超声波作用下污泥水分扩散过程的数值模拟  

Numerical Simulation on Mositure Diffusion Processo of Sludge Under the Effect of Ultrasound

作　　者：赵芳[1] 陈振乾[1] 施明恒[1] 

机构地区：[1]东南大学能源与环境学院,江苏南京210096

出　　处：《工程热物理学报》2011年第4期659-662,共4页Journal of Engineering Thermophysics

基　　金：高校博士点基金资助项目(No.20090092110005)

摘　　要：建立了超声波作用下污泥内部水分扩散模型,利用分形理论对超声波(20kHz)作用下污泥内部孔隙结构进行描述,探讨了超声波声能密度对污泥孔隙表面分形维数d_f及孔隙通道曲折度分形维数d_w的影响,在此基础上建立了超声波作用下多孔介质中液体有效扩散系数的分形模型,对不同声能密度超声波辐照下污泥水分扩散过程进行了数值模拟。研究发现,超声辐照使污泥内部的孔隙结构发生改变,污泥颗粒变得均匀细小,孔隙连通性增大,水分迁移通道的曲折度减小,同时污泥内部液体分子受到超声能激发,迁移速度加快,因此,超声辐照有效增大了污泥内部水分的扩散速率。A diffusion model for moisture transfer in sludge under the effect of ultrasound was established,the pore size distribution in sludge with ultrasonic irradiation（20 kHz） was described by fractal theory.The effects of ultrasonic energy density on pore surface fractal dimension d_f and tortuosity fractal dimension d_w were analyzed.Based on the fractal characterization,the fractal model of effective moisture diffusion coefficient in porous media was developed,and the moisture diffusion processes in sludge under ultrasonic irradiation with different acoustic energy densities were numerically simulated.The results showed that ultrasonic treatment can change the pore size distribution in sludge,the sludge floes are dispersed and the connectivity of pore is improved compared with original state of sludge without ultrasonic treatment.The liquid molecule subjected to excitation of ultrasonic energy migrates more quickly,and the tortuosity of pore channels decreases in favor of moisture transfer in sludge.Therefore,it can be concluded that ultrasonic irradiation is beneficial to enhance moisture diffusion process in sludge.

关 键 词：超声波 污泥 分形 孔隙 扩散 

分 类 号：TK124[动力工程及工程热物理—工程热物理]