管内脉动层流动力学特性研究  

Study of dynamics characteristics of laminar pulsed flow in pipe

作　　者：蔡玲玲[1] 米沙[1] 刘志强[1] CAI Lingling;MI Sha;LIU Zhiqiang(School of Energy Science and Engineering,Central South University,Changsha 410083,China)

机构地区：[1]中南大学能源科学与工程学院,湖南长沙410083

出　　处：《大连理工大学学报》2018年第5期464-470,共7页Journal of Dalian University of Technology

基　　金：国家自然科学基金资助项目(51676209);中央高校基本科研业务费专项资金资助项目(2017zzts170)

摘　　要：采用数值模拟方法对圆管内低频率脉动层流动力学特性进行了研究,分析了管内脉动层流速度以及流体剪切应力分布特性.研究结果表明:脉动层流中出现回流现象,且速度边界效应的范围与脉动频率有关.脉动频率越大,速度边界层范围越小,边界层内速度梯度越大.在边界层内,流体剪切应力的作用方向出现周期性变化.随着振幅A的增大,壁面剪切应力先增后降,然后再增,最后趋近于某一值.而管道压降随着振幅的增大最初变化并不明显,在A=0.6时压降急剧增大,而当A>0.8时明显降低.综合考虑脉动频率和振幅对壁面剪切应力与压降的影响规律,存在最佳振幅,且最佳频率为0~2.5Hz.The dynamics characteristics of laminar pulsed flow in a circular pipe with low frequency are studied by numerical simulation.The distribution characteristics of velocity and fluid shear stress of laminar pulsed flow in pipe are analyzed.The results indicate that the flow reversal happens in laminar pulsed flow and the range of velocity boundary effect is related to the pulsed frequency.The bigger the pulsed frequency is,the smaller the range of velocity boundary layer is,the greater the velocity gradient in boundary layer is.In the boundary layer,the direction of fluid shear stress changes periodically.The wall shear stress first increases and decreases with the increase of the amplitude A,then increases again,and finally reaches a certain value.The pressure drop of the pipe has no obvious change at first with the increase of the amplitude,it increases dramatically when A=0.6 and decreases obviously when A>0.8.Considering the influence of pulsed frequency and amplitude on wall shear stress and pressure drop,the amplitude has an optimum value and the pulsed frequency is best in range of 0-2.5 Hz.

关 键 词：脉动流 层流 剪切应力 压降 频率 

分 类 号：TB126[理学—工程力学]