壓電磁力連動風扇之模組化

The Study of Multiple Piezoelectric-Magnetic Fans Modularized

柯幸宜(Sing-Yi Ke)

指導教授 ： 馬小康

國立臺灣大學/工學院/機械工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10165

摘要

本研究係利用導風罩對壓電磁力連動風扇進行模組化的設計，由於先前已有非常多風扇相關參數的研究，例如最大的擺動幅度、共振頻率原理、葉片材料性質的選擇、葉片的間距，這些研究雖能使散熱效率有效提升，但卻仍有一個共同的缺點就是”風量不集中”，若能改善的話，壓電風扇將擁有更佳的散熱能力，因此本研究係針對導風罩的設計改善原有的缺陷。
本研究對導風罩定義相關無因次參數並進行溫降實驗，在整體消耗功率為0.2W共振頻率為46Hz的情況下，對15W的模擬熱源進行散熱，首先從結果中探討導風罩高度無因次參數(Z*)以及導風罩長度無因次參數(Y*)的影響，發現分別在Y*=0.417，Z*=1.25會有最低熱阻值4.45°C/Wm。由討論導風罩角度的影響發現，當導風罩設計之無因次參數為在Y*=0.417，Z*=1.25時，θ若由0度漸增，散熱效率便會增加，當角度增加至θ=64.43°時，會有最大散熱效率，而隨著θ的繼續增加，散熱效率便開始下降。最佳散熱效率出現在當Y*=0.417，Z*=1.25，θ=64.43°時，溫差值達到53.13℃，與無導風罩的設計比較下，散熱效率(η)可由33.45%提升至46.61%。
同時本研究也對導風罩進行數值分析與實驗在不同導風罩角度參數之結果比較，從模擬結果的流場中發現在θ=64.43°時，有最佳的分布以及最大的平均速度值，此分析結果與實驗值相符合。

關鍵字

壓電磁力連動風扇 ； 導風罩設計 ； 無因次參數

並列摘要

This study is aimed at improving the thermal efficiency of a modularized multiple fans-piezoelectric actuator (MFPA) system by a proper housing design. Previous studies showed that thermal performance of a MFPA system is influenced by investigation of the maximum vibration amplitude, resonance effect, material and the pitch ratio of fan. However, there still exists a common problem remaining unsolved, i.e., the air flow is not fully utilized. If the air stream can be properly guided and more effectively utilized, the thermal performance can be further improved. Thus, this study focuses on resolving this deficiency by a proper housing design.
By defining the dimensionless geometrical ratios of the housing design, experiments are properly designed and performed under the following operation conditions: power consumption of 0.2W with input frequency of 46Hz and heat source of 15W. Experimental results are presented and discussed in terms of the dimensionless length number (Y*), dimensionless width number (Z*), and the housing angle(θ). The result showed that the thermal efficiency η is improved to reach a maximum value near Y*=0.417, Z*=1.25 and θ=64.43° with a minimum thermal resistance of 4.45°C/W and a temperature reduction of 53.13℃. Compared with no housing design, the thermal efficiency η is improved from 33.45% to 46.61%.
Numerical simulation and analysis are also employed to study the nozzle angle effects. It is found that the flow configuration with a maximum average velocity appears nearθ=65°, which is consistent with the experiment results.

並列關鍵字

modularized multiple fans-piezoelectric actuator ； housing design ； dimensionless geometrical ratios

參考文獻

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