NACA翼型針狀鰭片對微流道熱沉之熱傳性能影響

Influence of NACA airfoil shaped pin fin on the heat transfer performance of a microchannel heat sink

吳坤達(KUN-DA WU)

指導教授 ： 翁輝竹

中原大學/工學院/機械工程學系/碩士(2022年)

https://doi.org/10.6840/cycu202201500

摘要

本論文完成針狀鰭片形狀對於開放式微通道散熱器性能之數值研究，主要探討鰭片在不同的截面幾何外型與攻角的改變，應用在開放式微通道散熱器內對流熱傳性能的影響。考慮NACA0012、NACA2412、NACA4412、NACA6412、長矩形及片狀矩形六種幾何形狀，在雷諾數200到800之間、攻角0o到20o之間，並利用計算流體力學分析其流場與熱場性能及分布情況。
首先，本研究使用ANSYS Fluent進行文獻驗證以及網格獨立性測試，結果顯示整體趨勢相當吻合先前文獻數值。再進一步探討不同幾何形狀的熱流場性能差異，數值模擬結果發現，流場擾動效應主導了散熱器整體的散熱能力，增加流體流速可以提升努賽爾數，而流道內結構會使流場混合更均勻也能效提高微流道的散熱能力。
在固定總表面積與熱通量下，努賽爾數隨著雷諾數和攻角增加而增加，片狀矩形鰭片的壓降增加量最小。在攻角為0o及雷諾數為800下，長矩形鰭片有最佳的對流熱傳效果，相對於無鰭片之微通道的努賽爾數提升127.64%。其中，NACA系列鰭片具有讓冷卻液較貼合鰭片表面流動的特性，也能夠觀察到在鰭片後緣處產生擾流，機翼型鰭片相比其他兩的幾何形狀壓降增加率較低。以綜合評估熱性能來看，使用NACA 6412做為微通道散熱器中針狀鰭片的幾何形狀是最佳選擇，最大性能指數(TPF)為1.37。

關鍵字

NACA翼型 ； 微流道 ； 針狀散熱鰭片 ； 熱性能 ； 數值模擬

並列摘要

This study is conducted with the numerical study of the influence of pin fin shapes on the heat transfer performance of an open microchannel heat sink. The main focus is to investigate the effect of different cross-sectional geometry (NACA0012, NACA2412, NACA4412, NACA6412, rectangle, and plate) and angle of attacks (0o, 5o, 10o, 15o, and 20o) of the fins on the convective heat transfer performance in the heat sink. Reynolds number varies from 200 to 800. Analysis of the convective heat transfer performance and pressure distribution of flow and thermal fields using Computational Fluid Dynamics (CFD).
In the beginning, this study is carried out for current study models numerical verification and grid independence test using ANSYS Fluent. The numerical simulation results show that the overall trend is quite consistent with the previous literature values. The flow field vorticity effect dominates the overall thermal performance of the heat sink. Increasing the flow velocity and the structure inside the flow channel will make the flow field perturbation more evenly and also effectively improve the heat cooling capacity.
It is found that under the condition of uniform heat flux and the same specific surface area, the Nusselt number increases with increasing Reynolds number and angle of attack. However, the rectangle fin has the best convection heat transfer efficiency. The Nusselt number in attack angle 0o and Reynolds number 800 is 127.64% higher than the heat sink without fins. The plate-fin has the smallest pressure drop increase. The NACA series fins have the characteristic of allowing the cooling fluid to flow more closely to the surface of the fin and can generate a little vortex disturbance at the trailing edge of the fins, resulting in a lower pressure drop increase rate. In terms of overall thermal performance, NACA 6412 is the best choice with a maximum performance index (TPF) of 1.37.

並列關鍵字

NACA airfoil ； Microchannel ； Pin-fin heat sink ； Thermal performance ； Numerical somulation

參考文獻

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