Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller

doi:10.1016/j.cjche.2021.11.010

中国化学工程学报 ›› 2022, Vol. 45 ›› Issue (5): 143-152.DOI: 10.1016/j.cjche.2021.11.010

Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller

Yongjun Wu, Pan You, Peicheng Luo

School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China

收稿日期:2021-07-21 修回日期:2021-11-18 出版日期:2022-05-28 发布日期:2022-06-22
通讯作者: Peicheng Luo,E-mail:luopeicheng@seu.edu.cn
基金资助:
We acknowledge the financial support from the National Natural Science Foundation of China (22078058). We also thank the Big Data Center of Southeast University for providing the facility support on the numerical simulations in this work.

Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller

Yongjun Wu, Pan You, Peicheng Luo

School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China

Received:2021-07-21 Revised:2021-11-18 Online:2022-05-28 Published:2022-06-22
Contact: Peicheng Luo,E-mail:luopeicheng@seu.edu.cn
Supported by:
We acknowledge the financial support from the National Natural Science Foundation of China (22078058). We also thank the Big Data Center of Southeast University for providing the facility support on the numerical simulations in this work.

摘要/Abstract

摘要： This work focuses on the design improvement of the long-short blades (LSB) impeller by using pitched short blades (SBs) to regulate the flow field in the stirred vessel. After mesh size evaluation and velocity field validation by the particle image velocimetry, large eddy simulation method coupled with sliding mesh approach was used to study the effect of the pitched SBs on the flow characteristics. We changed the inclined angles of the SBs from 30° to 60° and compared the flow characteristics when the impeller was operated in the down-pumping and up-pumping modes. In the case of down-pumping mode, the power number is relatively smaller and vortexes below the SBs are suppressed, leading to turbulence intensification in the bottom of the vessel. Whereas in the case of up-pumping mode, the axial flow rate in the center increased significantly with bigger power number, resulting in more efficient mass exchange between the axial and radial flows in the whole vessel. The LSB with 45° inclined angle of the SBs in the up-pumping mode has the most uniform distributions of flow field and turbulent kinetic energy compared with other impeller configurations.

关键词: Stirred tank, Computational fluid dynamics (CFD), Turbulent flow, Long-short blades (LSB) impeller, Pitched blades

Abstract: This work focuses on the design improvement of the long-short blades (LSB) impeller by using pitched short blades (SBs) to regulate the flow field in the stirred vessel. After mesh size evaluation and velocity field validation by the particle image velocimetry, large eddy simulation method coupled with sliding mesh approach was used to study the effect of the pitched SBs on the flow characteristics. We changed the inclined angles of the SBs from 30° to 60° and compared the flow characteristics when the impeller was operated in the down-pumping and up-pumping modes. In the case of down-pumping mode, the power number is relatively smaller and vortexes below the SBs are suppressed, leading to turbulence intensification in the bottom of the vessel. Whereas in the case of up-pumping mode, the axial flow rate in the center increased significantly with bigger power number, resulting in more efficient mass exchange between the axial and radial flows in the whole vessel. The LSB with 45° inclined angle of the SBs in the up-pumping mode has the most uniform distributions of flow field and turbulent kinetic energy compared with other impeller configurations.

Key words: Stirred tank, Computational fluid dynamics (CFD), Turbulent flow, Long-short blades (LSB) impeller, Pitched blades

Yongjun Wu, Pan You, Peicheng Luo. Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller[J]. 中国化学工程学报, 2022, 45(5): 143-152.

Yongjun Wu, Pan You, Peicheng Luo. Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller[J]. Chinese Journal of Chemical Engineering, 2022, 45(5): 143-152.

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Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller

Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller

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