Large eddy simulation of a pitched blade impeller mixed vessel – Comparison with LDA measurements

Vlček, Petr; Kysela, Bohuš; Jirout, Tomáš; Fořt, Ivan

doi:10.1016/j.cherd.2016.02.020

Cited by 13 publications

(10 citation statements)

References 23 publications

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“…50 %) is visible within the range z/H = 0.25 − 0.5 where we have a clearly smoother distribution of experimental data. Vlček et al [23] studied velocity fields in a vessel agitated by the 6PBT45 impeller using LDA experiments and LES-based simulations in ANSYS CFD software.…”

Section: Resultsmentioning

confidence: 99%

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Application of the Temperature Oscillation Method in Heat Transfer Measurements at the Wall of an Agitated Vessel

et al. 2018

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Abstract. The Temperature Oscillation Infra-Red Thermography (TOIRT) was used to measure convective heat transfer coefficients at the inner vertical wall of an agitated and baffled vessel. Two impellers were used: an axial six-blade impeller with pitched blades and the Rushton turbine. The TOIRT method represents an indirect method based on measuring the phase shift between the oscillating heat flux applied to one side of the heat transfer surface and the wall temperature response monitored by a contactless infra-red camera at the same side. On the basis of this phase shift, the TOIRT method can indirectly evaluate the heat transfer coefficient on the other side of the heat transfer surface. Two forms of experimental results are presented in this paper. The first one describes graphical dependencies of the local Nusselt number on the dimensionless distance from the vessel bottom for various Reynolds numbers. The second form describes the mean Nusselt number along the wall as a function of the Reynolds number.

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Section: Resultsmentioning

confidence: 99%

“…Rushton turbine 8.75 ± 33 % 0.336 ± 9.5 % 6PBT45 5.98 ± 34 % 0.328 ± 9.6 % (23) it is possible to calculate the Nusselt number as 395. Using (6) and rotation speed N = 300 min −1 , the Reynolds number in the agitated vessel Re M is 50 000.…”

Section: Mmentioning

confidence: 99%

Application of the Temperature Oscillation Method in Heat Transfer Measurements at the Wall of an Agitated Vessel

et al. 2018

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“…In this work, the Large Eddy Simulation (LES) approach using the Dynamic Smagorinsky‐Lilly (DSL) model is chosen for turbulence modeling, which has been used widely for turbulence modeling in stirred tanks . In the LES model, the large‐scale vortices are spatially filtered and computed explicitly by solving the Navier‐Stokes equations directly, whereas the small‐scale vortices are solved by subgrid scale (SGS) models.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Numerical and experimental investigation on surface air entrainment mechanisms of a novel long‐short blades agitator

et al. 2017

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We investigate numerically and experimentally the mechanisms of surface air entrainment in the vessels equipped with the long‐short blades agitator. VOF method coupled with LES model is used to visualize the surface air entrainment process. In the case of partial submergence of the long blades (LBs), the interaction of the LBs with the liquid free surface creates a depression behind the LBs. Backfilling of the liquid into the depression leads to gas separation and entrapping into the liquid. The critical tip velocity of the LBs, utip,c, for the onset of gas entrainment is measured in vessels with diameters, T = 200∼600 mm. It is found that when H/T ≥ 1.0, utip,c is determined by the LBs, independent of the liquid level. utip,c is also affected by the size of the vessel through the diameter of the sweeping circle of the LBs, but for substantially large vessels, it approaches a constant value. © 2017 American Institute of Chemical Engineers AIChE J, 63: 316–325, 2018

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“…The computational fluid dynamics (CFD) simulation is used to promote the study of the fundamental phenomena, which could provide the flow field information in the stirred tank [18]. As we know, the large eddy simulation (LES) could obtain the precision flow field information, and its computational consumption is between the direct numerical simulation (DNS) and the Reynolds-averaged Navier-Stokes equations (RANS) [19]. Large eddy simulation was first applied in the simulation of stirred tanks by Eggles and was proven to be a good method to study turbulent flows [20].…”

Section: Introductionmentioning

confidence: 99%

The Process of the Intensification of Coal Fly Ash Flotation Using a Stirred Tank

Zhu

et al. 2018

Minerals

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Pulp preconditioning using a stirred tank as a pretreatment process is vital to the flotation system, which can be used to improve the flotation efficiency of mineral particles. The kinetic energy that is dissipated in the stirred tank could strengthen the interaction process between mineral particles and flotation reagents to improve the flotation efficiency in the presence of the preconditioning. In this paper, the effect of the conditioning speed on the coal fly ash flotation was investigated using numerical simulations and conditioning-flotation tests. The large eddy simulation coupled with the Smagorinsky-Lilly subgrid model was employed to simulate the turbulence flow field in the stirred tank, which was equipped with a six blade Rushton turbine. The impeller rotation was modelled using the sliding mesh. The simulation results showed that the large eddy simulation (LES) well matched the previous experimental data. The turbulence characteristics, such as the mean velocity, turbulent kinetic energy, power consumption and instantaneous structures of trailing vortices were analysed in detail. The turbulent length scale (η) decreased as the rotation speed increased, and the minimum value of η was almost unchanged when the rotation speed was more than 1200 rpm. The conditioning-flotation tests of coal fly ash were conducted using different conditioning speeds. The results showed that the removal of unburned carbon was greatly improved due to the strengthened turbulence in the stirred tank, and the optimal results were obtained with an LOI of 3.32%, a yield of 78.69% and an RUC of 80.89% when the conditioning speed was 1200 rpm.

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Large eddy simulation of a pitched blade impeller mixed vessel – Comparison with LDA measurements

Cited by 13 publications

References 23 publications

Application of the Temperature Oscillation Method in Heat Transfer Measurements at the Wall of an Agitated Vessel

Application of the Temperature Oscillation Method in Heat Transfer Measurements at the Wall of an Agitated Vessel

Numerical and experimental investigation on surface air entrainment mechanisms of a novel long‐short blades agitator

The Process of the Intensification of Coal Fly Ash Flotation Using a Stirred Tank

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