V3V study and large eddy simulation of turbulence characteristics in a stirred vessel with Rushton turbine impeller

doi:10.11949/j.issn.0438-1157.20170594

Abstract

Abstract:

The volumetric three-component velocimetry (V3V) measurements and the large eddy simulation (LES) were used to study the flow field near the standard Rushton impeller in a stirred vessel. The results of V3V indicate that the Reynolds number has almost no influence on the normalized phase-resolved velocity and TKE when the flow field is absolutely turbulent. The structure and movement law of trailing vortices are discussed by reconstruction of the three-dimensional flow field with V3V. The distributions of radial, axial and tangential velocities in 30℃ross-section behind the impeller were analyzed. The distributions of vortex pair by V3V were in good agreement with these by 2D-PIV (particle image velocimetry), however the vorticity by V3V is about 37.5% larger. LES method was used to simulate flow field in stirred tank with Rushton turbine impeller. The velocity distribution and trailing trajectory of LES results are in good agreement with the 2D-PIV and V3V data. Complete structure of the trailing vortices had been obtained and a vortex, which is similar with trailing vortices, was discovered near the up surface of the impeller.

Key words: V3V, PIV, LES, trailing vortex, Rushton impeller

摘要：

分别用体三维速度测量技术（volumetric three-component velocimetry measurements，V3V）和大涡模拟（large eddy simulation，LES）方法对涡轮桨搅拌槽内流场进行研究，发现在完全湍流状态下，涡轮桨搅拌槽内流场的量纲1相平均速度及湍动能分布同Reynolds数无关。用V3V方法实现了Rushton桨叶附近三维流场的重构；探讨尾涡的三维结构及运动规律；分析了叶片后方30°截面轴向、径向和环向速度沿径向分布规律。用V3V实验结果对比了2D-PIV（particle image velocimetry）数据中的尾涡涡对位置和涡量，涡对位置吻合度较好，但2D-PIV中涡量较V3V小37.5%；通过大涡模拟得到完整的尾涡结构，发现在叶片上边缘后侧存在一个和尾涡形成方式相同但不成对出现的涡结构；将大涡模拟结果和2D-PIV及V3V实验结果对比发现，大涡模拟在速度分布及尾涡运动轨迹方面均同实验结果吻合较好，表明大涡模拟能较好地预测涡轮桨搅拌槽内流场。

关键词: V3V, PIV, 大涡模拟, 尾涡, 涡轮桨

CLC Number:

TQ022

SHI Naijin, ZHOU Yongjun, BAO Suyang, XIN Wei, TAO Lanlan. V3V study and large eddy simulation of turbulence characteristics in a stirred vessel with Rushton turbine impeller[J]. CIESC Journal, 2017, 68(11): 4069-4078.

施乃进, 周勇军, 鲍苏洋, 辛伟, 陶兰兰. 涡轮桨搅拌槽内湍流特性的V3V实验及大涡模拟[J]. 化工学报, 2017, 68(11): 4069-4078.

