改进型三斜叶-Rushton组合桨槽内流场特性研究

Flow field characteristics in a stirred tank with improvedthree-pitched blade-Rushton combined impellers

为将改进型三斜叶-Rushton组合桨高效应用于实际工程,通过计算流体动力学(CFD)对装配改进型三斜叶-Rushton组合桨搅拌槽内的流场进行了模拟研究,与三斜叶-Rushton组合桨进行了对比;并通过粒子图像测速(PIV)技术研究该组合桨槽内搅拌转速n、桨叶间距C2及离底距离C1的变化对流场产生的影响。结果表明当转速为100 r×min^(-1)时能有效改善槽底和上桨叶区域的混合效果,槽内速度分布相对均匀,实验结果和模拟结果吻合效果较好;模拟结果表明改进型三斜叶桨的泵吸效果较三斜叶桨更强,能有效缩小搅拌槽底部和内壁附近的低速区域,槽内混合效果更好;实验结果表明当桨叶间距为0.25h时,槽内速度分布更合理;当离底距离为0.3h时,上桨叶区的较低速区域进一步缩小。

In order to efficiently apply an improved three-pitched blade-Rushton combined impeller in practical engineering,the flow field in a stirred tank equipped with the improved three-pitched blade-Rushton combined impeller was simulated by computational fluid dynamics(CFD),and the flow field of the improved three-pitched blade-Rushton combined impeller was compared with that of the three-pitched blade-Rushton combined impeller.In addition,the particle image velocimetry(PIV)technology was used to study the effects of rotational speed n,impeller pitch C2 and installation height of impellers C1 on the flow field of the improved three-pitched blade-Rushton combined impeller in stirred tanks.The result shows that when the rotational speed N=100 r×min^(-1),the mixing effect of the bottom and upper blade areas in the stirred tank can be effectively improved,and the velocity distribution of the flow field in the stirred tank is relatively uniform.The experimental results are in good agreement with the simulation results.Numerical simulation results demonstrate that the improved three-pitched blade-Rushton combined impeller has stronger pumping effects than the three-pitched blade-Rushton combined impeller,and it can effectively reduce the area of low-velocity near the bottom and inner wall in the stirred tank,which results in better mixing effects.The experimental results show that the velocity distribution is more reasonable when C2=0.25h,and the lower velocity area of the upper blade area is further reduced when the installation height of impellers C1=0.3h.