摘要
利用滑移网格方法,采用三种不同密度的网格,计算了六直叶涡轮搅拌桨的三维流动场。利用数值方法得到了桨叶附近流动场中所产生的尾涡,并将不同密度网格下的数值模拟结果与实验数据进行了比较。计算结果表明,在高密度的网格下可以清楚地观察到桨叶附近所产生的尾涡,其大小与实验结果一致,但尾涡衰减较快;叶端的径向与切向速度分布与实验值吻合较好,加密网格对最大径向及切向速度的预测精度有明显提高;即使采用很高的网格密度,对湍流动能的预测仍然偏低。
The mixing processes depend on the magnitude and local distribution of turbulence that is generated by the stirrer. The trailing vortex system generated near the impeller blades, in particular, has been identified as the major flow mechanism responsible for mixing and dispersion in stirred vessels. Modeling the three-dimensional, transient motion of an impeller using the sliding mesh approach was the most rigorous and fully predictive analysis method of the field of stirred tank. The objective of this paper is to study the flow field near the impeller using this method. Numerical simulations of flow induced by a Rushton turbine were conducted using sliding mesh method with three kinds of density grid. The trailing vortices around the blade were resolved. Prediction results of different density grid were compared with experimental data. It was found that with high-density grid the trailing vortices achieved by the simulation were in good agreement with the experimental data, but damped quickly. The predicted radial and tangential velocity distributions around the blade tip were in good agreement with the experimental results. The grid density had great influence on the maximal radial and tangential velocity. Even with high-density grid, the turbulence kinetic energy was under-predicted severely.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2002年第1期17-22,共6页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金资助项目(29976002)
