Numerical evaluation of turbulent flow structures in a stirred tank with a Rushton turbine based on scale-adaptive simulation

Zamiri, Ali; Chung, Jin Taek

doi:10.1016/j.compfluid.2018.05.007

Cited by 20 publications

(9 citation statements)

References 33 publications

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“…In this paper, the Gidaspow drag coefficient model is used, which is suitable for the solid-liquid flow field with high solid holdup. 17–19 The Wen-Yu model is employed when the solid content of the flow field is lower than 20%, and the equation form is as follows: The Ergun model is used when the solid content of the flow field is higher than 20%, and the equation form is as follows: where normaldnormals is the particle diameter; normalunormals and normalunormall are the velocity vectors of the solid and liquid fluids respectively; αnormals and αnormall are the volume fractions of the solid and liquid fluids respectively; ρnormall is the density of the liquid; μnormall is the viscosity of the liquid.…”

Section: Cfd Calculation Modelmentioning

confidence: 99%

Numerical analysis and optimization of key parts in the stirred tank based on solid-liquid flow field

Jiang

Yuan

et al. 2022

Science Progress

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In order to further improve the mixing performance of the mixing device, the structure of the agitator was optimized, and the effects of the diameter and pitch of the agitator on the solid-liquid suspension characteristics were analyzed by single factor method. Multiple reference frame (MRF), computational fluid dynamics, Euler multiphase flow model and standard K- ε turbulence model were used to investigate the effect of the height from the bottom of the agitator on the suspension characteristics of particles in the agitator was studied. The results show that reducing the height from the bottom of the agitator can promote the suspension of particles at the bottom of the tank, but too low height from the bottom will easily produce mixing dead zone at the bottom of the tank, and cause the accumulation of particles. Reducing the height of the agitator from the bottom will enlarge the clear liquid area of the flow field, cause uneven particle distribution and increase the stirring torque. With the increase of agitator diameter, the critical suspension speed of the flow field decrease, but the stirring power required by the flow field increase. Increasing the blade spacing in a certain range can promote the suspension of particles and make the distribution of particles in the flow field more uniform. Therefore, the mixing power and the uniformity of particle concentration distribution need to be considered together in order to make the mixing device more efficient and energy-saving.

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Section: Cfd Calculation Modelmentioning

confidence: 99%

Numerical analysis and optimization of key parts in the stirred tank based on solid-liquid flow field

Jiang

Yuan

et al. 2022

Science Progress

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“…Different flow patterns could influence the contact area, mass transfer, and chemical reaction rate of the gas–liquid two-phase, and so on. − As a result, flow pattern identification is of great significance for deeply understanding the comprehensive characteristics of gas–liquid two-phase flow. In recent years, comprehensive research on the pressure fluctuation characteristics of the gas–liquid two-phase in a variety of reactors such as a bubble column, , fluidized bed, − stirred tank, , and static mixer − has been conducted by many scholars. Letzel et al characterized the chaotic characteristics of the fluid in the bubble column by PFS, and the fluid transition from a uniform flow state to a nonuniform flow state could be found quantitatively.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Turbulence Characteristics of Gas–Liquid Pressure Fluctuations in an Industrial Quatro Static Mixer

Yu,

Li,

Meng

et al. 2024

Ind. Eng. Chem. Res.

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The gas−liquid two-phase flow is of great significance to industrial production. The nonlinear turbulence characteristics of pressure fluctuation in a Quatro static mixer (QSM) are experimentally investigated under different superficial gas/liquid velocities to further study the flow characteristics of the gas−liquid two-phase. It is shown that there is a generalized self-similarity scaling law in the QSM, which is obtained by fitting the structure function of pressure fluctuation signals at different inlet and outlet flow velocities. Through self-similarity scaling law analysis, the scaling exponent parameters of the structure function of two-phase flow pressure fluctuation under apparent liquid velocity (U L ) = 0.028 m/s and different apparent gas velocities (U G ) in QSM are calculated. The calculation results show that the singular scaling exponent (γ) and intermittency parameter (β) are in the ranges of −0.142−0.311 and 0.286−0.966, respectively. This indicates that there exists an extended self-similarity scaling law in QSM under a low Reynolds number (Re). The R/S and autocorrelation analysis reveal that the detailed signals at the inlet and outlet have three similar flow behaviors, which consist of the liquid turbulence at the inlet, the bubble movement, breakup and coalescence, and the liquid swirling flow. The nonlinear analysis shows that flow in QSM presents a pseudohomogeneous flow pattern when the Hurst index (H) = 0.4−0.6, while it presents a heterogeneous flow pattern when H = 0.6−0.72. Support vector machine (SVM) and Random Forest models (RF) are utilized to better predict the flow pattern, with the recognition precision reaching 99.08 and 99.39%, respectively.

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“…This is an extensive work about turbulence behavior modeled by three different models. Moreover, the SAS‐SST turbulence model mean flow distributions are shown in Reference 9. Additionally, spectral analysis of pressure fluctuations was performed to show them as the main source of the flow instability.…”

Section: Introductionmentioning

confidence: 99%

Modeling mixing dynamics in uncovered baffled and unbaffled stirred tanks

et al. 2021

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This paper presents results of measurements performed in uncovered baffled and unbaffled stirred tanks. The Laser Doppler Anemometry (LDA) set consists of a 300 mW argon‐ion laser generating two pairs of blue and green beams. Additionally, three turbulence models are verified to simulate mixing dynamics in uncovered baffled and unbaffled stirred tanks. Simulations are performed using both the steady‐ and the transient‐state approach. The unbaffled tank was modeled using both the single‐ and the multiphase approaches. The cited correlations of the central vortex depth are used to verify the multiphase calculations. In order to reduce the computational time, a simplified numerical model is proposed. It assumes a single‐phase simulation without the central vortex. The flow fields below the central vortex level are compared between the single‐ and the multiphase approach. The simplified model can be used both to design and optimize the mixing process.

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Numerical evaluation of turbulent flow structures in a stirred tank with a Rushton turbine based on scale-adaptive simulation

Cited by 20 publications

References 33 publications

Numerical analysis and optimization of key parts in the stirred tank based on solid-liquid flow field

Numerical analysis and optimization of key parts in the stirred tank based on solid-liquid flow field

Multiscale Turbulence Characteristics of Gas–Liquid Pressure Fluctuations in an Industrial Quatro Static Mixer

Modeling mixing dynamics in uncovered baffled and unbaffled stirred tanks

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