Calculation of Metzner Constant for Double Helical Ribbon Impeller by Computational Fluid Dynamic Method

• Published in: Chinese journal of chemical engineering Vol. 16; no. 5; pp. 686 - 692
• Main Author: 张敏革 张吕鸿 姜斌 尹玉国 李鑫钢
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2008
• Subjects: computational fluid dynamic; double helical ribbon impeller; Metzner constant; non-Newtonian fluid; 化学工程; 化工过程; 双螺带桨Metzner常数; 模拟计算; 计算流体力学; computational fluid dynamic; non-Newtonian fluid; double helical ribbon impeller; Metzner constant
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/S1004-9541(08)60141-X

Using the multiple reference frames （MRF） impeller method, the three-dimensional non-Newtonian flow field generated by a double helical ribbon （DHR） impeller has been simulated. The velocity field calculated by the numerical simulation was similar to the previous studies and the power constant agreed well with the experimental data. Three computational fluid dynamic （CFD） methods, labeled Ⅰ, Ⅱ and Ⅲ, were used to compute the Metzuer constant k5. The results showed that the calculated value from the slop method （method Ⅰ） was consistent with the experimental data. Method Ⅱ, which took the maximal circumference-average shear rate around the impeller as the effective shear rate to compute ks, also showed good agreement with the experiment. However, both methods suffer from the complexity of calculation procedures. A new method （method Ⅲ） was devised in this paper to use the area-weighted average viscosity around the impeller as the effective viscosity for calculating k5. Method Ⅲ showed both good accuracy and ease of use.