改进型框式组合桨搅拌釜内流场特性

对5m³树脂反应釜及釜内改进型框式-二斜叶双层组合桨等比例缩小建立模型，基于计算流体力学（CFD）中的多重参考系法对该双层组合桨搅拌釜流场进行了模拟研究，并利用粒子图像测速（PIV）实验对模拟结果进行了验证。分析了桨叶离底间距、桨间距及组合桨安装角度的变化对流场产生的影响。随着离底间距的增大，搅拌釜下层框式桨横梁处产生往槽底的轴向流强度会逐渐减弱，不利于底部物料的混合；桨间距的增加导致两桨间对流减弱，不利于两桨间流体的混合，当桨间距与釜内径的比值为0.77时，搅拌釜内的整体流动情况较好。对上下层桨叶安装角度分别为0°、45°和90°这3种工况下的釜内流场特性研究表明，安装角度为90°时，斜叶桨产生的轴向流强度最大，此时搅拌釜内流体的混合效果最好。研究结果为改进型框式桨与二斜叶桨双层组合桨应用于树脂聚合反应实际工程提供参考。

Investigating on flow field in stirred tank equipped with improved frame type combined impellers

The 5m³ resin reactor equipped with an improved frame type-two oblique double layer combined impellers was scaled down，and its calculation model was established. The flow field in the mentioned stirred tank was numerically investigated by using multi-reference frame method based on the computational fluid dynamics (CFD) simulation code Fluent, and the simulation results were validated by PIV experiments. The effects on the flow field arising from the installation height of impellers (C₁), the distance between two impellers (C₂) as well as the installation angle of combined impeller (β) were investigated. With the increase of C₁, the axial flow from the beam of frame impeller to the bottom of the stirred tank will gradually decrease, which is not conducive to the mixing of the materials in the bottom of the tank. The increase of C₂ leads to the weakening of convection between the two propellers, which is not conducive to the mixing of fluid between the two propellers. When the ratio of propeller spacing to vessel diameter is 0.77, the overall flow in the stirred tank is better. The flow field characteristics of the blade installation angles of 0°, 45°and 90°show that the axial flow intensity produced by the inclined blade is the largest when β is 90°, and the mixing effect of the fluid in the stirred tank is the best. The results provide a reference for the application of the improved frame type-two oblique double layer combined impeller in the practical engineering of resin polymerization reaction.