Effects of baffle on cycle‐to‐cycle variation in stirred vessel driven by paddle turbine using quadruple proper orthogonal decomposition

Fan, Ying; Sun, Jinhua; Gao, Tiehong; Zhang, Hui; Chen, Wenyi

doi:10.1002/apj.2690

Cited by 2 publications

(2 citation statements)

References 38 publications

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“…The utilization of the open turbine is prevalent in the stirred field of low viscosity media 20,21 . Agitation is conducted in a stirred vessel, and scenarios involving crystallization or solid–liquid dispersion often employ an unbaffled vessel 22–24 .…”

Section: Introductionmentioning

confidence: 99%

“…The utilization of the open turbine is prevalent in the stirred field of low viscosity media. 20,21 Agitation is conducted in a stirred vessel, and scenarios involving crystallization or solid-liquid dispersion often employ an unbaffled vessel. [22][23][24] To understand the flow characteristics of agitation, this study undertakes PIV experimental research of open turbine agitation in an unbaffled vessel, employing four blade deflection angles.…”

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confidence: 99%

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Flow stirred by open turbine: A modal analysis of multiscale flow characteristics

Jin,

Bu,

Fan

et al. 2024

Asia-Pacific J Chem Eng

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The turbulence observed in the stirred tank is a result of the superposition of flows at different scales, each exerting various influences on the operational processes. To understand the flow characteristics associated with stirring, this paper undertakes particle image velocimetry (PIV) experimental research on an unbaffled tank stirred by an open turbine featuring four distinct blade deflection angles. The flow field in the unbaffled tank manifests as a double‐circulation flow pattern; however, it is worth noting that the blade deflection angle exerts a significant impact on the stirring process. Specifically, when the blade deflection angle reached 90°, the flow discharge aligned closely with the radial direction, accompanied by pronounced fluctuations in the high‐velocity region. The Lagrangian coherent structures (LCS) formed were subsequently extracted and subjected to finite‐time Lyapunov exponent (FTLE) analysis. Notably, a more regular wake pattern emerged in proximity to the blade tip, while a larger scale flow structure persisted along the flow direction. To systematically analyze the flow field stirred by the open turbine, modal analysis was employed. By reconstructing the flow field based on the principle of 50% energy content, the decomposition of flows at different scales was achieved. The turbulent kinetic energy (TKE) generated by the various scale flows was subsequently calculated, revealing that the high TKE values primarily originate from the large‐scale flow structure. Conversely, the TKE generated by the small‐scale flow exhibits a uniform distribution across different regions. Notably, in regions characterized by higher velocities, the peak TKE associated with the small‐scale flow also manifests; however, it is significantly smaller in magnitude compared to that generated by the original flow or the large‐scale flow.

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Flow stirred by open turbine: A modal analysis of multiscale flow characteristics

Jin,

Bu,

Fan

et al. 2024

Asia-Pacific J Chem Eng

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Effects of baffle on flow structure and cyclic variation in stirred tanks with Rushton turbine

Fan

Sun

et al. 2022

AIP Advances

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In order to reveal the effect of baffles on flow structure and cyclic variation stirred by Rushton turbines, particle image velocimetry experiments were performed in baffled and unbaffled stirred tanks. In a baffled tank, the peak value of time-averaged velocity obviously increases, the high velocity region enlarges significantly, and the fluctuation of fluid elements near the turbine increases significantly. In the 20° phase plane of the baffled tank, the high swirl strength region slightly enlarges, but the peak of phase-resolved swirl strength is lower. The peak value and high value regions of turbulent kinetic energy are larger in the baffled stirred tank at various phase planes. Using quadruple proper orthogonal decomposition, the flow field is decomposed into a small-scale part, a transition part, a large-scale part, and a mean part with different spatial scales. Adding the baffle, the mean part with largest spatial scale obviously increases (it is favorable for mass transfer at different liquid levels) and the transition part, which mainly includes the random fluctuation of a turbulent cascade, slightly enhances (it is conducive to diffusion). The main influence of cyclic variation for various blade passages is the flow with large-scale, and the standard deviation of time coefficients decreases by 3%–4% for the mean part and the large-scale part by adding the baffle.

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Effects of baffle on cycle‐to‐cycle variation in stirred vessel driven by paddle turbine using quadruple proper orthogonal decomposition

Cited by 2 publications

References 38 publications

Flow stirred by open turbine: A modal analysis of multiscale flow characteristics

Flow stirred by open turbine: A modal analysis of multiscale flow characteristics

Effects of baffle on flow structure and cyclic variation in stirred tanks with Rushton turbine

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