工學院: 機械工程學研究所指導教授: 馬小康李奕嶒Li, Yi-TsengYi-TsengLi2017-03-132018-06-282017-03-132018-06-282015http://ntur.lib.ntu.edu.tw//handle/246246/278359本研究係發展一提供雙向風量之壓電磁力連動風扇系統並應用於LED之熱管理。相較於前期研究所發展提供單向風量之壓電磁力連動風扇系統，本研究所發展之雙向壓電磁力連動風扇系統不僅可以驅動更多被動扇葉同時進行擺動帶動更多風量，還可以提供雙向的風向對雙熱源同時進行散熱。二無因次化散熱能力參數M_MFPA與M_(D-MFPA)定義於本研究當中分別用於評估其單向及雙向壓電磁力連動風扇相較於自然對流之熱對流係數之比值。 本研究首先探討雙向壓電磁力連動風扇系統之幾何形狀、複合式扇葉的設計對於頻率及振幅的影響，並針對其散熱性能的比較以找出最佳複合式扇葉的比例設計，根據實驗結果，當扇葉長度增加時，其振幅會隨之上升然其共振頻率會隨之下降，而其共振頻率下降趨勢與理論結果誤差為10.01%。在不同複合式扇葉比例的實驗結果中，可以發現增加複合式扇葉比例時，其系統共振頻率也會隨之下降，而相對地振幅因系統運作時，扇葉越大會使空氣阻力越大進一步導致其有極值存在，使得散熱能力有最佳化的複合式散葉比例，根據結果顯示在複合式扇葉設計當中，其複合比例0.2-0.55時，整個系統散熱效果可達最佳。 雙向壓電磁力連動風扇在LED燈具散熱方面，根據複合式扇葉比例之研究，並結合散熱鰭片的設計，發展一LED的散熱解決方案，並為進一步增進其系統散熱效果，本研究還針對風扇與散熱鰭片的位置進行最佳化，由實驗結果可知，當雙向壓電磁力連動風扇放置於〖x/S〗_l=0.5與〖y/S〗_h= 0.033時，其最佳化散熱能力M_(D-MFPA)可達3.57，另外，根據實驗結果，再藉由Buckingham π theorem建立無因次化公式，透過無因次化的關係式可進一步預測不同位置情況下其系統之散熱能力。 除此之外，為使壓電磁力連動風扇之散熱能力能藉由不同方法提升，本研究亦探討模組化設計對於壓電磁力連動風扇之影響，藉由導風罩幾何參數之設計，探討導風罩對於風扇散熱能力之影響，根據實驗結果可知，其導風罩的高度與長度縮小可提升其整體的散熱能力，結果顯示當開啟壓電磁力連動風扇時，其平衡時的無因次化溫度(T^*)可從0.76降至0.67。另外，並在扇葉前端利用的縮口設計(Nozzle design)探討其對風扇的影響，其根據結果顯示，當縮口角度為63.43°時，其M_MFPA可提升至2.57。This thesis developed a cooling device of the dual-sided multiple fans system with a piezoelectric actuator (D-MFPA), which is able to drive eight passive vibrating fans and provide two-directional air flows by using only one piezoelectric actuator. The geometric effects of the D-MFPA and two types of the fan designs, viz. magnetic fan (MF) and composite magnetic fan (CMF) were also explored. In the investigation of the MF, the results indicated that the resonance frequency of the D-MFPA increased from 27.6 Hz to 66 Hz as the length of the carbon fiber plate (L) decreased from 55 mm to 35 mm. It also decreased the amplitude of the D-MFPA from 12.4mm to 4.8 mm. For CMF, the results showed that the resonance frequency decreased when the length of the Mylar plate (E_l) increased, and the maximum decrease was from 66 Hz to 45 Hz when L= 35 mm and E_l= 30 mm. M_MFPA and M_(D-MFPA) were defined to describe and quantify the improvement in the thermal performance as the one-sided and dual-sided multiple fans were applied for cooling, respectively. The results showed that the optimal M_(D-MFPA) of single piezoelectric fan was 1.58 for cooling one heat source. By contrast, under the same power consumption, the D-MFPA not only cooled two heat sources but also displayed better thermal performance; moreover, the CMF design in the D-MFPA system should be applied in the D-MFPA and the range of E_l/L was controlled at 0.22-0.50 to attain better thermal performance. In the investigation of the D-MFPA in LEDs thermal management, the several horizontal orientations (〖x/S〗_l) and vertical orientations (〖y/S〗_h) were examined to investigate the effects of different arrangements and further improve the thermal performance of the D-MFPA. The results indicated that M_(D-MFPA) can be improved to 3.92 under the case of 〖x/S〗_l= 0 and 〖y/S〗_h= 0.033; however, the single piezoelectric fan can only improve M_(D-MFPA) to 2.82. To improve the thermal performance of the multiple fans system by different way, this thesis also investigated the effect of the housing design on the MFPA. The results indicated that the geometry of the housing can significantly influence the thermal performance of the modular MFPA. The airflow generated from the MFPA was concentrated when Z^* decreased from 2.5 to 1.25 at Y^*=0.917 and θ= 0°; the results showed T^* (t) decreased from 0.76 to 0.67. Moreover, under the case of Z^*= 1.25 and θ= 0°, T^* (t) further decreased from 0.67 to 0.60 when Y^* decreased from 0.917 to 0.417. To optimize the thermal performance of the modular MFPA, a nozzle was applied for concentrating airflow. The results showed an optimal value of M_MFPA of 2.57 when the nozzle angle (θ) was 63.43° under the case of Z^*= 1.25, Y^*= 0.417.5603173 bytesapplication/pdf論文公開時間: 2017/2/15論文使用權限: 同意有償授權(權利金給回饋本人)雙向壓電磁力連動風扇複合式扇葉LED燈具散熱能力最佳化無因次化分析模組化設計縮口角度D-MFPAcomposite magnetic fanLEDsthermal performanceoptimizationdimensionless analysismodule designnozzle anglethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/278359/1/ntu-104-F99522124-1.pdf