Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

Cabaret, F.; Fradette, Louis; Tanguy, Philippe A.

doi:10.1002/cjce.20103

Cited by 20 publications

(20 citation statements)

References 14 publications

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“…Forward-reverse agitation could be performed in laminar flow [3,8,9] to minimize the effect of isolated mixing regions or other mixing pathologies. In the turbulent flow regime forward-reverse mixing proceeds more uniformly in the vessel [1,[10][11][12][13][14] but the high shear level of the forward-reverse agitation mode could increase mixing time and mixing power.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Woziwodzki

2011

Chem Eng & Technol

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Usually, mixing is carried out in a vessel with four baffles and a single impeller. In some applications, however, the use of a baffled vessel is not recommended. One of the stirring methods used instead is unsteady agitation with forward-reverse rotating impellers. The aim of this work was to characterize the agitation characteristics in a baffled and an unbaffled vessel with a turbine impeller. Mixing time and mixing power were evaluated in relation to the presence of baffles and the frequency of forward-reverse rotation. It was found that the frequency of oscillation does not affect either the mixing time and mixing power values or the drag and added mass coefficients. Power requirements and mixing time were higher compared to the steady mixing conditions in a baffled vessel. The results showed that it is not recommended to use baffles because they have no influence on unsteady mixing.

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Section: Introductionmentioning

confidence: 99%

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Woziwodzki

2011

Chem Eng & Technol

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“…In general, we observed that eccentricity values in the range of E = 0.40–0.47 render flows with practically no segregated areas (globally chaotic flows) with mixing times 95% in the order of 6–8 min at Re < 1. Similarly, in experiments performed in the laminar regime ( Re = 1.5–13.0; using a radial impeller), Cabaret et al (2008) reported the occurrence of practically complete mixing (as evaluated by a similar technique) only in the narrow window of eccentricity values from E > 0.257 to E > 0.56 and 7.5 < Re < 13.0. Indeed, for the lowest Re value where complete mixing was observed ( Re = 7.5), E values in the range of E = 0.39–0.56 were required.…”

Section: Resultsmentioning

confidence: 83%

“…In the laminar regime, concentric tanks agitated with typical axial (Alvarez et al, 2002a), or radial impellers (Alvarez et al, 2005; Cabaret et al, 2008) exhibit extremely impermeable flow separation planes at the impeller height that practically convert the top and bottom sections in independent reactors from the convective point of view (Alvarez et al, 2005; Sánchez‐Cervantes et al, 2006; Zalc et al, 2002). At eccentricity values higher than 0.30, the top–bottom separation is destroyed and therefore, top–bottom circulation is greatly facilitated.…”

Section: Resultsmentioning

confidence: 99%

“…In stirred tanks commonly used in industry and lab applications, the agitation axis is centrally located (concentric). However, the use of eccentrically agitated systems as mixing vessels has recently received research attention (Alvarez et al, 2002a; Ascanio et al, 2002; Cabaret et al, 2008; Galleti and Brunazzi, 2008; Hu et al, 2010; Karcz et al, 2005; Lai and Yang, 2010; Montante et al, 2006; Sánchez‐Cervantes et al, 2006; Szoplik and Karcz, 2008; Takahashi et al, 2011; Yang et al, 2008, 2011; Woziwodzki and Jedrzejczak, 2010), although it has not been documented in the context of biotechnology applications.…”

Section: Introductionmentioning

confidence: 99%

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A simple eccentric stirred tank mini‐bioreactor: Mixing characterization and mammalian cell culture experiments

Bulnes-Abundis

Carrillo-Cocom

Araíz-Hernández

et al. 2012

Biotech & Bioengineering

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In industrial practice, stirred tank bioreactors are the most common mammalian cell culture platform. However, research and screening protocols at the laboratory scale (i.e., 5-100 mL) rely primarily on Petri dishes, culture bottles, or Erlenmeyer flasks. There is a clear need for simple-easy to assemble, easy to use, easy to clean-cell culture mini-bioreactors for lab-scale and/or screening applications. Here, we study the mixing performance and culture adequacy of a 30 mL eccentric stirred tank mini-bioreactor. A detailed mixing characterization of the proposed bioreactor is presented. Laser induced fluorescence (LIF) experiments and computational fluid dynamics (CFD) computations are used to identify the operational conditions required for adequate mixing. Mammalian cell culture experiments were conducted with two different cell models. The specific growth rate and the maximum cell density of Chinese hamster ovary (CHO) cell cultures grown in the mini-bioreactor were comparable to those observed for 6-well culture plates, Erlenmeyer flasks, and 1 L fully instrumented bioreactors. Human hematopoietic stem cells were successfully expanded tenfold in suspension conditions using the eccentric mini-bioreactor system. Our results demonstrate good mixing performance and suggest the practicality and adequacy of the proposed mini-bioreactor.

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“…Similarly to the flow around a rotating disk in a cylindrical casing and the flow around the impeller in a tank, the state of the inner airflow motion around the GyroWheel rotor can be described by the Reynolds number, which is a dimensionless number as shown in (9), where, in fact, the Reynolds number is represented by the ratio of the non-viscous force to the viscous force [29,30]. Meanwhile, the change rate of the air density can be represented by (10), where the spinning angular velocity of the GyroWheel rotor varies under isothermal condition.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Aerodynamic Drag Analysis of 3-DOF Flex-Gimbal GyroWheel System in the Sense of Ground Test

Huo

Feng

Liu

et al. 2016

Sensors

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GyroWheel is an innovative device that combines the actuating capabilities of a control moment gyro with the rate sensing capabilities of a tuned rotor gyro by using a spinning flex-gimbal system. However, in the process of the ground test, the existence of aerodynamic disturbance is inevitable, which hinders the improvement of the specification performance and control accuracy. A vacuum tank test is a possible candidate but is sometimes unrealistic due to the substantial increase in costs and complexity involved. In this paper, the aerodynamic drag problem with respect to the 3-DOF flex-gimbal GyroWheel system is investigated by simulation analysis and experimental verification. Concretely, the angular momentum envelope property of the spinning rotor system is studied and its integral dynamical model is deduced based on the physical configuration of the GyroWheel system with an appropriately defined coordinate system. In the sequel, the fluid numerical model is established and the model geometries are checked with FLUENT software. According to the diversity and time-varying properties of the rotor motions in three-dimensions, the airflow field around the GyroWheel rotor is analyzed by simulation with respect to its varying angular velocity and tilt angle. The IPC-based experimental platform is introduced, and the properties of aerodynamic drag in the ground test condition are obtained through comparing the simulation with experimental results.

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Effect of shaft eccentricity on the laminar mixing performance of a radial impeller

Cited by 20 publications

References 14 publications

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

Unsteady Mixing Characteristics in a Vessel with Forward‐Reverse Rotating Impeller

A simple eccentric stirred tank mini‐bioreactor: Mixing characterization and mammalian cell culture experiments

Aerodynamic Drag Analysis of 3-DOF Flex-Gimbal GyroWheel System in the Sense of Ground Test

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