臺灣大學: 機械工程學研究所馬小康蘇?欽Su, Hsien-ChinHsien-ChinSu2013-04-012018-06-282013-04-012018-06-282012http://ntur.lib.ntu.edu.tw//handle/246246/256323本研究係針對多重擺動風扇冷卻系統進行效能分析與設計應用，本系統共有五片風扇，包括一片壓電風扇與一片磁力風扇，在風扇共振效應與磁鐵互斥力的交互作用下，本系統僅使用一片壓電片便可使五片風扇同時產生擺動，擺動的風扇會產生強制對流並增強散熱效果。本研究首先進行單片壓電風扇冷卻系統之風扇在散熱鰭片中的最佳擺放方式與適當運作情況測試，主要對其震動頻率、震幅、角度、水平位置、垂直位置、消耗功率及兩個無因次數"Ri (Gr/" 〖〖"Re" 〗_"PZT" 〗^"2" )與 M_p 進行討論，而較難觀察的流場，則以CFD-RC進行3D模擬來確定風扇擺動時周圍的流場情形。在決定最佳擺放方式與適當運作情況後，再將此結果運用於多重擺動風扇冷卻系統之設置。 多重擺動風扇冷卻系統之效能可由風扇震幅與散熱能力討論，因為風扇擺動時所製造的氣流強度與其震幅有正相關，又本系統共有五片風扇存在，所以可以利用此五片風扇之震幅總合來估計氣流強度。實驗結果顯示，在消耗功率同為0.03 W時，多重擺動風扇冷卻系統的五片風扇，其震幅總合為32 mm，而單片壓電風扇冷卻系統之震幅只有8 mm。本系統亦可與散熱鰭片(finned heat sink)進行結合以進行散熱效果的測試，本研究使用一20 W熱源對一散熱鰭片進行加熱，並以多重擺動風扇冷卻系統對其進行冷卻，實驗結果顯示，在穩態時，散熱鰭片表面溫度為67 ℃，當多重擺動風扇冷卻系統於36.4 Hz、50 V狀況運作十分鐘後，散熱鰭片表面溫度降低至50 ℃，且消耗功率只有0.03W。This research presents the performance and the applications of a multiple-vibrating fan cooling system composed of one piezoelectric (PZT) fan and four magnetic fans. The system takes advantage of both the resonant effect and the magnetic repulsive force to make five fans vibrate simultaneously by using one PZT plate. The vibrating fans are able to generate forced convective flow and enhance the cooling ability of the fan cooling system. The work first investigates the optimum arrangement and the suitable operating conditions of a single PZT fan cooling system. The effects of the operating frequency, the fan amplitude, the fan arrangement, the power consumption and the dimensionless PZT-convection number (M_p) and "Ri (Gr/" 〖〖"Re" 〗_"PZT" 〗^"2" ) have been analyzed. Further, a three-dimensional model has been built by using CFD-RC to account for the flow field around a vibrating fan. The results can be applied to a multiple-vibrating fan cooling system. The performance of a multiple-vibrating fan cooling system can be demonstrated by the fan amplitude and the cooling ability. Because the system is composed of five fans whose amplitudes are each proportional to the generated flow rate, the total amplitude of the fans can be used to estimate the flow rate of the five-fan system. The experimental results show that the total amplitude of the multiple-vibrating fan cooling system is 32 mm at a power consumption of 0.03 W. However, the amplitude of the single PZT fan cooling system is only 8 mm at the same power consumption. The system was embedded into a heat sink heated by a 20 W dummy heater. The temperature of the heat sink surface was maintained at 67 ℃ in a steady state. After turning on the system for 10 minutes under the conditions of 36.4 Hz and 50 V, the heat sink surface dropped from 67 ℃ to 50 ℃ at a power consumption of 0.03 W.3735285 bytesapplication/pdfen-US壓電風扇冷卻強制對流Piezoelectric fancoolingforced convectionthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/256323/1/ntu-101-D96522037-1.pdf