Laser-Doppler measurements of turbulent-flow parameters in a stirred mixer

Wu, Hao; Patterson, G. K.

doi:10.1016/0009-2509(89)85155-3

Cited by 447 publications

(348 citation statements)

References 26 publications

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“…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%

“…The calculation of  has been the subject of many previous works (e.g. 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.…”

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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

PIV study of the flow field generated by a sawtooth impeller

Unadkat

Rielly

Nagy

2011

Chemical Engineering Science

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“…Therefore, before any investigation, it is necessary to check the validity of the numerical method used. For this purpose, a comparison is made between our predicted results and the experimental data given by Wu and Patterson (1989). We note that the same geometrical conditions as those undertaken by Wu and Patterson were considered.…”

Section: Resultsmentioning

confidence: 87%

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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“…• Kinetic energy balance term averaged over a control volume [21][22][23] • Integration of dissipation spectrum [24,25] • Dimensional analysis [26] In the present work, of surface aeration systems has been calculated by using commercial software Visimix [18]. The Visimix [18] program can be helpful in analyzing the mixing parameters in a stirred tanks [27,28].…”

Section: Dissipation Rate Of Turbulent Kinetic Energy εmentioning

confidence: 99%

Energy Dissipation and Shear Rate with Geometry of Baffled Surface Aerator

Kumar

2010

Chem. Eng. Res. Bull.

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Abstract:The geometric parameters of surface aeration systems govern the process phenomena. The dissipation rate of turbulent kinetic energy (ε) and shear rate (γ) are the key process parameters for mixing in surface aerators. Present work by doing numerical computation by visimix analyzes the effect of geometric parameters (impeller diameter, cross-sectional area of the tank, liquid height, width of the baffle, rotor blade length and immersion height) on ε and γ . Analysis has been done by making the geometric parameters non-dimensionalized through rotor diameter. With an increase in liquid height and baffled width, there is an increase in the case of energy dissipation and shear rate values. In the case of tank area and blade length, it is vice versa. Energy dissipation and shear rate are not affected by the variation in immersion height of the impeller.

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Laser-Doppler measurements of turbulent-flow parameters in a stirred mixer

Cited by 447 publications

References 26 publications

PIV study of the flow field generated by a sawtooth impeller

PIV study of the flow field generated by a sawtooth impeller

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

Energy Dissipation and Shear Rate with Geometry of Baffled Surface Aerator

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