Shear Stresses on the Walls of Agitated Vessels

Wichterle, Kamil; Žák, Leo; Mitschka, P.

doi:10.1080/00986448508911652

Cited by 14 publications

(6 citation statements)

References 12 publications

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“…In the region of impeller stream impact (near z/H = 0.34) a decrease of dimensionless shear rate values has been observed. Possibly, it is connected with an appearance in this place of stagnation point, what is confirmed by observations of Wichterle et al [21]. The distributions of the dimensionless shear rate along dimensionless coordinates z/H for impellers studied are shown in Figs.…”

Section: Distribution Of Hydrodynamic and Heat Transfer Coefficients supporting

confidence: 80%

See 1 more Smart Citation

Determination of the flow and heat transfer characteristics in non-Newtonian media agitated using the electrochemical technique

Broniarz-Press

Różańska

2008

International Journal of Heat and Mass Transfer

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Section: Distribution Of Hydrodynamic and Heat Transfer Coefficients supporting

confidence: 80%

“…Previous literature [21][22][23][24][25][26][27] has not paid sufficient attention to introduce the electrochemical method to determination of the flow and heat transfer characteristics of the stirring when the non-Newtonian liquids are the media agitated.…”

Section: Introductionmentioning

confidence: 99%

Determination of the flow and heat transfer characteristics in non-Newtonian media agitated using the electrochemical technique

Broniarz-Press

Różańska

2008

International Journal of Heat and Mass Transfer

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“…Local shear rate γ and friction coefficient f near-wall region of the stirred tank were calculated from the formulas proposed by Wichterle et al and Zak normalγ = ( I normald 2.156 z normale F D normalA 2 / 3 C normalA normalo R normalc 5 / 3 ) 3 and f = normalτ T 2 normalρ n 2 D 4 where I d is measured diffusion current and shear stress τ on a wall is correlated with shear rate as normalτ = normalη normalγ Local values of the dynamic velocity v ∗ and energy dissipated ε were also computed from the following equations v ∗ = normalτ normalρ normalε = normalτ normalγ normalρ The measurements were carried out for different agitator speeds n within the turbulent regime of the Newtonian liquid flow in the agitated vessel. On the basis of the 5120 experimental data of the diffusion current, local values of the shear rate γ, friction coefficient f , shear stress τ, dynamic velocity v ∗ , and energy dissipated ε were calculated.…”

Section: Methodsmentioning

confidence: 99%

Local Momentum Transfer Process in a Wall Region of an Agitated Vessel Equipped with an Eccentric Impeller

Cudak

Karcz

2011

Ind. Eng. Chem. Res.

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The results of the experimental studies of local momentum transfer process in the region of the cylindrical wall of an agitated vessel equipped with an eccentric axial flow impeller are presented. The data for eccentrically located impellers both, propeller and HE 3 impeller, differing in the operating liquid pumping mode were compared. In total, 5120 experimental points for both impellers were obtained on the basis of the electrochemical experiments for each of the tested impeller. Axial and angular distributions of the shear rate and friction coefficient in the agitated vessel without baffles were found within the turbulent regime of the Newtonian liquid flow. Local shear stress, dynamic velocity and energy dissipated were also identified in this region of the wall. The results of the study show that the profiles of the transport coefficients depend strongly on the eccentricity e/R, axial and angular coordinates, liquid circulation imposed by axial flow impeller, and liquid turbulence in the agitated vessel. The distributions of the quantities which describe momentum transfer process in the region of the cylindrical wall of the agitated vessel as the function of the e/R, z/H, j/2π, and Re number were approximated mathematically for both impellers by means of eqs 6-9. Averaged values of the local quantities, obtained as a result of the numerical integration, were described by means eqs 12-17. The eqs 6-9 and 12-17 have no equivalent in the open literature concerning this subject.

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“…Aggregates that are sufficiently strong to withstand disruption in the bulk flow could well be disrupted in one of the other two zones. Wichterle et al (1985) measured shear rates at the walls of a stirred tank. Highest shear rates occurred in the wall region at the height of the impeller, and may reach a value as high as one-third of the maximum shear rate at the impeller blades.…”

Section: Turbidimetric Methodsmentioning

confidence: 99%

Stirred Tanks

2008

Step‐Growth Polymerization Process Modeling and Product Design

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Shear Stresses on the Walls of Agitated Vessels

Cited by 14 publications

References 12 publications

Determination of the flow and heat transfer characteristics in non-Newtonian media agitated using the electrochemical technique

Determination of the flow and heat transfer characteristics in non-Newtonian media agitated using the electrochemical technique

Local Momentum Transfer Process in a Wall Region of an Agitated Vessel Equipped with an Eccentric Impeller

Stirred Tanks

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