References 26

[1]	刘敏珊, 张丽娜, 董其伍. 涡轮桨搅拌槽内混合特性模拟研究[J]. 工程热物理学报, 2009, 30(10):1700-1702. LIU M S, ZHANG L N, DONG Q W. Numerical research of mixing characteristics in a stirred tank with turbine impellers[J]. Journal of Engineering Thermophysics, 2009, 30(10):1700-1702.
[2]	周国忠, 王英琛, 施力田. 用CFD研究搅拌槽内的混合过程[J]. 化工学报, 2003, 54(7):886-890. ZHOU G Z, WANG Y C, SHI L T. CFD study of mixing process in stirred tank[J]. Journal of Chemical Industry and Engineering (China), 2003, 54(7):886-890.
[3]	蔡清白, 戴干策. 翼型桨叶片尾涡结构的PIV实测与LES模拟研究[J]. 过程工程学报, 2011, (4):541-548. CAI Q B, DAI G C. Measurement of trailing vortices around a hydrofoil impeller with PIV and large eddy simulation[J]. The Chinese Journal of Process Engineering, 2011, (4):541-548.
[4]	SHARP K V, ADRIAN R J. PIV study of small-scale flow structure around a Rushton turbine[J]. AIChE Journal, 2001, 47(4):766-778.
[5]	程先明, 李志鹏, 高正明, 等. 涡轮桨搅拌槽内流动及尾涡特性研究[J]. 北京化工大学学报(自然科学版), 2009, 36(6):16-21. CHENG X M, LI Z P, GAO Z M, et al. Characteristics of flow fields and trailing vortices in a stirred tank with a Rushton turbine[J]. Journal of Beijing University of Chemical Technology(Natural Science), 2009, 36(6):16-21.
[6]	CHARA Z, KYSELA B, KONFRST J, et al. Study of fluid flow in baffled vessels stirred by a Rushton standard impeller[J]. Applied Mathematics and Computation, 2016, (272):614-628.
[7]	SHARP K V, ADRIAN R J. PIV study of small-scale flow structure around a Rushton turbine[J]. AIChE Journal, 2001, 47(1):766-778.
[8]	ESCUDIE R, BOUYER D, LINE A. Characterization of trailing vortices generated by a Rushton turbine[J]. AIChE Journal, 2004, 50(1):75-86.
[9]	ESCUDIE R, LINE A. A simplified procedure to identify trailing vortices generated by a Rushton turbine[J]. AIChE Journal, 2007, 53(2):523-526.
[10]	宋戈. 涡轮桨搅拌槽内湍流特性的三维PIV实验研究[D]. 北京:北京化工大学, 2012. SONG G. The experiment investigation of fluid characteristics in the stirrer tank using stereo PIV[D]. Beijing:Beijing University of Chemical Technology, 2012.
[11]	SHARP K V, HILL D, TROOLIN D, et al. Volumetric three-component velocimetry measurements of the turbulent flow around a Rushton turbine[J]. Exp. Fluids, 2010, 48(1):167-183.
[12]	HILL D, TROOLIN D, WALTERS G, et al. Volumetric 3-component velocimetry (V3V) measurements of the turbulent flow in stirred tank reactors[C]//Proc. 14th Intern. Symp. Applications of Laser Techniques to Fluid Mechanics. Lisbon, Portugal, 2008:1-12.
[13]	鲍苏洋, 周勇军, 王璐璐, 等. 涡轮桨搅拌槽内流场特性的V3V实验[J]. 化工学报, 2016, 67(11):4580-4586. BAO S Y, ZHOU Y J, WANG L L, et al. V3V study on flow field characteristics in a stirred vessel with a Rushton turbine impeller[J]. CIESC Journal, 2016, 67(11):4580-4586.
[14]	张艳红, 杨超, 毛在砂. 大涡模拟搅拌槽中的液相流动[J]. 化工学报, 2007, 58(10):2474-2479. ZHANG Y H, YANG C, MAO Z S. Large eddy simulation of turbulent flow in a stirred tank[J]. Journal of Chemical Industry and Engineering(China), 2007, 58(10):2474-2479.
[15]	苗一, 潘家祯, 牛国瑞, 等. 多层桨搅拌槽内的宏观混合特性[J]. 华东理工大学学报(自然科学版), 2006, (3):357-360. MIAO Y, PAN J Z, NIU G R, et al. Mixing in stirred tanks with multiple impellers[J]. Journal of East China University of Science and Technology (Natural Science Edition), 2006, (3):357-360.
[16]	李志鹏, 高正明. 涡轮桨搅拌槽内单循环流动特性的大涡模拟[J]. 过程工程学报, 2007, 7(5):900-904. LI Z P, GAO Z M. Large eddy simulation of single loop flow field in a Rushton impeller stirred tank[J]. The Chinese Journal of Process Engineering, 2007, 7(5):900-904.
[17]	BAO Y, LI Z, GAO Z. PIV experiments and large eddy simulations of single loop flow fields in Rushton turbine stirred tank[J]. Chemical Engineering Science, 2011, 66(6):1219-1231.
[18]	LI Z P, BAO S Y. Stereo-PIV experiments and large eddy simulations of flow fields in stirred tanks with Rushton and curved-blade turbines[J]. AIChE Journal, 2013, 59(10):3986-4003.
[19]	BAKKER A, OSHINOWO L M. Modelling of turbulence in stirred vessels using large eddy simulation[J]. Trans. IChemE:Chem.Eng.Res., 2004, 82:1169-1178.
[20]	张兆顺, 崔桂香, 许春晓.湍流大涡数值模拟的理论和应用[M]. 北京:清华大学出版社, 2009:236-247. ZHANG Z S, CUI G X, XU C X. Theory and Application of Turbulent Large Eddy Simulation[M]. Beijing:Tsinghua University Press, 2009:236-247.
[21]	MENEVEAU C, KATZ J. Scale-invariance and turbulence models for large-eddy simulation[J]. Annual. Rev. Fluid Mech., 2000, 32:1-32.
[22]	DERKSEN J, VAN D, AKKER E A. Large eddy simulations on the flow driven by Rushton turbine[J]. AIChE Journal, 1999, 45(2):209-221.
[23]	周勇军, 卢源, 陈明濠, 等. 改进型INTER-MIG搅拌槽内固液悬浮特性的数值模拟[J]. 过程工程学报, 2014, (5):744-750. ZHOU Y J, LU Y, CHEN M H, et al. Numerical simulation of solid-liquid suspension characteristics in a stirred tank with improved INTER-MIG impeller[J]. The Chinese Journal of Process Engineering, 2014, (5):744-750.
[24]	ZHOU G, KRESTA S M. Impact of tank geometry on the maximum turbulence energy dissipation rate for impellers[J]. AIChE Journal, 1996, 42(9):2476-2490.
[25]	YOON H S, HILL D F, BALACHANDAR S, et al. Reynolds number scaling of flow in a Rushton turbine stirred tank(Ⅰ):Mean flow, circular jet and tip vortex scaling[J]. Chemical Engineering Science, 2005, 60(12):3169-3183.
[26]	YOON H S, BALACHANDAR S, MAN Y H. Large eddy simulation of flow in an unbaffled stirred tank for different Reynolds numbers[J]. Physics of Fluids, 2009, 21(8):137-1.