摘要
冷卻風扇在 IT、汽車、工業和家用電器上是熱管理的關鍵部件。近年，高速計算和自動駕駛汽車之散熱需求急劇增加，使散熱風扇之性能比平時高。在高速旋轉下，散熱風扇產生之噪音、結構變形和應力也值得關注。本研究使用有限元素分析探討風扇結構在高速運轉時產生之變形及應力。首先透過實驗模態分析驗證風扇之有限元素模型，在實驗中，加速度計之質量效應在風扇上是顯著的，應加入有限元素模型中考慮。接著對風扇模型進行結構分析，主要受離心力、空氣動力及熱效應之影響。分析結果說明，離心力引起的結構變形較空氣動力更顯著。熱是透過散熱風扇從伺服器上帶走，因此，伺服器之散熱風扇基本在40 °C至70 °C之溫度範圍運行，由材料之熱膨脹係數產生結構變形。此外，熱顯著的導致材料劣化，如楊氏係數對變形也產生貢獻。因此，分析結果表明離心力和熱是結構變形之主要貢獻因素，而空氣動力效應是微不足道的。
並列摘要
Cooling fan is a critical part to thermal management in IT, automotive, industry and home appliances. Recently, the demands for heat dissipation of high speed computation and autonomous vehicles are dramatically increased. The performance of cooling fan is higher than usual. Under high-speed rotation, the cooling fan generates noise, structure deformation and stress that are of concern. The purpose of this research is to investigate the deformation and stress of the fan structure using finite element analysis during high-speed rotation. Finite element model of the cooling fan is first validated using experimental modal analysis. In this experiment, mass effect of accelerometer on full fan is significant and should be taken into account in finite element model. Structure analysis is then conducted on the fan model, which is mainly affected by centrifugal force, aerodynamic force and thermal effect. Analysis results show that structure deformation caused by centrifugal force is much more significant than that of caused by aerodynamic force. Thermal is the matter to be removed from the server by cooling fan. Thus, a cooling fan of server is basically operating at the temperature range from 40 °C to 70 °C. Structure deforms due to the coefficient of thermal expansion of the material. Besides, thermal significantly leads to material deterioration, i.e. elastic modulus, which also contributes deformation. Consequently, the analysis results show that centrifugal force and thermal are the two main contributions to structure deformation and aerodynamic effect is trivial.