Flow generated by a disc turbine in aqueous solutions of polyacrylamide

Mishra, V. P.

doi:10.1016/s1385-8947(98)00112-0

Cited by 12 publications

(13 citation statements)

References 6 publications

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“…Firstly, it seems necessary to validate the CFD computer code; for this task, we have reffered to the review of Mishra et al (1998) and we have realized the same geometrical parameters.…”

Section: Resultsmentioning

confidence: 99%

“…We note that Mishra et al (1998) used laser Doppler anemometry to measure the flow generated by a disc turbine in aqueous solutions of polyacrylamide (PAA) (molecular weight: 5 x 10 6 -6 x 10 6 ) in a cylindrical tank. The tank diameter was 300 mm, with a flat bottom.…”

Section: Resultsmentioning

confidence: 99%

“…It is known that the dimension of the cavity behind an impeller blade increases with an increase in the impeller speed and a smaller cavity was found to form behind a concave blade (WARMOESKERKEN;SMITH, 1989). It has also been shown by Mishra and Joshi (1993) that the pumping capacity of a semi-circular blade impeller is much higher than that of a Rushton impeller. The cavity size and the pumping capacity are believed to change gradually with an increase in the blade curvature at least up to e = 0.5.…”

Section: Effect Of the Curvature Bladementioning

confidence: 99%

See 2 more Smart Citations

<b>Numerical investigation of flow induced by a disc turbine in unbaffled stirred tank</b> - doi: 10.4025/actascitechnol.v35i3.15554

Ameur

Bouzit

2013

Acta Sci. Technol.

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ABSTRACT. The flow generated by a disc turbine in a cylindrical unbaffled tank was numerically modeled. This study was carried out for shear-thinning fluids. Analyses concern the effect of impeller rotational speed, fluid rheology and impeller blade curvature on the mean velocities and power consumption. It was found that the cavern size and the power consumption are higher for extreme shear thinning fluids. It was found also that the best performance is achieved at high Reynolds number and flat-blade turbine. Predictions have been compared with literature data and a satisfactory agreement has been found.Keywords: numerical study, stirred tank, shear thinning fluid, disc turbine, impeller location, blade curvature.Investigação numérica do fluxo induzido por uma turbina de disco em 'unbaffled' tanque de agitação RESUMO. O fluxo gerado por uma turbina de disco em um tanque cilíndrico unbaffled foi numericamente modelada. Este estudo foi realizado para corte fino fluidos. As análises dizem respeito ao efeito da velocidade de rotação do rotor, reologia de fluidos e curvatura da lâmina do rotor na velocidade média e consumo de energia. Verificou-se que o tamanho da caverna eo consumo de energia são maiores para diluir os fluidos de corte extremas. Verificou-se também que o melhor desempenho é alcançado em número de Reynolds alto e flat-blade turbina. Previsões foram comparados com dados da literatura e um acordo satisfatório foi encontrado.Palavras-chave: estudo numérico, tanque de agitação, fluido pseudoplástico, disco turbina, localização do rotor, a curvatura da lâmina.

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“…Firstly, it seems necessary to validate the CFD computer code; for this task, we have reffered to the review of Mishra et al (1998) and we have realized the same geometrical parameters.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Effect Of the Curvature Bladementioning

confidence: 99%

See 1 more Smart Citation

<b>Numerical investigation of flow induced by a disc turbine in unbaffled stirred tank</b> - doi: 10.4025/actascitechnol.v35i3.15554

Ameur

Bouzit

2013

Acta Sci. Technol.

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“…Sedahmed et al El-Shazly et al, 2004) used a suspension of poly(ethylene oxide) particles in a stirred vessel and found that drag-reducing solid polymers reduced the rate of diffusion-controlled corrosion; these results were consistent with their previous results about the reduction of mass transfer by DRAs. Mishra et al (1998) investigated the effect of PAM on flow patterns in a vessel stirred with a Rushton turbine, for three different DRA concentrations; they presented the results in the form of velocity profile plots, showing the magnitude of the mean and r.m.s. velocity values at various positions in the stirred vessel as a function of the PAM concentration.…”

