磁流體動壓軸承穩定性與磁場分析研究

Magnetic Field Analysis and Stability of a Hydrodynamic Journal Bearing System Lubricated with Ferrofluid

陳廷宇(Ting-Yu Chen)

指導教授 ： 范憶華

中原大學/工學院/機械工程研究所/碩士(2014年)

https://doi.org/10.6840/cycu201400882

摘要

流體潤滑軸承在旋轉機械領域的使用非常廣泛，但流體潤滑液會造成軸承在旋轉機構中，產生不穩定因素如油漩、油顫等等，造成軸承碰撞摩擦，使機械組件損壞。有鑒於此，本研究針對旋轉機械流體油膜產生流體不穩定現象提出以鐵磁流體取代傳統潤滑流體並外加磁場以改變提昇油膜不穩定之發生頻率以避免旋轉機械操作於共振區。
在本論文中，成功建立一組流體動壓軸承轉子測試平台，並以鐵磁流體作為軸承潤滑液，且在軸承外部外加上不同型式之磁場，藉由分析不同磁路方向，對油軸承油漩、油顫等實驗之影響。由油軸承之全頻譜串聯圖中觀察軸承發生油漩之穩定門檻轉速中可知，因為磁場可改變磁流體之黏滯係數，提高軸承潤滑液剛度提升可以改變流體引發的油漩或油顫不穩定發生之頻率。實驗結果顯示，磁場設計為八極閉迴路環型磁場所獲得之效果為最優，可有效提升本測試平台之旋轉油軸承的油漩或油顫不穩定門檻發生之轉速由原始之3024轉提高到4480轉赫茲。

關鍵字

流體動壓軸承、鐵磁流體、軸承潤滑、油漩、油顫

並列摘要

Nowadays, the fluid fluid-lubricated bearings applying in the rotating machines are very widespread. However, these rotor interaction systems need to consider the instability phenomena induced by the lubricated fluid, such as the fluid whirl and fluid whip. The fluid-induced self-excited vibrations of rotor will make the journal rubbing or striking to bearing and may demand the machine parts. By these lights, the research proposed a solution to chance and promote the frequencies of fluid-induced self-excited vibrations by a ferrofluid and an additional magnetic field to avoid the rotating machine operating in the resonance frequencies.
In this research, we have established a fluid-dynamic bearing rotor test platform. The system uses the ferrofluid to replace traditional bearing lubricant fluid and provide different types of magnetic fields by the permanent magnets in the outside of bearing to change the lubricated viscously of ferrofluid. From the analyzing results of the different magnetic directions and the corresponding experimental results in the oil bearing system showed that the resonance frequencies of fluid whirl and fluid whip of the oil bearing system had been changed. The experimental results also showed that the magnetic field built by eight has the best performance in these proposed magnetic fields. It can promote the he instability threshold speed of the test system from 3024 RPM to 4480 RPM.

並列關鍵字

Fluid whip ； Fluid whirl ； Hydrodynamic Journal Bearings ； Ferrofluid ； Lubrication

參考文獻

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