• 关键词：形态学  分形  絮凝体密度  脱水收缩  逐一附着

• 基金项目：国家教委“留学回国人员科研基金”;日本“文部省科学研究费”资助

• 王晓昌
• 西安建筑科技大学环境与市政工程学院, 西安 710055

• 丹保宪仁
• 北海道大学, 日本扎幌, 060-0008

• 摘要：常规混凝操作条件下形成的随机型絮凝体具有分形的特征,其分形维数D_f和絮凝体密度函数ρe∝dp-K_p的指数K_p之间具有D_f=3-K_p的关系.通过建立分布成长絮凝体模型,讨论了在絮凝过程中逐次导入颗粒间的空隙率对絮凝体密度和构造的影响.模型参数的分析结果进一步证明了分布成长的絮凝体是一个典型的分形,其分形维数取决于颗粒间空隙比ε和颗粒结合个数m.降低ε或提高m均有利于提高D_f,使絮凝体由松散型向致密型过渡.脱水收缩和逐一附着是达到这一目的的两种操作模式.

• Abstract：Random flocs formed under conventional operation condition are of fractal nature. There is a simple relation of D_f=3-K_p between D_f, the fractal dimension and K_p, the parameter in the floc density function ρ e∝d_p^-Kp.Through a stepwise agglomeration model, the process of floc growth was discussed. It was shown that at each agglomeration step, additional void water was entrapped in the floc and thus affected floc density and structure. By analyzing the parameters of the agglomeration model, it is further proved that a floc formed in this manner is of fractal nature with its fractal dimension depending on the void ratio ε and agglomerated particle number m. A decrease in ε or increase in m results in an increase in D_f, which implies a transition of floc from loose structure to compact one. Mechanical syneresis and one by one attachment are two operation modes for compact floc formation.

• Key words：morphology  fractal  floc density  syneresis  one-by-one attachment

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