流场剪切力对微生物污垢影响的CFD模拟

CFD simulation of flow field shear stress effects on biofouling

再生水水质复杂,在再生水源热泵板式换热器中极易形成微生物污垢,严重影响换热性能和系统安全。在微生物污垢的研究中,微生物污垢所处流场与微生物污垢的受力和生长是密不可分的。利用CFD方法,借助FLUENT软件,对微生物污垢所处流场进行模拟,从改变流场和强化剪切力的角度出发,主要探究了在矩形流道的基础上,加入主动脉冲流、含有微刻痕、含有颗粒相的流场剪切力对微生物污垢生长的影响。模拟结果显示:方波形式的脉冲流以及微刻痕可以有效增加壁面剪切力,且脉冲周期越小、微刻痕尺寸越小,壁面剪切力增加越多;含有颗粒相的流场,随着颗粒粒径的增加,颗粒个体碰撞概率增加,单位质量碰撞概率减小。

Due to the complexity of treat sewage quality, composite fouling composed mainly of biofouling can easily form on surfaces of plate heat exchangers, and the biofouling can seriously affect the heat transfer efficiency and system security. In the research of biofouling, the force and growth of the biofouling is closely related to the flow field. In this paper, the CFD methods and FLUENT software are used to simulate the flow field of biofouling. From the view point of changing the flow field and intensifying the wall shear stress, this paper mainly researches on the influences of adding initiative pulse stream, using textured surfaces and adding particulate phase in the rectangular channel on the biofouling growth. The results show that pulse flow in the form of square wave and micro-patterned surface flow field can increase the wall shear stress efficiently. The wall shear stress increases with the decrease of pulse flow period or the micro-pattern size. As for the flow field containing particulate phase, when the particle diameter becomes larger, the individual collision probability increases and the mass collision probability decreases.