化工学报 ›› 2015, Vol. 66 ›› Issue (3): 896-904.DOI: 10.11949/j.issn.0438-1157.20141058

• 流体力学与传递现象 • 上一篇    下一篇

双层刚柔组合搅拌桨调控流体宏观不稳定性行为

朱俊1, 刘作华1,2, 郑雄攀1, 陈超1, 王运东2   

  1. 1 重庆大学化学化工学院, 重庆 400044;
    2 清华大学化学工程系, 北京 100084
  • 收稿日期:2014-07-14 修回日期:2014-11-05 出版日期:2015-03-05 发布日期:2015-03-05
  • 通讯作者: 刘作华
  • 基金资助:

    国家重点基础研究发展计划项目(2012CBA01203);清华大学化学工程联合国家重点实验室开放课题(SKL-ChE-12A02);重庆市自然科学基金重点项目(CSTC2012JJB0006)。

Macro-instability regulated by double rigid-flexible combination impeller

ZHU Jun1, LIU Zuohua1,2, ZHENG Xiongpan1, CHEN Chao1, WANG Yundong2   

  1. 1 School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China;
    2 Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
  • Received:2014-07-14 Revised:2014-11-05 Online:2015-03-05 Published:2015-03-05
  • Supported by:

    supported by the National Basic Research Program of China (2012CBA01203), the State Key Laboratory of Chemical Engineering (SKL-ChE-12A02) and the Key Natural Science Fund of Chongqing (CSTC2012JJB0006).

摘要:

流体宏观不稳定性是搅拌槽内流体流动存在大尺度低频非稳态准周期现象,可以影响流体的能量﹑质量的传递行为。为揭示在双层组合桨作用下搅拌槽内流体的非稳态流动规律,实验采用频谱分析和流场可视化技术研究双层组合桨搅拌槽内自来水体系的宏观不稳定性,对比分析了双层刚性桨和双层组合桨对流体混合的影响。结果表明:直径为T的搅拌槽内流体宏观不稳定频率与转速呈线性增大趋势,在转速为180 r·min-1时离底距离 0.25T刚柔组合桨体系的宏观不稳定性频率消失,出现谱带现象,流场呈现多尺度结构特征,而离底距离为0.33T和0.5T的刚柔组合桨体系的宏观不稳定性频率分别为0.5096 Hz和0.3459 Hz。双层组合桨体系分别使流体的混合时间缩短了22.5%和35%左右,减小离底距离,可使流场的规则区减小。双层刚柔组合桨调控流体宏观不稳定性,强化流体的能量传递行为,从而缩短混合时间,提高了流体的混合效率。

关键词: 混合, 搅拌容器, 传递, 宏观不稳定性, 流场可视化, 双层刚柔组合桨

Abstract:

Fluid macro-instability is a large scale low frequency transient quasi-periodic phenomenon existing in stirred vessel, and affects fluid energy and mass transfer behavior. To reveal the nature of unsteady flow in a stirred vessel with double rigid-flexible impeller, tap water was used as working fluid, and wavelet analysis and flow field visualization were adopted to analyze the influence of double rigid-flexible impeller on the frequency of macro-instability. The difference between double rigid and double rigid-flexible impellers was analyzed in terms of mixing performance. The frequency of macro-instability increased linearly with agitation speed. At agitation speed 180 r·min-1, macro-instability frequency values of rigid-flexible impeller were 0.5096 Hz and 0.3459 Hz with off-bottom clearance 0.33T and 0.5T, respectively. Compared with double rigid impeller system, mixing time was shortened by about 22.5% and 35%, respectively. But macro-instability with off-bottom clearance 0.25T disappeared and bands phenomenon appeared. Shortening the off-bottom clearance could reduce the regular area. Double rigid-flexible combination impeller regulated fluid macro-instability and strengthened energy transfer behavior, so as to shorten mixing time and improve mixing efficiency of the fluid.

Key words: mixing, stirred vessel, transfer, macro-instability, flow field visualization, double rigid-flexible impeller

中图分类号: