Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

›› 2011, Vol. 19 ›› Issue (2): 232-242.

Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

赵静, 高正明, 包雨云

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China

收稿日期:2010-10-12 修回日期:2011-03-04 出版日期:2011-04-28 发布日期:2011-04-28
通讯作者: BAO Yuyun,E-mail:baoyy@mail.buct.edu.cn
基金资助:
Supported by the National Natural Science Foundation of China(20776008,20821004,20990224);the National Basic Research Program of China(2007CB714300)

Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

ZHAO Jing, GAO Zhengming, BAO Yuyun

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China

Received:2010-10-12 Revised:2011-03-04 Online:2011-04-28 Published:2011-04-28
Supported by:
Supported by the National Natural Science Foundation of China(20776008,20821004,20990224);the National Basic Research Program of China(2007CB714300)

摘要/Abstract

摘要： Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their relationship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines,including Rushton turbine,concaved blade disk turbine,half elliptical blade disk turbine,and parabolic blade disk turbine.Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail.The location,size and strength of vortices were determined by the simplified λ₂-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics.The larger curvature resulted in longer residence time of the vortex at the impeller tip,bigger distance between the upper and lower vortices and longer vortex life,also leads to smaller and stronger vortices.In addition,the turbulent kinetic energy and turbulent energy dissipation in the discharge flow were determined and discussed.High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them.Although restricted to single phase flow,the presented results are essential for reliable design and scale-up of stirred tank with disc turbines.

关键词: trailing vortices, disc turbine, particle image velocimetry, blade shape

Abstract: Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their relationship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines,including Rushton turbine,concaved blade disk turbine,half elliptical blade disk turbine,and parabolic blade disk turbine.Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail.The location,size and strength of vortices were determined by the simplified λ₂-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics.The larger curvature resulted in longer residence time of the vortex at the impeller tip,bigger distance between the upper and lower vortices and longer vortex life,also leads to smaller and stronger vortices.In addition,the turbulent kinetic energy and turbulent energy dissipation in the discharge flow were determined and discussed.High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them.Although restricted to single phase flow,the presented results are essential for reliable design and scale-up of stirred tank with disc turbines.

Key words: trailing vortices, disc turbine, particle image velocimetry, blade shape

赵静, 高正明, 包雨云. Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines[J]. , 2011, 19(2): 232-242.

ZHAO Jing, GAO Zhengming, BAO Yuyun. Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines[J]. , 2011, 19(2): 232-242.

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Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

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