Use of angle resolved PIV to estimate local specific energy dissipation rates for up- and down-pumping pitched blade agitators in a stirred tank

Gabriele, A.; Nienow, Alvin W.; Simmons, Mark

doi:10.1016/j.ces.2008.09.018

Cited by 115 publications

(94 citation statements)

References 30 publications

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“…Comparisons between the various calculation methods of  have been presented by Unadkat (2010), and are not the focus of the current paper. The conclusion that the large eddy analogy of Sheng et al (2000) is a useful method to calculate  , is in agreement with the works of Khan (2005) and Gabriele et al (2009).…”

Section: Dissipation Ratesupporting

confidence: 91%

“…Compared to Rushton disk turbines (RDTs) and pitched-blade turbines (PBTs), which have received a lot of attention over the last three decades (e.g. van"t Riet and Smith, 1975;Wu and Patterson, 1989;Lee and Yianneskis, 1998;Yianneskis and Whitelaw, 1993;Khan et al, 2004;Gabriele et al, 2009), the hydrodynamics of sawtooth impellers are relatively unknown, and have not been widely investigated. Consequently, a study has been carried out to investigate the flow field and turbulence properties generated by an EkatoMizer, which is a type of sawtooth impeller.…”

Section: Introductionmentioning

confidence: 99%

“…Kresta and Wood, 1993;Wu and Patterson, 1989;Zhou and Kresta, 1996;Baldi and Yianneskis, 2003;Ducci and Yianneskis, 2005;Sharp and Adrian, 2001;Khan, 2005, Kilander andRasmuson, 2005;Sheng et al, 2000); a comparison between the different methods has not been provided in this paper (but may be found in the work of Unadkat (2010)). It is now well known that the LES analogy provides the best approximation (Khan, 2005;Gabriele et al, 2009), and hence this method has been employed here to estimate the dissipation rate. This paper also addresses the issue of spurious vectors in raw PIV measurements, which lead to the calculation of erroneous velocity gradients and have a compounding effect on the dissipation rate estimate in the LES analogy method.…”

Section: Introductionmentioning

confidence: 99%

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PIV study of the flow field generated by a sawtooth impeller

Unadkat

Rielly

Nagy

2011

Chemical Engineering Science

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Stereoscopic and high-speed particle image velocimetry (PIV) techniques have been employed to study the flow field induced by a sawtooth (EkatoMizer) impeller, operated in the fully turbulent flow regime at an impeller speed of 1500 rpm.Ensemble-averaged mean flow fields and turbulence quantities were calculated for a region close to the impeller blades. The flow was found to be anisotropic near the impeller and exhibited return-to-isotropy behaviour further away from it. Macroinstabilities were found to have a high probability of occurrence in the discharge stream. All three velocity components from the stereo-PIV measurements were used to estimate the dissipation rate, by adopting a large eddy simulation (LES) analogy.Spurious vectors distorting the dissipation rate calculation were identified, and various standard deviation filters were applied for vector validation. By evaluating the filtered dissipation rate profiles against the multi-fractal intermittency model of Meneveau and Sreenivasan (1991), the global standard deviation filter was found to be the most suitable type. The ratio of the maximum to the mean dissipation rate for the EkatoMizer discharge stream was found to be similar to that reported for Rushton disk turbine and pitched-blade turbine impellers in the literature, raising questions about the reported high-shear advantage of sawtooth impellers.

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Section: Dissipation Ratesupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PIV study of the flow field generated by a sawtooth impeller

Unadkat

Rielly

Nagy

2011

Chemical Engineering Science

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“…Desde la década de los 70, el uso de herramientas computacionales para el desarrollo del análisis del flujo de fluidos y sus fenómenos se ha ido incrementando gracias al mejoramiento de la tecnología computacional y el desarrollo de técnicas numéricas (Shah et al, 2013;Fernández, 2012). La Dinámica de Fluidos Computacional (CFD del inglés Computational Fluid Dynamics) es una herramienta muy útil para analizar en detalle el fenómeno de la turbulencia en tanques agitadores, los cuales son comúnmente usados en procesos industriales (Jaworski y Zakrzewska, 2002;Montante et al, 2001;Gabriele et al, 2009). …”

