高分子溶液壁湍流减阻机理的TRPIV实验研究  

TRPIV Experimental Investigation on Drag-Reduction Mechanism of Polymer Solution Wall Turbulence

作　　者：蒋营营[1,2] 管新蕾[1,2] 姜楠[1,2,3,4] 

机构地区：[1]天津大学力学系,天津300072 [2]天津市现代工程力学重点实验室,天津300072 [3]中国科学院力学研究所非线性力学国家重点实验室,北京100090 [4]南开大学天津大学刘徽应用数学中心,天津300072

出　　处：《实验力学》2013年第4期422-430,共9页Journal of Experimental Mechanics

基　　金：国家自然科学基金资助项目(11272233);国家重点基础研究发展计划(973)资助项目(NO.2012CB720101);中国科学院力学研究所非线性力学国家重点实验室对外开放课题联合资助

摘　　要：利用高时间分辨率粒子图像测速技术(TRPIV)对回流式水槽中低浓度高分子溶液壁湍流的减阻机理进行实验研究。通过对比分析高分子溶液和纯水平板湍流边界层在相同来流速度下的平均速度剖面、湍流强度和雷诺应力,发现高分子溶液的壁面摩擦阻力减小了21.77%,并且其缓冲层增厚,按对数律外移,雷诺应力减小;高分子聚合物主要在近壁区起到抑制湍流脉动的作用,而在主流区的作用不太明显。用流向局部平均多尺度速度结构函数和相干结构条件采样方法,检测并对比了高分子溶液和水的壁湍流相干结构"喷射"和"扫掠"事件中的脉动速度、展向涡量、雷诺应力等物理量的二维拓扑形态,发现高分子溶液近壁区相干结构在猝发时的脉动速度减小,涡量受到抑制,雷诺应力明显减小,说明高分子溶液湍流近壁区相干结构"喷射"和"扫掠"的强度变弱,猝发频率降低,动量和能量的输运减弱,揭示出高分子溶液减阻的重要机理。Experimental study of drag reduction mechanism of low concentration polymer solution wall turbulence in a regurgitant water channel was carried out by using time-resolution particle image velocimetry （TRPIV）. Through comparative analysis of the average velocity profile, the turbulence intensity and Reynolds stress for flat plate turbulent boundary layer flow of both polymer solution and pure water at the same incident flow velocity, it is found that the skin friction of polymer solution is decreased 21.77~, its buffer layer is thickened and relocated by logarithmic law, its Reynolds stress is decreased in polymer solution, respectively. PAM polymers restrain the turbulence fluctuation mostly in near-wall region, in the main stream region, its role is not significant. By using local average multi-scale flow velocity structure function along flow direction and coherent structures conditional sampling method, the two-dimensional topologies of the fluctuating velocity, the spanwise velocity, Reynolds stress and other physical quantities in wall turbulence burst coherent structure ＂jet＂ and ＂sweep＂ events for both polymer solution and water were detected and compared. Results show that the fluctuating velocity in near-wall region coherent structure decreases, the vorticity is suppressed, and Reynolds stress decreases obviously, which indicate that the turbulence intensity of ＂jet＂ and ＂sweep＂ in polymer solution near-wall region decreases, burst frequency reduces, momentum and energy transport weakens. Above results reveal the important drag reduction mechanism of polymer solution.

关 键 词：高分子溶液 减阻 高时间分辨率粒子图像测速 壁湍流 相干结构 

分 类 号：O357.52[理学—流体力学]