• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Thermal performance and flow behavior of winglets vortex generators in a circular tube
【24h】

Thermal performance and flow behavior of winglets vortex generators in a circular tube

机译：圆管中小翼涡流发生器的热性能和流动特性

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Various technologies have been developed to enhance heat transfer and ultimately to develop more efficient compact heat exchanging devices. Vortex generators/turbulence promoters generate vortices which reduce boundary layer thickness and yield a better mixing of the fluid to enhance heat transfer. Vortex generators (VGs) create longitudinal vortices which do not decay until further downstream and consequently increase heat transfer coefficient with comparatively lower pressure drop in this region. In this research, thermal performance of winglets longitudinal VGs is investigated experimentally and numerically. Delta winglet VGs of different heights, attack angles and arrangements are inserted inside a pipe of inner diameter D = 52 mm. Research with and without VGs is conducted for air flow within a range of Reynolds numbers 6000 to 33000 and a constant heat flux of 694 W/m 2 on the tube surface. The influence of the winglet VGs on thermal performance and pressure dissipation is investigated through Nusselt number and friction factor.;The objectives of the current research are to investigate the thermal performance enhancement compared with smooth tube and identify the parameter which induces the highest thermal performance augmentation in the circular tube. In order to understand the mechanism of heat transfer enhancements, details of the flow behavior are also investigated with the help of flow visualization experiment by employing high speed camera and smoke generator.;The experimental results indicate that Nu decreases with pitch ratio but increases with Re, attack angle, and blockage ratio. Nusselt number increment (Nu/Nu0) decreases with Re and pitch ratio but increases with blockage ratio and attack angle. The maximum Nusselt number achieved is 133.40 but the maximum Nusselt number increment (Nu/Nu0) is 1.98. The maximum friction factor is 0.13 while the maximum friction factor increment ( f/f0) is 4.88. Thermal performance enhancement (TPE) decreases with blockage ratio, attack angle, Re and pitch ratio, the largest TPE is 1.45. Hence, blockage ratio = 0.1 with pitch ratio = 2.4, attack angle = 0° and Re = 6000 is the best parameter for TPE. The simulation results indicate that the maximum Nusselt number is 118.59 but the maximum Nusselt number increment (Nu/Nu0) is 1.75. The maximum friction factor is 0.11 while the maximum friction factor increment (f/f0) is 3.2. The maximum TPE is 1.31. The best set of parameters for TPE is beta = 30°, B = 0.1, and Re = 6000.;Keywords: Heat transfer enhancement, heat exchanger, circular tube, winglets vortex generator, flow visualization, horseshoe vortex, longitudinal vortex.
机译：已经开发了各种技术来增强热传递并最终开发出更有效的紧凑型热交换装置。涡流发生器/湍流促进剂产生的涡流减小了边界层的厚度，并产生了更好的流体混合，从而增强了热传递。涡流发生器（VG）产生纵向涡流，涡流不会衰减，直到更下游，并因此以该区域相对较低的压降增加传热系数。在这项研究中，对小翼纵向VG的热性能进行了实验和数值研究。将不同高度，迎角和布置的三角翼小翼VG插入内径D = 52 mm的管道内。进行有无VG的研究，以研究雷诺数6000到33000之间的气流以及管表面的恒定热通量为694 W / m 2。通过Nusselt数和摩擦系数研究了小翼VGs对热性能和压力耗散的影响。在圆管中。为了理解传热增强的机理，还通过使用高速摄像头和烟雾发生器在流动可视化实验的帮助下研究了流动行为的细节。 ，攻角和阻挡率。 Nusselt增量（Nu / Nu0）随Re和螺距比而减小，但随堵塞率和攻角而增大。达到的最大努塞尔特数为133.40，但最大努塞尔特数增量（Nu / Nu0）为1.98。最大摩擦系数为0.13，而最大摩擦系数增量（f / f0）为4.88。热性能增强（TPE）随堵塞率，攻角，Re和螺距比而降低，最大TPE为1.45。因此，对于TPE，最佳的参数是阻塞比= 0.1，俯仰比= 2.4，攻角= 0°，Re = 6000。仿真结果表明，最大努塞尔特数为118.59，但最大努塞尔特数增量（Nu / Nu0）为1.75。最大摩擦系数为0.11，而最大摩擦系数增量（f / f0）为3.2。最大TPE为1.31。 TPE的最佳参数集是beta = 30°，B = 0.1和Re =6000。关键词：传热增强，热交换器，圆管，小翼涡发生器，流动可视化，马蹄涡，纵向涡。

著录项

  • 作者

    Xu, Yunbo.;

  • 作者单位

    The Petroleum Institute (United Arab Emirates).;

  • 授予单位 The Petroleum Institute (United Arab Emirates).;
  • 学科 Mechanical engineering.
  • 学位 M.S.
  • 年度 2016
  • 页码 144 p.
  • 总页数 144
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号