发酵罐内流场的数值模拟及桨叶优化

针对目前斜叶桨餐厨垃圾厌氧发酵罐存在搅拌能耗高、流场混合效果差等问题设计了新型轴流式搅拌桨( axial-flow impeller，AFI)。采用FLUENT软件对斜叶桨和AFI桨发酵罐内流场进行数值模拟，通过斜叶桨发酵罐单相水体系时搅拌功率计算值与模拟值的比较验证数值模拟的可靠性，并对比2种发酵罐中单相流场分布、固相体积分数分布和功率消耗情况。结果表明：单相水体系时，AFI桨改善了发酵罐内流场结构，搅拌功率较斜叶桨下降40. 39%；固液体系时，AFI桨发酵罐内固相体积分数分布更为均匀，罐底沉积现象不明显，搅拌功率较斜叶桨下降17. 37%。研究结果为餐厨垃圾厌氧发酵罐搅拌桨的设计与选择提供参考。

Numerical Simulation of Flow Field and Design of New Blade in Fermentation Tank

Traditional food waste anaerobic fermentation tank has high energy consumption and poor flow field mixing , inorder to solve this problem nowadays a new type of axial mixing impeller( AFI) was designed, Fluent software was usedto simulate flow field in the tank with oblique blade and AFI blade. The reliability of the numerical simulation wasverified through the comparison of calculated values and simulation values of mixing power with oblique blade in singlephase water system. The distribution of single phase flow field distribution. solid concentration distribution and powerconsumption of the two tanks were compared. The results showed that in the single-phase water system. AFI bladeimproved the structure of the flow field and decreased 40. 39% mixing power compared with the oblique blade. In theSolid-fluid system, AFI blade dispersed solid phase particles more evenly. Tank bottom sediment phenomenon was notobvious and new AFI blade decreased 17. 37% mixing power compared with the oblique blade. The research resultsprovided the reference to the design and selection of blade in the food waste anaerobic fermentation tank.