用CFD软件模拟了3种传统径向流搅拌桨—平直叶式、半圆管式和非对称抛物线式搅拌桨的功率消耗和泵送能力等搅拌性能，研究了不同桨叶结构和尺寸对搅拌桨功率准数和泵送能力的影响，设计扇环抛物面桨叶结构，比较了新型桨与传统桨的功率准数、泵送效率等搅拌性能和轴向投影面积率的差异. 结果表明，桨叶外缘顶点曲率增大可减小功率准数和提高泵送效率，轴向高度减小可使功率准数降低但对泵送效率提升不大. 基于空间自由曲面设计的带有新型非对称扇环抛物面桨叶的搅拌桨操作性能最佳，比非对称抛物线式搅拌桨功率准数下降30.8%，泵送效率提高22.6%. 新型搅拌桨轴向投影面积率比非对称抛物线式搅拌桨增加21.5%，能用于气液分散操作.
The CFD simulations were carried out to study the power consumption and pumping performance of three traditional radial flow impellers—flat blade disc turbine, semi-circular disc turbine and asymmetric parabolic disc turbine BT (Bakker Turbine). The influence of various blades structure and size on the power number and pumping capacity of impellers was investigated. A novel impeller with annular sector paraboloid blades was designed and proposed. The stirring performance such as power number, pumping efficiency and axial projection area ratio between the new designed impellers and traditional impellers were compared. The results showed that increasing the vertex curvature of the blade outer edge would reduce the power number and improve the pumping efficiency. Reducing the axial height of the blade outer edge would also reduce the power number, but the pumping efficiency was not improved. The impeller FT (Fan-shaped Turbine) with a novel asymmetric annular sector paraboloid blade based on spatial free-form surface design showed the best operational performance. Compared with BT impeller, the power number of the fan-shaped turbine was decreased by 30.8%, the pumping efficiency was increased by 22.6%, and the axial projection area ratio of impeller was increased by 21.5%. The novel impeller would have a promising application in gas-liquid dispersion operations.
[1]Van’t Riet K.Smith JM. The trailing vortex system produced by Rushton turbine agitators[J].Chemical Engineering Science, 1975, 30(9):1093-1105 [2]Van’t Reit K.Boom JH.,Smith J. M. Power consumption,impeller coalescence and recirculation in agitated vessels[J].Chemical Engineering Research and Design, 1976, 54(2):124-131 [3]Bakker, A. Impeller assembly with asymmetric concave blades [P]. US, 5791780, 1998-08-11. [4]Yang J, Bao Y Y, Lin M L, et al.Experimental study and numerical simulation of local void fraction in cold-gassed and hot-sparged stirred reactors [J].Chemical Engineering Science, 2013, 100:83-90 [5]Bao Y Y, Gao Z M, Li Z P, et al.Solid suspension in a boiling stirred tank with radial flow turbines[J].Industrial and Engineering Chemistry Research, 2008, 47(7):2420-2427 [6]Li W B, Geng X Y, Bao Y Y, et al.Micromixing characteristics in a gas-liquid-solid stirred tank with settling particles[J].Chinese Journal of Chemical Engineering, 2015, 23:461-470 [7]马志超, 包雨云, 高娜, 等.不同叶片形状盘式涡轮搅拌桨的气-液分散特性[J].过程工程学报, 2009, 9(5):854-859 [8]Wang H N, Jia X Q, Wang X, et al.CFD modeling of hydrodynamics characteristics of a gas-liquid two-phase stirred tank[J].Applied Mathematical Modeling, 2014, 38:63-92 [9]郭武辉, 潘家祯.计算流体力学用于搅拌器流场研究及结构设计[J].化学工程, 2009, 37(9):20-23 [10]刘凯, 舒安庆, 马长春, 等.生物反应器的模拟及结构设计[J].化工设备技术, 2012, 33(2):14-17 [11]葛春燕, 王嘉俊, 顾雪萍, 等.和在搅拌桨设计和优化中的应用[J].化工与医药工程, 2014, 35(1):29-33 [12]Bakker, A.Smith,JM.,Myers,K. J. How to disperse gases in liquids[J].Chemical Engineering, 1994, 101(12):98-102 [13]Yoann Guntzburger, André Fontaine, Louis Fradette.An experimental method to evaluate global pumping in a mixing system: application to the maxblendTM for Newtonian and non-newtonian fluids[J].Chemical Engineering Journal, 2013, 214:394-406 [14]李晶, 詹晓北, 郑志永, 等.不同型式搅拌桨对黄原胶水溶液搅拌效果的数值模拟[J].过程工程学报, 2009, 9(4):634-640 [15]Qiao S C, Wang R J, Yang X X, et al.CFD prediction of mean flow field and impeller capacity for pitched blade turbine[J].Transactions of Tianjin Univercity, 2015, 21:250-258 [16]韩丹, 李龙, 程云山, 等.现代搅拌技术的研究进展[J].食品与机械, 2004, 20(4):31-34 [17]Myers K J, Thomas A J, Bakker A, et al.Performance of a gas dispersion impeller with vertically asymmetric blades[J].Chemical Engineering Research and Design, 1999, 77(A8):728-730 [18]Smith J M, Gao Z.Power demand of gas dispersing impellers under high load conditions[J].Chemical Engineering Research and Design, 2001, 79(5):575-580 [19]Verma M K, Tyagi R K.Study of specific power input and mass transfer coefficient in aeration of volatile organic compounds[J].International Journal of Resources and Environmental Engineering, 2013, 5(3):141-145