Section: Drag Reduction and Stirred Vesselsmentioning

confidence: 99%

“…At the edge of the jet, where usually one finds the liquid being entrained into the recirculation loops, the results become less consistent: while an addition of 2000 or 10,000 ppm of PAM leads to a decrease of U * * PAM and even to flow reversal, the intermediate PAM concentration of 5000 ppm increases the value of U * * PAM . Mishra et al (1998) calculated the Reynolds number for each of the three PAM used in their experiments. The presence of the polymer, especially in these rather elevated concentrations, evidently increased the apparent viscosity of the liquid; laser Doppler velocity measurements (e.g., by Mavros et al, 1996) have already showed that a viscosity increase may lead to flow pattern disruptions.…”

Section: Drag Reduction and Stirred Vesselsmentioning

confidence: 99%

A study of the effect of drag-reducing surfactants on flow patterns in stirred vessels

Mavros

Ricard

Xuereb

et al. 2011

Chemical Engineering Research and Design

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CFD simulation of stirred tanks: Comparison of turbulence models. Part I: Radial flow impellers

et al. 2011

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A critical review of the published literature regarding the computational fluid dynamics (CFD) modelling of single-phase turbulent flow in stirred tank reactors is presented. In this part of review, CFD simulations of radial flow impellers (mainly disc turbine (DT)) in a fully baffled vessel operating in a turbulent regime have been presented. Simulated results obtained with different impeller modelling approaches (impeller boundary condition, multiple reference frame, computational snap shot and the sliding mesh approaches) and different turbulence models (standard k − ε model, RNG k − ε model, the Reynolds stress model (RSM) and large eddy simulation) have been compared with the in-house laser Doppler anemometry (LDA) experimental data. In addition, recently proposed modifications to the standard k − ε models were also evaluated. The model predictions (of all the mean velocities, turbulent kinetic energy and its dissipation rate) have been compared with the experimental measurements at various locations in the tank. A discussion is presented to highlight strengths and weaknesses of currently used CFD models. A preliminary analysis of sensitivity of modelling assumptions in the k − ε models and RSM has been carried out using LES database. The quantitative comparison of exact and modelled turbulence production, transport and dissipation terms has highlighted the reasons behind the partial success of various modifications of standard k − ε model as well as RSM. The volume integral of predicted energy dissipation rate is compared with the energy input rate. Based on these results, suggestions have been made for the future work in this area.Nous présentons un examen critique de la littérature concernant la modélisation de la dynamique des fluides numérique (DFN) de l'écoulement turbulentà une phase dans les réacteursà cuve agitée. Dans cette partie de l'examen, nous présentons les simulations de DFN de turbinesà ecoulement radial (principalement des turbinesà disque (TD)) dans un réservoir entièrement cloisonné effectuées dans un régime turbulent. Les résultats des simulations obtenus grâceà différentes approches de modélisation des turbines (couche limite turbulente, méthode des référentiels multiples, snap-shot de modélisation numérique, maillage glissant) età différents modèles de turbulence (modèle standard k-e, modèle RNG k-e, modèle aux tensions de Reynolds et simulation des grandeséchelles) ontété comparés aux données expérimentales internes d'allocation de Dirichlet latente (ADL). De plus, les modifications des modèles standards k-e récemment proposées ontégalementétéévaluées. Les prédictions du modèle (de toutes les vitesses moyennes, de l'énergie cinétique turbulente et de son taux de dissipation) ontété comparées aux données expérimentales relevéesà différents endroits de la cuve. Une discussion présente les points forts et les points faibles des modèles de DFN actuellement utilisés. Une analyse préliminaire de la sensibilité des hypothèses de modélisation liées aux modèles k-e et RSM aété menée en utilis...

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Flow generated by a disc turbine in aqueous solutions of polyacrylamide

Cited by 12 publications

References 6 publications

<b>Numerical investigation of flow induced by a disc turbine in unbaffled stirred tank</b> - doi: 10.4025/actascitechnol.v35i3.15554

<b>Numerical investigation of flow induced by a disc turbine in unbaffled stirred tank</b> - doi: 10.4025/actascitechnol.v35i3.15554

A study of the effect of drag-reducing surfactants on flow patterns in stirred vessels

CFD simulation of stirred tanks: Comparison of turbulence models. Part I: Radial flow impellers

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