多层刚柔组合桨诱发流场界面失稳强化非牛顿流体混沌混合行为  

Chaotic mixing behavior of non-Newtonian fluid intensified by multilayer rigid-flexible impeller induced flow field interface instability

作　　者：刘作华[1,3] 杨林荣 熊黠[1,3] 陶长元 王运东[2] 程芳琴[4] LIU Zuohua;YANG Linrong;XIONG Xia;TAO Changyuan;WANG Yundong;CHENG Fangqin(School of Chemistry and Chemical Engineering,Chongqing University,Chongqing 400044,China;Department of Chemical Engineering,Tsinghua University,Beijing 100084,China;State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;Institute of Resources and Environment Engineering,Shanxi University,Taiyuan 030006,Shanxi,China)

机构地区：[1]重庆大学化学化工学院,重庆400044 [2]清华大学化学工程系,北京100084 [3]煤矿灾害动力学与控制国家重点实验室,重庆大学,重庆400044 [4]山西大学资源与环境工程研究所,山西太原030006

出　　处：《化工学报》2020年第12期5470-5478,共9页CIESC Journal

基　　金：国家重点研发计划项目(2017YFB0603105);国家自然科学基金项目(21636004);重庆市教委科学技术研究计划项目(KJZDM201900101);重庆市技术创新与应用示范专项产业类重点研发项目(cstc2018jszx-cyzdX0085)。

摘　　要：传统多层刚性桨用于假塑性非牛顿流体混合搅拌死区较大,流场界面稳定,混合效率低。提出多层刚柔组合桨诱发流场界面失稳强化非牛顿流体混沌混合的方法。实验以羧甲基纤维素钠为非牛顿流体体系,通过扭矩传感器测量功率特性,酸碱中和脱色法测定混合时间,并利用Matlab软件编程计算最大Lyapunov指数,分析了非牛顿流体混合过程中的混沌特性及其混合性能。结果表明,组合方式为RF-(PBTD+PBTD+DT)、桨叶排列方式θ=60°、柔性片长度安装比例r=0.8、1.2时,混沌程度较高,混合性能较好。多层刚柔组合桨可以产生多股螺旋流,并在层间柔性片扰动频率差下实现流场界面失稳,搅拌死区减小,在较低转速下使体系进入混沌状态(多层刚柔组合桨体系N>88 r/min时LLE>0,多层刚性桨体系N>125 r/min时LLE>0);在相同转速下,多层刚柔组合桨混合速率、单位体积功率高于多层刚性桨,而单位体积混合能大致相同。The traditional multilayer rigid impeller has large dead zone for the mixing of pseudoplastic non-Newtonian fluid,stable flow field interface and low mixing efficiency.A method for enhancing the chaotic mixing of non-Newtonian fluid by multilayer rigid-flexible impeller induced flow field interface instability was proposed.In the experiment,sodium carboxymethylcellulose was used as the non-Newtonian fluid system.The power characteristics were measured by the torque sensor.The mixing time was determined by the acid-base neutralization and decolorization method.The largest Lyapunov exponents were calculated by using Matlab software programming.The chaotic characteristics and mixing performance in the mixing process are analyzed.The results show that when the combination mode was RF-(PBTD+PBTD+DT),the impeller arrangement modeθ=60°,and the flexible sheet length installation ratio r=0.8,1.2,the degree of chaos was higher and the mixing performance was better.Multilayer rigid-flexible impeller can generate multiple spiral flows,and realize the flow field interface instability under the disturbance frequency difference of the flexible sheet between the layers,the stirring dead zone was reduced,and the system enters a chaotic state at a lower speed(when the multilayer rigid-flexible impeller system N>88 r/min,LLE>0;when the multilayer rigid impeller system N>125 r/min,LLE>0).At the same speed,the mixing rate and power per unit volume of the multilayer rigid-flexible combined impeller are higher than that of the multilayer rigid impeller,but the mixing energy per unit volume is approximately the same.

关 键 词：混沌 多层刚柔组合桨 非牛顿流体 混合 混合速率 最大LYAPUNOV指数 

分 类 号：TQ027.2[化学工程]