导　　师： 金同轨

学科专业： 081403

授予学位： 博士

作　　者： ;

机构地区： 西安建筑科技大学

摘　　要： 以黄河高浊度水为代表的高浓度悬浊液的沉降基本属于干扰沉降现象。 传统的干扰沉降理论与公式未能说明静水与动水絮凝过程各个参数对絮体形态及其结构的影响,不能定量与真实地反映干扰沉降时的实际情况。论文运用分形数学理论把絮体的静止结构与其生长、破碎等动态过程结合起来,对黄河高浊度水的沉降规律、投加高分子絮凝剂后的絮体分形特性、生长模式及絮体构造动态演变过程作深入的研究。从而更准确地定量描述与解释絮凝过程,预测絮凝结果,有效控制整个絮凝过程的各个变量,达到最佳絮凝效果。 本文主要研究黄河泥沙与阳离子高分子聚合物絮凝形成的絮凝体的分形特性以及水力流动特性对絮凝体分形特性的影响;探讨剪切絮凝条件下高分子絮凝剂的架桥絮凝机理与絮凝体分形结构的动态演变过程;通过相同絮凝条件下高岭土颗粒及标准粒子与高分子絮凝剂的架桥絮凝实验,进一步分析探讨了黄河高浊度水架桥絮凝体的分形特性与高分子絮凝剂的吸附性能与分形行为。 泥沙絮凝体结构具有广泛意义上的自相似性。在快速与陧速搅拌阶段,絮凝体的生长机制分别以DLCA模式和RLCA模式为主。利用密度-密度相关函数基于计盒维数中的网格法理论计算不同絮凝条件下絮凝体的分维D2=1.4±0.1～1.9±0.1;利用沉降实验数据由絮凝体干质量与当量球体粒径的函数关系求出不同絮凝条件下形成的絮凝体的分维D3=1.7±0.1～2.2±0.1。 本文采用沉降技术及图像分析技术分析探讨了泥沙架桥絮凝体的分形特性,并得到表征絮凝体分形特性的各个参数/(如絮凝体粒径、孔隙率、有效密度、沉速、强度等/)与分数维D/_3存在某种相关关系。 /(1/) 粒径分布: 絮凝体粒径分布曲线形状类似广义的正态分布。粒径分布扩展范围可用参数“分维D”表述。D>2时,峰值的粒径扩展范围相对要窄。当分维D降低时,粒径分布范围扩宽。从沉降数据得到粒径分布与分维的函数关系为: The settling of high-turbidity raw waters of Yellow-River mudsands on behalf of high concentration suspension liquids mainly belongs to phenomenon of "interference settling" or "zone settling".Conventional interference settling theories and formulae can't illustrate the effects of each of parameters on floe morphologies and structures during static and dynamic floeeulation processes and can't reflect real conditions of interference settling processes quantitatively and truly. Fractal mathematical theories are applied to combine static floe structures with its dynamic processes of growth and breakage etc. Furthermore, Fractal mathematical theories are used to study the settling regularities of high-turbidity raw waters of Yellow-River mudsands and floe fractal properties and growth models and the dynamic evolution processes of fractal structure by addition high molecular weight polymeric flocculants. So, we can describe and explain floeeulation processes exactly and quantitatively and predict floeeulation results, as well as we can control each of parameters effectively during floeeulation processes, so as to achieve optimum floeeulation efficiencies.In this dissertation, we mainly study aggregates fractal properties formed from bridging-flocculated processes of Yellow-River mudsands and canonic high molecular weight polymeric flocculants and the effects of hydrodynamic flow behavior on fractal properties; Under Shear-induced floeeulation conditions, bridging-flocculated mechanism of high molecular weight polymeric flocculants and dynamic evolution processes of fractal structure are discussed; Under the same floeeulation conditions, by bridging-flocculated settling experiment for kaolin particles and standard particulates by addition high molecular weight polymeric flocculants, fractal properties of bridging-flocculated aggregates of Yellow-River mudsands and adsorption properties and fractal behavior of high molecular weight polymeric flocculants are analyzed and discussed further. Mudsands aggregates structure formed from different flocculation conditions have self-similar structure widely. During the rapid and slow shear flocculation stages; growth mechanism of aggregates is Diffusion-Limited Cluster Aggregation /(DLCA/) model and Reaction-Limited Cluster Aggregation /(RLCA/) model mainly. Under different flocculation conditions, density-density correlation function on the basis of lattice method of box-counting dimension can be applied to calculate aggregates fractal dimension D2=1.4±0.1~1.9±0.1 and dry solid mass of aggregates as a function of equivalent sphere diameter in the three dimension space can be used to calculate fractal dimension D3=1.7+0.1 ~2.2 ± 0.1 by using settling experiment datum.Fractal properties bridging flocculation of mud sands aggregates are analyzed and discussed by application of settling and image analysis technologies and obtain the relation of fractal properties of aggregates which characterized by following parameters: floc size, floc voids, effective mass density, sedimentation rate, strength etc with fractal dimension D3./(1/) floc size distributionThe shape of aggregates size distribution curve is similar to generalized normal distribution. The width of size distribution range can be indicated by parameter" fractal dimension D". When D>2, there is a fairly narrow spread sizes about the peak value. As fractal dimension is lowered, there is a shift towards a broader size distribution. The responding size distribution as a function of fractal dimension in terms of settling experimental datum can be expressed as following:During the whole flocculation processes, three size regions are immediately apparent in the data: ①10 - 150um, mainly with the "primary particles" and RLCA aggregates; ②150 - 300um, primarily with the DLCA aggregates and RLCA aggregates; and ③>300um, chiefly with the DLCA aggregates./(2/) floe sedimentation rateswhen fractal dimension D is around critical value 2, there is a quite dramatic differences between aggregates sedimentation rates: when ZX2, the lower the fractal

关 键 词： 黄河泥沙 沉降 图像分析 质量分维 阳离子高分子聚合物 絮凝机理 吸附性能 水力流动特性 絮凝体最佳结构 分形特性

分 类 号： [TV142]

领　　域： [水利工程]