大型沼气厌氧池侧进式搅拌流场的数值模拟分析

为了研究直径和高度均为16 m的大型沼气池內单个侧进式搅拌器的搅拌效果,采用流体力学软件Fluent,以多重参考系法、RNGκ-ε湍流模型及压力-速度耦合SIMPLEC算法,对搅拌流场进行三维数值模拟,并分析了不同的安装角度、离底高度、搅拌转速及搅拌桨叶直径对搅拌功率、有效区百分比和防沉淀效果的影响。研究结果表明,当搅拌转速大于450 r/min和搅拌桨叶直径大于750 mm时,有效区百分比均达到最大值70%;当水平夹角α为30°时,搅拌效果达到最好;垂直夹角β偏向池底和离底高度小于8 m时,有利于防止池底沉淀的产生。

Numerical Simulation of Side Inlet Mixing Flow Field in Large Scale Biogas Tank

In order to study the stirring effects of a single side agitator in the large biogas digester with a diameter and height of 16 m,the fluid dynamics software Fluent was used to conduct the three-dimensional simulation of the stirred flow field with the multiple reference system,RNG κ-ε turbulence model and pressure velocity coupled SIMPLEC algorithm.The influence of different installation angles,bottom height,stirring speed and stirring diameter on the stirring power,the percentage of effective area and the anti-precipitation effects were analyzed.The results showed that when the stirring speed was greater than 450 r/min and the stirring diameter was more than 750 mm,the effective area percentage reached the maximum value of 70％.When the horizontal angle was 30 °,the stirring effect appeared to be the best.When the vertical angle was inclined to the bottom of the biogas digester and the height from the bottom was less than 8 m,it was conducive to prevent the precipitation on the bottom of the biogas digester.