Large Eddy Simulations of Mixing Time in a Stirred Tank

Abstract

Abstract: Large eddy simulations (LES) of mixing process in a stirred tank of 0.476m diameter with a 3-narrow blade hydrofoil CBY impeller were reported. The turbulent flow field and mixing time were calculated using LES with Sma-gorinsky-Lilly subgrid scale model. The impeller rotation was modeled using the sliding mesh technique. Better agree-ment of power demand and mixing time was obtained between the experimental and the LES prediction than that by the traditional Reynolds-averaged Navier-Stokes (RANS) approach. The curve of tracer response predicted by LES was in good agreement with the experimental. The results show that LES is a reliable tool to investigate the unsteady and quasi-periodic behavior of the turbulent flow in stirred tanks.

Key words: large eddy simulations, subgrid scale model, mixing time, hydrofoil impeller

关键词: large eddy simulations;subgrid scale model;mixing time;hydrofoil impeller

MIN Jian and GAO Zhengming. Large Eddy Simulations of Mixing Time in a Stirred Tank[J]. .

闵健,高正明. Large Eddy Simulations of Mixing Time in a Stirred Tank[J]. CIESC Journal.

References

1    Mezaki, R., Mochizuki, M., Ogawa, K., Engineering Data on Mixing, Elsevier Science, Amsterdam, 85—115 (2000).
2    Ranade, V.V., Bourne, J. R., Joshi, J.B., “Fluid mechan-ics and blending in agitated tanks”, Chem. Eng. Sci., 46, 1883—1893 (1991).
3    Lunden, M., Stenberg, O., Andersson, B., “Evaluation of a method for measuring mixing time using numerical simulation and experimental data”, Chem. Eng. Com-mun., 139, 115—136 (1995).
4    Schmalzriedt, S., Reuss, M., “Application of computa-tional fluid dynamics to simulations of mixing and bio-technical conversion processes in stirred tank bioreac-tors”, In: Proc. 9th Eur. Conf. Mixing, Paris, 171—178 (1997).
5    Jaworski, Z., Bujalski, W., Otiomo, N., “CFD study of homogenization with dual Rushton turbines comparison with experimental results”, Trans. IChemE, 78A, 327—333 (2000).
6    Eggels, J.G.M., “Direct and large-eddy simulation of turbulent fluid flow using the Lattice-Boltzmann scheme”, Int. J. Heat Fluid Flow, 17(3), 307—323 (1996).
7    Revsted, J., Fuchs, L., Tragardh, C., “Large eddy simula-tion of the turbulent flow in a stirred reactor”, Chem. Eng. Sci., 53(24), 4041—4053 (1998).
8    Revsted, J., Fuchs, L., “Influence of impeller type on the flow structure in a stirred reactor”, AIChE J., 46(12), 2373—2382 (2000).
9    Derksen, J., Harry, E., Akker, V., “Large eddy simula-tions on the flow driven by a Rushton turbine”, AIChE J., 45(2), 209—221 (1999).
10    Derksen, J., “Assessment of large eddy simulations for agitated flows”, Trans. IChemE, 79A, 824—830 (2001).
11    Hou, S., Wang, Y., Zhang, Z., Shi, L., “Turbulence flow generated by axial impeller”, J. Chem. Ind. Eng. (China), 51(2), 259—263 (2000). (in Chinese)
12    Gao, Z., Niu, G., Shi, L., Smith, J. M., “Mixing in stirred tanks with multiple hydrofoil impellers”, In: Proc. 11th Eur. Conf. Mixing, Bamberg, 14—17 (2003).
13    Gao, Z., Shi, L., “Effect of temperature on gas hold-up in aerated stirred tanks”, Chinese J. Chem. Eng.,  11(2),  204—207 (2003).
14    Zhou, G., “Experimental and numerical study on fluid dynamics and mixing process in stirred tank”, Ph. D. Thesis, Beijing Univ. Chem. Tech., Beijing (2002). (in Chinese)
15    Sun, H., Wang, W., Mao, Z., “Numerical simulation of the whole three-dimensional flow in a stirred tank with anisotropic algebraic stress model”, Chinese J. Chem. Eng., 10(1), 15—24 (2002).
16    Yeoh, S., Papadakis, G., Lee, K., “Large eddy simulation of turbulent flow in rushton impellers stirred reactor with a sliding-deforming mesh methodology”, In: Proc. 11th Eur. Conf. Mixing, Bamberg, 39—46 (2003).
17    Naude, I., Xuereb, C., Bertrand, J., “Direct prediction of the flows induced by a propeller in an agitated vessel using an unstructured mesh”, Can. J. Chem. Eng., 76, 631—640 (1998).
18    Lu, Z.Y., Liao, Y., Qian, D.Y., “Large eddy simulations of a stirred tank using the Lattice Boltzmann method on a nonuniform grid”, J. Comput. Phys., 181, 675—704 (2002).
19    Bakker, A., Lanre, M., Elizabeth, M., “The use of large eddy simulation to study stirred vessel hydrodynamics”, In: Proc. 10th Eur. Conf. Mixing, Elsevier Science B.V., 247—254 (2000).
20    Costes, J., Couderc, J., “Study by laser Doppler anem-ometry of the turbulent flow: Influence of the size of the units—Ⅱ. Spectral analysis and scales of turbulence”, Chem. Eng. Sci., 43, 2765—2772 (1988).
21    Luo, J., Gosman, A., Issa, R., Middleton, J., Fitzgerald, M., “Full flow field computation of mixing in baffled stirred reactors”, Trans. IChemE., 71A, 342—344 (1993).
22    Oshinowo, L., Jaworski, Z., Dyster, K. N., “Predicting the tangential velocity field in stirred tanks using the multiple reference frames model with validation by LDA measurements”, In: Proc. 10th Eur. Conf. Mixing, Delft, 281—288 (2000).
23    Hartmann, H., Derksen, J., “Assessment of large eddy and RANS stirred tank simulations by means of LDA”, Chem. Eng. Sci., 59, 2419—2432 (2004).
24    Jaworski, Z., Wyszynski, M., Moore, I., Nienow, A., “Sliding mesh CFD—A predictive tool in stirred tank design”, Proc. IMechE., 211, Part E, 149—156 (1997).
25    Ruszkowski, S., “A rational method for measuring blending performance and comparison of different im-peller types”, In: Proc. 8th Eur. Conf. Mixing, 283—291 (1994).
26    Grenville, R., Ruszkowski, S., Garred, E., “Blending of miscible liquids in the turbulent and transional regimes”, In: 15th NAMF Mixing Conf., Banff, Canada, 1—5 (1995).

