渦流產生器對微流道流體行為影響之研究

A Study on the Flow Behavior for Microchannel with Vortex Generators

邱奕郎(Yi-Lang Chiu)

指導教授 ： 鄧治東

中原大學/工學院/機械工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000653

摘要

摘 要
本論文以實驗及數值模擬的方式，探討於矩形微流道內配置矩型翼渦流產生器，並且改變矩型翼渦流產生器的攻角、對數及流動方向等參數對其流體行為之影響，於實驗的部分，分別進行7種不同試片的壓降量測，其主要流體工作介質為去離子水，雷諾數範圍介於45~455之間。經由模擬壓降值與實驗壓降值對比驗證，其結果顯示，平均誤差為4.1%，最大誤差為8%。由實驗結果可知，於微流道中配置矩型翼渦流產生器會使壓降值增加，其VG 1個案增加16~39%，VG 2個案增加24~71%，VG 4個案增加27~47%，VG 5個案增加32~78%，VG 6個案增加29~36%，VG 7個案增加8~16%；由數值模擬流場分析結果可知，流體流經矩型翼渦流產生器後由於擾動會產生低速尾流區，並且隨著雷諾數增加尾流區會有渦流的現象產生，並且渦流會隨雷諾數與攻角增加而變大，尾流也會隨著雷諾數與攻角增加而拉長. 當雷諾數達到366時，尾流長度可達4.6 mm。

關鍵字

矩型微流道 ； 流體特性 ； 矩型翼渦流產生器

並列摘要

Abstract
In this paper, experiments and numerical simulations were conducted to evaluate the influences of variation of locations, attack angles and the number of pairs of rectangular winglet longitudinal vortex generator (RWLVG) on flow characteristics in the rectangular microchannels. The pressure drops of seven different types of RWLVG in rectangular microchannels were measured experimentally. Deionized water was used as working fluid and the experimental Reynolds number varied from 45 to 460. The results obtained from numerical simulations were validated by the results obtained from the experimental data and these sets of results were in agreement; the average deviation of friction factor between numerically simulated results and experimental data is 4.1%, and the maximum deviation is 8%. According to the results obtained from the experiments, rectangular microchannels with RWLVG have larger pressure drop than those obtained from using the smooth rectangular microchannel. Compared with the pressure drop of smooth rectangular micro-channel (VG 3﹐the base case) at the same mass flow rate, on the average the pressure drop for case VG 1 averagely increases 16~39%; case VG 2 increases 24~71%; case VG 4 increases 27~47%; case VG 5 increases 32~78%; case VG 6 increases 29~36%; and case VG 7 increases 8~16%. As indicated by the flow field of numerical simulation, a wake region was generated at the trailing edges of RWLVG. Increasing Reynolds number, vortices appear in the wake region. And the vortices will be larger and the wake region will be longer while augmenting the Reynolds number and attack angle increase. When the Reynolds number reaches 366, the length of wake region extends to 4.6 mm.

並列關鍵字

rectangular microchannel ； rectangular winglet longitudinal vortex

參考文獻

[1] P. Chu, Y.L. He, Y.G. Lei, L.T. Tina, and R. Li, “Three-dimensional numerical study on fin-and oval-tube heat exchanger with longitudinal vortex generators,” Applied Thermal Engineering, vol. 29, pp. 859-876, 2009.

[2] A. Joardar and A. M. Jacobi, “Heat transfer enhancement by winglet-type vortex generator arrays in compact plain-fin-and-tube heat exchangers,” International Journal of Refrigeration, Vol. 31, pp. 87-97, 2008.

[3] Chunhua Min, Chengying Qi, Xiangfei Kong, and Jiangfeng Dong, “Experimental study of rectangular channel with modified rectangular longitudinal vortex generators,” International Journal of Heat and Mass Transfer, Vol 53, pp. 3023-3029, 2010.

[4] Qiuwang Wang, Qiuyang Chen, Ling Wang, Min Zeng, Yanping Huang, and Zejun Xiao, “Experimental study of heat transfer enhancement in narrow rectangular channel with longitudinal vortex generators,” Nuclear Engineering and Design, Vol. 237, pp. 686-693, 2007.

pp.346, 1995.