最大叶片式桨在假塑性流体中的搅拌流场模拟

为研究最大叶片式桨在高黏假塑性流体中的搅拌流动行为,以黄原胶溶液为研究体系,采用计算流体力学方法重点研究了釜内流体的功耗特性、速率分布、剪切速率、表观黏度分布和总体流动状况。结果表明:最大叶片式桨具有与大多数径流桨相似的双循环流型结构,且预测的功耗特性与实验数据一致性良好。最大叶片式桨适用于高黏假塑性流体的混合,而对于高黏牛顿流体的混合则效果不佳。釜内的剪切速率分布较宽泛,且受转速影响较大。转速可作为该桨改善黄原胶体系混合效率的重要参数之一。

Simulation of flow field of pseudoplastic fluids agitated by Maxblend impeller

To study the flow behavior of highly viscous pseudoplastic fluids agitated by Maxblend impeller,taking xanthan gum solution as research system,the power characteristics,the distribution of radial velocity,shear rates,apparent viscosity and the overall flow status in the vessel were emphatically studied by means of computational fluid dynamics.The result shows that Maxblend impeller presents a flow pattern structure of double circulation like most of radial flow impellers,and the predicted power characteristics shows a good coincidence with the experimental data.Maxblend impeller is suitable for the mixing of highly viscous non-Newtonian fluid,while has a poor mixing efficiency with that of Newtonian fluid.A wider distribution of shear rates was obtained in the stirred tank,which was strongly influenced by the rotational speed.The rotational speed can be used as one of the most important parameters to improve the mixing efficiency of xanthan gum solution.