穿流-四斜叶组合桨桨间距对搅拌槽内流场特性的影响

Effect of Impeller Pitch on the Flow Characteristics of Punched and Four-bladed Combination Impellers in a Stirred Tank

基于计算流体力学中的大涡模拟方法,对不同桨间距C_(2)下的穿流-四斜叶组合桨搅拌槽内的流动特性进行了模拟分析,并采用粒子成像测速技术进行了实验对比研究。研究结果表明,桨间距对两桨叶之间的连接流作用及整体混合效果的影响较大。C_(2)=0.24H(H为搅拌槽高度)时两桨叶之间的连接流较为稳定,但搅拌槽上层区域流动较差;当C_(2)增大到0.29H时,搅拌槽内两搅拌桨间的连接流呈现S型,整体的混合能力更强;当C_(2)增大到0.34H时,两桨叶间的连接流能力减弱,且搅拌槽内的流型依据搅拌桨位置分化为上下2个较大的局部混合区域。

Based on the large eddy simulation method in computational fluid dynamics,the flow characteristics in a stirred tank with the punched and four-bladed combination impellers at different impeller pitches C_(2)were simulated and analyzed,and the simulation results were compared with particle image velocimetry experiments.The research results show that the impeller pitch has a significant effect on the connecting flow between two blades and the overall mixing effect.When C_(2)=0.24H(H is the height of the stirred tank),the connecting flow between the two blades is relatively stable,but the flow in the upper part of the stirred tank is poor.When the impeller pitch increases to C_(2)=0.29H,the connecting flow between the two impellers in the stirred tank forms a S-shape and the mixing ability of the liquid is stronger.As the impeller pitch increases to C_(2)=0.34H,the connecting flow between the two impellers is weak and the flow pattern inside the stirred tank is divided into two large local mixing regions based on the position of the impellers.