›› 2007, Vol. 7 ›› Issue (3): 439-444.

• 流动与传递 •

### 高固含搅拌槽内临界离底悬浮转速的数值模拟

1. 北京化工大学化学工程学院
• 出版日期:2007-06-20 发布日期:2007-06-20

### Numerical Simulation of Critical Suspension Impeller Speed in a High Concentration Stirred Tank

ZHANG Feng-tao,LIU Fang,HUANG Xiong-bin

1. College of Chemical Engineering, Beijing University of Chemical Technology
• Online:2007-06-20 Published:2007-06-20

Abstract: Based on the function provided by CFX5.5.1, the critical suspension impeller speed, Njs, was simulated. The investigation was carried out in a fully baffled, flat bottom, cylindrical vessel, with 476 mm diameter, equipped with CBY (long thin blade) impeller. The clearance between the impeller and the bottom of the tank was D/3. The glass beads of 15~150 mm were chosen as the dispersed phase. The particle volume fraction was from 15% to 50%. Two different criteria were used to determine Njs from the numerical results. The original criterion is to identify the critical suspension by a sudden velocity increase with the impeller speed at the bottom center. The modified criterion is by observation of the velocity increase at the point with the most difficulty in suspension, i.e., at the radial position about 50 mm off the bottom center. The CFD predictions by the modified criterion are in good agreement with experimental data. At the bottom of the tank, turbulence kinetic energy at the critical impeller speed was also discussed.