- 學位論文
海爾貝克陣列用於磁流體動壓軸承的穩定性分析研究
Stability Analysis of a Ferrofluid Hydrodynamic Journal Bearing System with Halbach Array Magnetic
摘要
近年來流體潤滑軸承在旋轉機構中的使用越來越廣泛，不過流體動壓軸承在運作過程中必會產生不穩定現象，如油漩、油顫等等，這些現象會造成軸承之間的碰撞與摩擦，使機台損壞壽命降低等後果。因此本研究將針對流體動壓軸承的不穩定現象提供最佳化方法，以磁流體代替傳統潤滑液並在外部設置海爾貝克陣列磁場，藉由磁流體在磁場下的特性提高油膜不穩定發生的頻率，使旋轉機構能避免在共振區下做運轉。 在本論文中，將成功建立一組流體動壓軸承轉子測試平台，其中以磁流體作為軸承潤滑液，並在外部設置一般環形排列磁鐵以及海爾貝克陣列磁鐵，藉由磁路和磁力大小分析觀察此兩種對於油軸承油旋、油顫等實驗之影響比較。最後由油軸承全頻譜串聯圖中觀察軸承發生油漩的穩定門檻轉速可得知，因為磁場可改變磁流體黏滯係數並提高軸承潤滑液剛度，進而提高油旋、油顫等不穩定現象發生頻率。實驗結果顯示，海爾貝克陣列磁場的效果最好，可有效將原始的油漩、油顫不穩定門檻每分鐘2940轉提高到4140轉。
並列摘要
Nowadays,the fluid-lubricated bearing applying in the rotating machines are very widespread. However some instability phenomenas ,such as oil whip and oil whirl, will appear when the fluid-lubricated bearing is working. These phenomenas will make bearing vibrating and decrease life of machine. Against to solve this problem, the research propose a solution to optimization the instability phenomenas. We use ferrofluid replace used lubrication,and set Halbach array magnetic field to change ferrofluid characteristic to increase the frequencies of fluid-induced self-excited vibrations. So that the rotor system can prevent working in resonance frequencies. First, this research will build a fluid-dynamic bearing rotor test platform. Using ferrofluid as lubrication ,and set a general annular array magnetic and a Halbach array magnetic outside. Second, through observed different magnetic directions effect on oil whip and oil whirl. Finally, we can found the oil whip and oil whirl appear frequencies obviously increase by full spectrum cascade plots with Halbach array magnetic. The speed of fluid-induced self-excited vibrations is increased from 2940rpm to 4140rpm.