弧形涡流发生器对湍流相干结构及强化换热的影响  

Effect of arc-shaped vortex generator on coherent structures and heat transfer enhancement in turbulence

作　　者：管新蕾 孙小姣 王维 王利军[1] GUAN Xinlei;SUN Xiaojiao;WANG Wei;WANG Lijun(School of Low–Carbon Energy and Power Engineering,China University of Mining and Technology,Xuzhou 221116,China;School of Mechanical&Electrical Engineering,Xuzhou University of Technology,Xuzhou 221018,China)

机构地区：[1]中国矿业大学低碳能源与动力工程学院,徐州221116 [2]徐州工程学院机电工程学院,徐州221018

出　　处：《实验流体力学》2024年第4期104-112,共9页Journal of Experiments in Fluid Mechanics

基　　金：国家自然科学基金项目(11802331);中国矿业大学实验技术研究与开发项目(S2023Y007);中国矿业大学教学学术研究重大课题(2023ZDKT04)。

摘　　要：涡流发生器是一种常见的被动强化换热元件,因高性价比而受到广泛应用。本文针对带有弧形涡流发生器的方形管道,采用高时间分辨率粒子图像测速(Time-Resolved Particle Image Velocimetry,TRPIV)技术和大涡模拟(Large Eddy Simulation,LES)方法,研究了涡流发生器诱导的湍流相干结构特征及其对涡流发生器强化换热的影响。实验分析表明,湍流特征量统计图捕捉到了发卡涡涡腿和低速条带的印记。利用涡旋辨识准则提取了发卡涡和反向旋转的准流向涡对(Counter-rotating quasi-streamwise Vortices Pair,CVP),两者在弧形涡流发生器诱导的流场中共存且相互作用,随着涡旋结构演变与发展,其展向尺度不断增大。为研究湍流相干结构与强化换热的关系,通过数值模拟分析了湍流相干结构与温度梯度的空间分布情况,发现两者的分布具有良好的区域一致性,反映了湍流相干结构对强化换热的影响与控制。对比安装弧形涡流发生器前后的壁面平均努塞尔数,发现平均努塞尔数大幅提升,最大提升20%左右,且其沿流向的变化趋势与湍流相干结构的发展演化一致。The vortex generator is a common passively enhanced heat transfer element,which is widely used due to its high cost performance.In this paper,for the square pipe with an arcshaped vortex generator,the Time-Resolved Particle Image Velocimetry(TRPIV)and the Large Eddy Simulation(LES)were used to analyze the characteristics of the induced coherent structure by the vortex generator in the turbulent flow and its effect on heat transfer enhancement.The statistical information of the turbulent characteristic quantities obtained by experimental studies shows the imprints of the hairpin vortex legs and low-speed streaks.The hairpin vortices and the Counter-rotating quasi-streamwise Vortices Pair(CVP)were extracted by the vortex identification criteria.It is found that these two different types of vortex structures coexist and interact with each other in the flow field induced by the arc vortex generator.With the evolution and development of the structures,their spanwise scales increase continuously.In order to study the relationship between turbulent coherent structures and heat transfer enhancement,the spatial distribution of the coherent structure and temperature gradient is analyzed by numerical simulation.It is noted that the distribution of the coherent structure and temperature gradient has good regional consistency,which reflects the influence and control of the turbulent coherent structure on heat transfer enhancement.By comparing the average Nusselt number before and after the installation of the arc-shaped vortex generator,it is found that the average Nusselt number increases significantly,up to about 20%.And the trend of the average Nusselt number’s change along the streamwise direction is consistent with the development and evolution of the coherent structure in turbulence.

关 键 词：弧形涡流发生器 湍流相干结构 温度梯度 强化换热 

分 类 号：O357.5[理学—流体力学]