspension flow in a vertical flow loop of diameter 50.8 mm. The tracer was injected at the pipe axis, and the radial temperature profile was measured by a temperature probe.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

In‐line jet mixing of liquid‐pulp‐fiber suspensions: Effect of fiber properties, flow regime, and jet penetration

et al. 2012

View full text Add to dashboard Cite

Mixing effectiveness was determined experimentally for side jet injection into pipe flow for water and pulp suspensions for a range of fiber mass concentrations (0-3.0%), mainstream velocities (0.5-5.0 m/s), and side-stream velocities (1.0-12.7 m/s). The mixing quality was measured in cross-sectional planes along the pipe using electrical resistance tomography and quantified by a modified mixing index, derived from the coefficient of variation of conductivity. Mixing depended strongly on the flow regime and jet penetration. For turbulent flow, the criteria for in-line jet mixing in water are applicable to the mixing in suspensions, with small differences likely due to differences in fiber network strength and influences of fiber-turbulence interactions in modifying turbulent structures in the bulk. When a suspension flows as a plug, however, the mixing differs greatly from that in water, depending on the fiber network strength in the core of the pipe.

show abstract

Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

In‐line jet mixing of liquid‐pulp‐fiber suspensions: Effect of fiber properties, flow regime, and jet penetration

et al. 2012

View full text Add to dashboard Cite

show abstract

“…23 It is possible that the polar moment of inertia perpendicular to the longitudinal axis of the molecule (assuming that the coils tend to straighten as they are spun by the eddy) provides sufficient inertial resistance to rotational acceleration to decrease the underpressure in the vortex core and reduce the production of small scale turbulence. This resistance to rotational acceleration could explain the drag reduction found in fiber suspensions 50 where no viscoelasticity is present.…”

Section: Discussionmentioning

confidence: 96%

Effect of Drag-Reducing Additives on Boundary-Layer Turbulence

Johnson

Barchi

1968

Journal of Hydronautics

View full text Add to dashboard Cite

A preliminary investigation has been made concerning the effects of polyethylene oxide on the spectral density of turbulent fluctuations in a boundary layer. The Polyox solution was injected into a two-dimensional boundary layer along a flat plate which was towed at 9.5 fps in the Naval Academy's 85-ft tow tank. Measurements of the mean and fluctuating components of the velocity near the wall were made with conical hot film sensors. Polymer injection resulted in an increase in rms level of the fluctuations and in an increase in spectral density below 200 Hz. Above this frequency, the spectral density decreased, the effect being more pronounced at higher frequencies and at higher polymer concentrations. Measurements of the mean and fluctuating components of the wall shear stress were made with flush-mounted hotfilm sensors submerged in the viscous sublayer. Polymer injection resulted in a decrease in mean shear, in rms level, and in spectral density of the fluctuating wall shear stress. The latter effect increased with increasing frequency and all effects increased with higher molecular weight of the additives. All results suggest the polymer shifts the scale of turbulence away from the energy-dissipating small eddies. Nomenclature A = bridge voltage squared at zero flow B = King's formula constant db = decibels (•• -fluctuating voltage CL = fluctuating linearized voltage Ei, = anemometer bridge voltage Eh = time-averaged bridge voltage EL = linearized voltage / = frequency F c (f) = normalized voltage spectral density F,t(f) = normalized velocity spectral density G x (f) = power spectral density of quantity x in a 1-11/ band l7. r (/)A/ = power spectral density of quantity x in a yVoctave band k\ = one-dimensional wave number K = constant m = linearizer exponent n = King's formula exponent Af = temperature difference between sensor and environment TJ. -turbulence intensity n = fluctuating local velocity V = local velocity I? = time-average local velocity r\ : = convection velocity T W = wall shear stress TV = time-averaged wall shear stress r,,/ = fluctuating wall shear stress

show abstract

Polymer miscibility in organic solvents and in plasticizers—a two‐dimensional approach

Chen

1971

J of Applied Polymer Sci

View full text Add to dashboard Cite

SynopsisFrom thermodynamic considerations based on associated solution models and from the Hansen's three-dimensional solubility parameter concept, it is found that the solvent power of an organic liquid for a given polymer can be characterized by two parameters, 8,, and xH, where 6, is the hydrogen-bonding solubility parameter of the liquid, and xH is a term which takes account of the dispersion and polar interactions between the liquid and the polymer and of the effects due to temperature and molecular size of the liquid. It is also found that Hansen's solubility sphere for the polymer can be represented as a solubility circle in the proposed X K~, , plane. The proposed approach is applied ~uccess-fully t o polymer-plasticizer systems.

show abstract

The effects of turbulence on the flow characteristics of model fibre suspensions

Cited by 27 publications

References 15 publications

In‐line jet mixing of liquid‐pulp‐fiber suspensions: Effect of fiber properties, flow regime, and jet penetration

In‐line jet mixing of liquid‐pulp‐fiber suspensions: Effect of fiber properties, flow regime, and jet penetration

Effect of Drag-Reducing Additives on Boundary-Layer Turbulence

Polymer miscibility in organic solvents and in plasticizers—a two‐dimensional approach

Contact Info

Product

Resources

About