Hydrodynamic Performance of a Ring‐Style High‐Shear Impeller in Newtonian and Shear‐Thinning Fluids

Guadarrama-Pérez, R.; Márquez-Baños, Valaur E.; Concha-Gómez, Aarón D. De La; Valencia-López, José J.; Vengoechea-Pimienta, Alejandra; Jesús, Gastón Martínez de; Ramírez-Muńoz, J.

doi:10.1002/ceat.201900569

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…A few studies have covered the underlying mixing dynamics within an unbaffled stirred vessel (Busciglio, Grisafi, Scargiali, & Brucato, 2014). Some of them are devoted to the laminar regime (Guadarrama-Pérez et al, 2020;Lamberto, Alvarez, & Muzzio, 1999) and a few more deal with the turbulence regime (Glover & Fitzpatrick, 2007;Li, Wang, Feng, & Gu, 2017;Li, Xiang, & Xiang, 2020;Martínez-de Jesús, Ramírez-Muñoz, García-Cortés, & Cota, 2018). For instance, Li et al (2017) coupled a volume-of-fluid method to a Reynolds stress model to capture the gas-liquid interface and turbulent flow agitated by pitched blade turbines where the interface deflection reached the impeller hub.…”

Section: Introductionmentioning

confidence: 99%

The transition to aeration in turbulent two-phase mixing in stirred vessels

Kahouadji

Liang

Valdés

et al. 2022

Flow

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We consider the mixing dynamics of an air–liquid system driven by the rotation of a pitched blade turbine (PBT) inside an open, cylindrical tank. To examine the flow and interfacial dynamics, we use a highly parallelised implementation of a hybrid front-tracking/level-set method that employs a domain-decomposition parallelisation strategy. Our numerical technique is designed to capture faithfully complex interfacial deformation, and changes of topology, including interface rupture and dispersed phase coalescence. As shown via transient, a three-dimensional (3-D) LES (large eddy simulation) using a Smagorinsky–Lilly turbulence model, the impeller induces the formation of primary vortices that arise in many idealised rotating flows as well as several secondary vortical structures resembling Kelvin–Helmholtz, vortex breakdown, blade tip vortices and end-wall corner vortices. As the rotation rate increases, a transition to ‘aeration’ is observed when the interface reaches the rotating blades leading to the entrainment of air bubbles into the viscous fluid and the creation of a bubbly, rotating, free surface flow. The mechanisms underlying the aeration transition are probed as are the routes leading to it, which are shown to exhibit a strong dependence on flow history.

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Section: Introductionmentioning

confidence: 99%

The transition to aeration in turbulent two-phase mixing in stirred vessels

Kahouadji

Liang

Valdés

et al. 2022

Flow

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“…Lower values have been suggested for mixed flow impellers, − and 3 times higher values have been recently obtained in the transitional regime from 2D-PIV data in a baffled vessel stirred by a pitched blade turbine . A value close to 12 was also obtained in an unbaffled vessel stirred with a high shear impeller …”

Section: Methodsmentioning

confidence: 67%

“…29 A value close to 12 was also obtained in an unbaffled vessel stirred with a high shear impeller. 30 The viscosity curves of the three solutions at 18 °C are reported as a function of the shear rate in Figure 3. Given the uncertainties in the value of K, the range of shear rates calculated by eq 4 adopting three different values of K (K = 11 and 11 ± 10%) at the three values of N adopted in the PIV experiments are marked with red rectangles.…”

Section: Rheological Characterization Of the Mimic Process Fluidsmentioning

confidence: 99%

Power Consumption and Fluid Mixing in a Scale-Down Geometry of a Stirred Digester for Biogas Production

et al. 2023

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A unconventional stirred tank of geometry typically adopted for the production of biogas is experimentally investigated with pseudo-plastic model fluids. The apparent viscosities of the fluids, based on the Metzner–Otto method, are in the range of 39–264 mPa·s, resulting in a range of rotational Reynolds number equal to 17–648. The power consumption of the three top-entering agitators is measured by a strain gauge technique, and the power number curve is obtained in the full range of flow regimes, going from laminar to fully turbulent conditions. The flow field measured by particle image velocimetry allows us to observe the fluid circulation patterns and their variations in different operative conditions. The measurements reveal relatively low axial and radial velocities, especially toward the bottom of the tank, that may hinder solid feedstock suspension and subsequent biogas production. Significant changes in the flow patterns are observed with small variations in the impeller speed and the mixture viscosity. The homogenization dynamics of a tracer obtained by planar laser-induced fluorescence leads us to estimate the dimensionless mixing time, a trend similar to that observed for conventional stirred vessel geometries. The detailed fluid dynamics information collected by a combination of different techniques can contribute to optimize the energy requirement and to avoid failure of the biogas production due to poor fluid mixing.

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“…Only a few applications of CFD to unbaffled stirred tanks are available in the literature (Trad et al, 2017;Li et al, 2017;Martínez-de Jesús et al, 2018;Li et al, 2020). Some of them are specifically devoted to the laminar regime where unbaffled tanks are largely used (Lamberto et al, 1999;Márquez-Baños et al, 2019;Guadarrama-Pérez et al, 2020), especially when non-Newtonian fluids are employed (Márquez-Baños et al, 2019;Guadarrama-Pérez et al, 2020). Others deal also with the turbulent regime (Glover and Fitzpatrick, 2007;Davoody et al, 2019).…”

Section: Introductionmentioning

confidence: 99%