Section: Introductionunclassified

Estudio del Comportamiento Fluido-Dinámico de un Agitador a Escala Reducida Mediante Simulación Numérica

et al. 2017

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* Autor a quien debe ser dirigida la correspondenciaRecibido Sep. 25, 2016; Aceptado Dic. 9, 2016; Versión final Mar. 10, 2017, Publicado Jun. 2017 Resumen Se presenta el estudio del comportamiento de un agitador con impulsor hidroala (hydrofoil), usado para mezclar agua con partículas polimetálicas en la industria minera, mediante simulación numérica con software de dinámica de fluidos computacional (CFD). La mezcla tiene densidad promedio de 1.623 kg/m 3 , viscosidad aparente de 0.065 kg/m·s y fue modelada como un líquido homogéneo no-newtoniano. En la simulación el problema se resuelve mediante un modelo homogéneo Euler-Euler para flujo bifásico de superficie libre en estado estacionario, utilizando el modelo de turbulencia k-ε. Se obtuvo la curva de potencia, que relaciona el número de potencia (Np) con el número de Reynolds (Re), a partir de la curva de torque del impulsor en función de su velocidad angular entre 200 y 700 rpm. Se encontró que Np converge asintóticamente a 0.32 en régimen turbulento, valor que está en correspondencia con los resultados experimentales obtenidos en el presente estudio y los disponibles en la literatura. Palabras clave: agitador; número de potencia; impulsor hidroala; CFD; mezcladores Study of the Fluid-Dynamic Behavior of a Reduced Scale Stirred Tank through Numerical Simulation AbstractThis paper presents the study of the behavior of a stirred tank with hydrofoil impeller, used to mix water with polymetallic particles in the mining industry, through numerical simulation with CFD software. The mixture has an average density of 1.623 kg / m 3 and an apparent viscosity of 0.065 kg / m-s, and was modeled as a non-newtonian homogeneous liquid. The homogeneous Euler-Euler model for free surface biphasic flow in steady state is solved in the simulation, using the k-ε turbulence model. The power curve, which correlates the power number (Np) with the Reynolds number (Re), was obtained from the torque curve of the impeller versus its angular velocity between 200 and 700 rpm. It was found that Np asymptotically converges to 0.32 in turbulent regime, a value that is in agreement with experimental results obtained in the present study and those available in the literature.

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“…Efficient design of stirred tank reactors requires knowledge of the hydrodynamic behavior of the flows in such apparatuses. To date, many efforts have been made in order to obtain data both by experimental and computational techniques (Bo et al, 2006;Escudie and Line, 2003;Escudie et al, 2004;Gabriele et al, 2009;Galletti et al, 2003;Mavros, 2001;Mahmud et al, 2009;Nikiforaki et al, 2003;Roy et al, 2010;Yeoh et al, 2004;Yoon et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Effect of Some Design Parameters on the Flow Fields and Power Consumption in a Vessel Stirred by a Rushton Turbine

Youcefi¹,

Bouzit²,

Ameur³

et al. 2013

Chemical and Process Engineering

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Knowledge of the fluid dynamic characteristics in a stirred vessel is essential for reliable design and scale-up of a mixing system. In this paper, 3D hydrodynamics in a vessel agitated by a Rushton turbine were numerically studied (with the help of a CFD computer program (CFX 13.0)). The study was carried out covering a wide Reynolds number range: 10 4 -10 5 . Computations, based on control volume method, were made using the k-ε model. Our main purpose was to investigate the effect of vessel configuration and agitation rates on the flow structure and power consumption. Three types of vessels were used: unbaffled, baffled and a vessel with slots placed at the external perimeter of its vertical wall. The effect of slot length has been investigated. The comparison of our predicted results with available experimental data shows a satisfactory agreement.

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Use of angle resolved PIV to estimate local specific energy dissipation rates for up- and down-pumping pitched blade agitators in a stirred tank

Cited by 115 publications

References 30 publications

PIV study of the flow field generated by a sawtooth impeller

PIV study of the flow field generated by a sawtooth impeller

Estudio del Comportamiento Fluido-Dinámico de un Agitador a Escala Reducida Mediante Simulación Numérica

Effect of Some Design Parameters on the Flow Fields and Power Consumption in a Vessel Stirred by a Rushton Turbine

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