江晓凤, 陈仕兴, 许恩乐, 孟献梁, 吴国光, 苗真勇. 基于高速动态摄像的气泡铺展过程动力学行为[J]. 煤炭学报, 2022, 47(7): 2825-2833.
引用本文: 江晓凤, 陈仕兴, 许恩乐, 孟献梁, 吴国光, 苗真勇. 基于高速动态摄像的气泡铺展过程动力学行为[J]. 煤炭学报, 2022, 47(7): 2825-2833.
JIANG Xiaofeng, CHEN Shixing, XU Enle, MENG Xianliang, WU Guoguang, MIAO Zhenyong. Dynamic behavior of bubble spreading based on highspeed camera[J]. Journal of China Coal Society, 2022, 47(7): 2825-2833.
Citation: JIANG Xiaofeng, CHEN Shixing, XU Enle, MENG Xianliang, WU Guoguang, MIAO Zhenyong. Dynamic behavior of bubble spreading based on highspeed camera[J]. Journal of China Coal Society, 2022, 47(7): 2825-2833.

基于高速动态摄像的气泡铺展过程动力学行为

Dynamic behavior of bubble spreading based on highspeed camera

  • 摘要: 泡沫浮选分离过程中,矿物颗粒的黏附行为包含液膜薄化、破裂和三相润湿周边的形成。 先前学者对液膜薄化及破裂机理展开了深入研究,而关于三相润湿周边的动力学演变行为尚未得 到充分关注。 采用高速动态摄像机追踪气泡在均质固体(特氟龙、有机玻璃、玻璃、不锈钢)以及非 均质固体(褐煤和无烟煤)表面的铺展过程,借助扫描电镜(SEM)、红外光谱仪和接触角测量仪分 析了固体表面物理化学结构特性,并运用 MATLAB 软件探究了均质与非均质固体表面三相线铺展 机理和气液界面形态演变规律。 气泡铺展实验结果表明,三相润湿周边主要经历快速铺展和慢速 铺展 2 个阶段,快速铺展阶段三相线时空演化呈现普遍的自相似行为特征,而慢速铺展阶段三相线 运动特性与固体界面性质密切相关。 采用幂律模型 L = atb 分析了气泡在均质固体表面铺展动力 学,结果表明快速和慢速铺展阶段分别呈现 1 / 2( 惯性控制区) 和 1 / 10( 黏性控制区) 指数,并且煤 样表面快速铺展阶段同样出现1/2指数特征。 基于固体表面物化结构分析得出,均质/非均质固体 表面疏水性越好,对气泡吸引力越大,其三相线铺展长度越长;固体表面越不规则,孔隙 / 沟壑越多, 对铺展过程三相线长度( L) 、气泡最大宽度( W) 及其对应位置( H) 影响越大;褐煤和无烟煤由于非 均匀物理化学结构而产生的钉扎效应以及气体融合效应,使得其三相线运动规律和气液界面形态 演变与均质固体相差较大。 总之,颗粒气泡黏附过程中三相线铺展行为与固体表面物理化学结构 及其均匀性密切相关。

     

    Abstract: During foam flotation,the adhesion process includes liquid film thinning,liquid film rupture and threephase wetting periphery formation.Previous scholars have conducted indepth research on liquid film thinning and rupture.However,the evolution of threephase wetting periphery has not yet been fully concerned.In this work,the highspeed dynamic camera was used to record the spreading process of bubbles on homogeneous solid(Teflon,plexiglass,glass,stainless steel) and heterogeneous solid(lignite and anthracite) surfaces.The scanning electron microscope(SEM),infrared spectrometer,and contact angle meter were adopted to analyze the physicochemical structures of solid surfaces.The MATLAB software was applied to investigate the spreading mechanism of threephase lines(TPL) and the morphological evolution of gasliquid interface on both homogeneous and heterogeneous solid surfaces.The experimental results of bubble spreading show that the threephase wetting periphery mainly undergoes two stages:rapid spreading and slow spreading.The TPL during the rapid spreading stage exhibits a general selfsimilar behavior with no independence on the initial conditions,while that during slow spreading stage is closely related to the solid surface properties.The powerlaw,L= at b,was utilized to analyze the spreading dynamics on homogeneous surfaces,and it demonstrated the 1/2(inertia regime) and 1/10(viscous regime) scaling exponents for rapid and slow spreading process,respectively.Also,the scaling exponent of 1/2 was obtained for the rapid spreading process of bubbles on coal surfaces.Based on the physicochemical structures of sloid surfaces,the better hydrophobic property of homogeneous or heterogeneous solid surfaces leads to the longer TPL length(L),due to the greater attraction force.The surfaces with more irregularities,grooves or pores,the greater the influence on TPL length(L),bubble maximum width(W) and corresponding position(H).Compared to the homogeneous surface,the heterogeneous physicochemical structure of lignite and anthracite leads to great difference on the motion dynamics of TPL and evolution of gasliquid interface,due to the pinning and fusion effect.Thus,the TPL spreading dynamics during particlebubble attachment are closely related to the surface physicochemical structures,as well as their homogeneity.

     

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