CIESC Journal ›› 2016, Vol. 67 ›› Issue (5): 1814-1821.DOI: 10.11949/j.issn.0438-1157.20151623

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Enhanced heat transfer mechanism of winglet vortex generator in helical channel with semicircular cross section

LI Yaxia1, ZHANG Teng1, ZHANG Chunmei1, ZHANG Li2, WU Jianhua1   

  1. 1 College of Energy and Power Engineering, Shenyang University of Chemical Technology, Shenyang 110142, Liaoning, China;
    2 College of Chemical Engineering, Shenyang University of Chemical Technology, Shenyang 110142, Liaoning, China
  • Received:2015-10-30 Revised:2015-12-16 Online:2016-05-05 Published:2016-05-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51506133), the Foundation of Liaoning Educational Committee (L2014165) and the Doctoral Science Research Foundation of Liaoning Province (20141085).

翼型涡发生器对半圆形螺旋通道的换热强化机理

李雅侠1, 张腾1, 张春梅1, 张丽2, 吴剑华1   

  1. 1 沈阳化工大学能源与动力工程学院, 辽宁 沈阳 110142;
    2 沈阳化工大学化学工程学院, 辽宁 沈阳 110142
  • 通讯作者: 吴剑华
  • 基金资助:

    国家自然科学基金项目(51506133);辽宁省教育厅一般项目(L2014165);辽宁省博士科研启动基金项目(20141085)。

Abstract:

The purpose of this paper is to obtain the enhanced heat transfer characteristic of the winglet vortex generator (VG) in the helical channel with semicircular cross section. The shape and layout of the VG are concerned. CFD software is adopted to simulate the fluid flow and heat transfer characteristic in the smooth helical channel and that installed with four kinds of winglet vortex generator. The four styles of vortex generator are characterized as jxjs, jxjk, sjjs and sjjk VG, respectively. The simulated data coincide well with the experimental data. The results based on the current research show that after installing the vortex generator, the average ratio of Num to Nu0 is in the range of 1.044—1.074 where Num is the surface average Nusselt number of helical channel within the scope of ±180o away from the vortex generator and Nu0 is the corresponding value of smooth helical channel. However, the specific value between the flow resistance coefficient of helical channel with VG and the corresponding value of smooth channel, i.e. f/f0 is in the range of 1.105—1.188. The rectangular winglet VG is superior to the triangular winglet VG only in terms of heat transfer enhanced. Along with the flow direction, the convergent layout of VG is superior to the divergent layout for heat transferring. Based on the field synergy principle, the secondary flow field structure would be changed by the vortices shedding from the VG. Thus, the cooperativity of flow and temperature fields would be better and the heat transfer would be improved. For the helical channel with rectangular and triangular winglet VG, the compound secondary flow fields are four vortices and two large vortices, respectively, and the length of heat transfer effect is 10.47 and 12.56 times of winglet height, respectively.

Key words: helical channel, winglet vortex generator, heat transfer, flow, numerical simulation, field synergy

摘要:

为考察不同形状和布置方式的翼型涡发生器强化半圆形截面螺旋通道的换热特性,对单一以及安装了jxjs、jxjk、sjjs和sjjk 4种涡发生器的螺旋通道内流动与换热特性进行了数值研究,数值模拟结果与实验结果吻合较好。结果表明,研究范围内涡发生器前后180°范围内的换热壁面平均Nusselt数与单一通道的相应值之比的平均值在1.044~1.074之间,流动阻力系数f/f0在1.105~1.188之间。对传热效果而言,矩形翼优于三角形翼,对翼渐缩布置优于渐扩布置。涡发生器产生的纵向脱落涡旋改变了原有的二次流场结构,改善了速度场和温度场的协同性,强化了传热。安装jxjs和sjjs型涡发生器的复合二次流场分别为4涡和2个大涡结构,Re=8000时两者在通道内强化换热作用范围分别可达10.47和12.56倍翼高的距离。

关键词: 螺旋通道, 翼型涡发生器, 传热, 流动, 数值模拟, 场协同

CLC Number: