离心泵内细长颗粒的运动及其取向分布的研究

项目名称： 离心泵内细长颗粒的运动及其取向分布的研究

项目编号： No.51309118

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 水利工程

项目作者： 张启华

作者单位： 江苏大学

项目金额： 25万元

中文摘要： 为揭示造纸、排污流程离心泵的流动减阻机理，拟开展离心泵内含细长颗粒悬浮液的内流研究，从数值计算和实验两方面研究旋转流场中细长颗粒的输运现象。首先，研究旋转流场-颗粒间双向耦合的沉浸边界法，利用该方法开展单颗粒及多颗粒的流场数值计算，同时通过高速摄影从颗粒运动轨迹和取向演变两方面对沉浸边界法进行验证。然后，系统地研究颗粒初始位置、初始取向、长径比、体积浓度、泵进口流速及转速等对颗粒运动的影响。其次，为研究离心泵内含细长颗粒悬浮液的流变特征，提出旋转流场中的颗粒取向分布概率函数，同时运用高速摄影测得细长颗粒的取向分布。采用统计平均计算出二阶、四阶取向张量，由获得的取向张量修正取向分布概率函数。再利用修正的概率函数，结合应力-应变本构方程计算出附加损失。最后，通过研究颗粒取向分布造成的附加损失及其在旋转流场中的分布特征，阐明离心泵内细长颗粒悬浮流的减阻机理，为相关泵系统的节能提供解决方案。

中文关键词： 离心泵；纤维；取向；概率分布；水力设计

英文摘要： To uncover drag-reduction mechanism for pumps widely used in paper-making and sewage-treatment industries, a research project is proposed to investigate internal suspension flows of a centrifugal pump carrying slender particles. The transport phenomena of slender particles immersed in rotational flows are explored numerically and experimentally. Firstly, an immersed boundary method(IBM) is developed to resolve the rotational flow-particle two-way coupling. Based on IBM, the transport process of suspensions containing one or more particles are simulated respectively. Meanwhile, a high-speed photograph is used to capture the trajectories of slender particles and to obtain their orientation evolutions, which are further used to validate the IBM algorithm. Then the influence of such factors as particle initial position, particle initial orientation, particle aspect ratio, particle volume fraction, pump inlet velocity, and pump rotating speed on particle motion are investigated systematically. Secondly, a particle orientation distribution probability function is proposed, which is used to investigate the rheological property of rotational suspension flows containing slender particles. In the meantime, the high-speed photograph is used to capture the orientation distribution of slender particles. Through ensemble aver

英文关键词： centrifugal pump；fiber；orientation；probability distribution；hydraulic design