[1]	LIU Zuohua, XU Huiqin, GU Deyin, XU Chuanlin, XIE Zhaoming, TAO Changyuan, WANG Yundong. Chaotic mixing performance enhanced by single-wire flexible impeller in stirred vessel [J]. CIESC Journal, 2017, 68(12): 4592-4599.
[2]	TANG Qiao, YE Sishi, WANG Yundong. Mixing time and flow characteristic in square pump-mix mixer under different scale-up criteria [J]. CIESC Journal, 2016, 67(2): 448-457.
[3]	LIU Renlong, LI Shuang, LIU Zuohua, TAO Changyuan, WANG Yundong. Chaotic mixing enhanced by punched-flexible impeller in stirred vessel [J]. CIESC Journal, 2015, 66(12): 4736-4742.
[4]	LIU Zuohua, ZENG Qiqin, WANG Yundong, LIU Renlong, TAO Changyuan. Energy efficiency analysis for high-viscosity fluid mixing enhanced by flexible impeller [J]. CIESC Journal, 2013, 64(10): 3620-3625.
[5]	MENG Huibo1，WANG Yanfen2，YU Yanfang1，WANG Wei1，WANG Feng1，WU Jianhu1. Research progress of mixing time in jet mixing equipment [J]. Chemical Industry and Engineering Progree, 2012, 31(12): 2615-2625.
[6]	LEI Jianqi，ZHU He，CHEN Jianpei，WU Gaojie. Experimental study and CFD simulation for thrust coefficient of hydrofoil impellers [J]. , 2010, 29(3): 430-.
[7]	CAI Qingbai, DAI Gance. Flooding Characteristics of Hydrofoil Impeller in a Two-and Three-phase Stirred Tank [J]. , 2010, 18(3): 355-361.
[8]	ZHANG Qinghua，MAO Zaisha，YANG Chao，ZHAO Chengjun. Research progress of liquid-phase mixing time in stirred tanks [J]. , 2008, 27(10): 1544-.