紊流脉动对生物反应器运行影响的数值模拟

为研究紊流脉动对生物反应器运行的影响，针对时均速度为零的振动格栅反应器，构建气-液两相流模型并对其进行验证。借助Fluent软件对反应器中气和水的流动进行数值模拟，得出10种工况下紊流脉动强度与气含率、氧转移系数和雷诺应力的关系。结合实验测得的生物膜理化数据，分析紊流脉动强度对生物膜生长的影响。结果表明，增大紊流脉动可有效提高反应器内的气含率和氧转移系数，促进气液两相进行高效传质。对于本研究所用振动格栅生物反应器，当紊流强度q<2.7 cm/s时，生物膜厚度和密度随着紊流强度的增加而增加。当q>2.7 cm/s时，雷诺应力的作用显著，生物膜逐渐变薄变密。紊流强度q=3.4~4.8 cm/s时，生物膜生长和污染物去除效果最佳。

Simulation of the effect of turbulent pulsation on bioreactor operation

In order to study the effect of turbulence pulsation on the operation of bioreactor, a gas-liquid two-phase flow model was constructed and verified for a vibrating grille reactor with zero time-averaged velocity. The numerical simulation of gas and water flow in the reactor was carried out with the help of Fluent software, and the relationship between turbulent fluctuation intensity and gas holdup, oxygen transfer coefficient and Reynolds stress under ten working conditions was obtained. Based on the physical and chemical data of biofilm, the effect of turbulent pulsation intensity on biofilm growth was analyzed. The results show that increasing turbulent pulsation can effectively increase the gas holdup and oxygen transfer coefficient in the reactor and promote the high efficiency mass transfer between gas and liquid phases. For the vibrating grille bioreactor used in this study, when the turbulence intensity q<2.7 cm/s, the biofilm thickness and density increase with the increase of turbulence intensity, when q>2.7 cm/s, the Reynolds stress plays a significant role, the biofilm becoming thinner and denser gradually. The biofilm growth and pollutant removal effect is the best when the turbulence intensity q=3.4~4.8 cm/s. This study can provide a reference for the design and operation optimization of the bioreactor.