含新型橢圓形溝槽之液體動壓軸承分析

Analysis of Hydrodynamic Journal Bearings with Novel Elliptical Groove

陳建佑(Chien-Yu Chen)

指導教授 ： 顏瑞和

國立臺灣大學/工學院/機械工程學研究所/博士(2010年)

https://doi.org/10.6342/NTU.2010.00065

摘要

本文提出一種新的橢圓溝槽設計，以改善傳統含人字形溝槽頸軸承的性能。文中的第一部分，先以寬頻元素法為基礎，發展可求解含人字形溝槽頸軸承的壓力分佈與動態係數的數值程式。程式中考慮了溝槽與溝岸交接的界面，以質量守恆處理液膜不連續的問題。此外，程式擁有可處理溝槽為曲線形狀的彈性。結果顯示，程式解出的負載，比其他文獻的數值結果更準確。當空蝕現象發生時，採用溝槽不連續的質量守恆搭配Elrod算則處理空蝕現象，可以進一步改善在高偏心比之負載的準確度。
本文的第二部分。提出含橢圓溝槽之新形狀的軸承。並使用上述發展的數值程式，分析其性能。橢圓溝槽軸承的負載、穩定性、洩漏量與傳統人字形溝槽軸承比較，結果顯示，本文提出的橢圓形溝槽擁有高徑向力、高負載、和低洩漏量。接著，本文找出軸承運轉時，最佳化溝槽參數，使軸承有最大的徑向力。最後，本文比較人字形、四邊溝槽、八邊溝槽、及橢圓形溝槽軸承表面的負載分布。以說明橢圓形溝槽的設計，如何增加負載。橢圓形溝槽軸承在軸向的負載分布，較人字形溝槽軸承均勻。在軸承中央處較人字形溝槽低的負載，會被軸承兩端較高的負載抵銷，於是達到較人字形溝槽高的負載。
本文的最後一部分，將橢圓形溝槽應用於可反轉的軸承上，以改善可反轉人字形溝槽的負載，並以數值方法探討性能改善的程度。橢圓溝槽可反轉軸承的負載、穩定性、耗能與傳統人字形溝槽可反轉軸承比較。比較結果顯示，橢圓形溝槽可反轉軸承的負載較高，耗能較低。橢圓溝槽可反轉軸承的高壓區不只在正轉的壓力產生區，也在反轉需要的壓力恢復區產生。此外，比較人字形、及橢圓形溝槽可反轉軸承表面的負載分布。以說明橢圓形溝槽的設計，如何增加負載。最後，在徑向剛性係數為考量的最佳化參數之下，橢圓形溝槽可反轉軸承的穩定性比人字形溝槽可反轉軸承優異。

關鍵字

液體動壓軸承 ； 橢圓溝槽 ； 人字形溝槽 ； 空蝕現象 ； 穩定性 ； 寬頻元素法

並列摘要

A novel elliptical groove is proposed in this work to improve the performance of conventional journal bearings. Firstly, the present work utilizes the spectral element method to calculate the pressure distribution and dynamic coefficients of herringbone-grooved journal bearings (HGJBs), in which the thickness of the fluid film changes abruptly in the groove-ridge region. Conservation of mass is adopted to solve the problem. Additionally, the present method can be adopted for grooves with curvy geometry. It shows that for the case of HGJB, the numerical result by the present method is more accurate than the numerical results found in the literature. Furthermore, employing the present method with the Elrod’s algorithm can improve the accuracy of deriving loads of HGJBs when cavitation occurs.
In the secondary part of this work, the novel elliptical grooves are proposed. This work utilizes novel elliptical grooves on a journal bearing and analyzes the characteristics of the elliptical-grooved journal bearings (EGJB) numerically. Load capacity, stability parameter, and total side leakage of the EGJB are compared with those of the HGJB. The comparison shows that the introduced EGJB have higher radial force, higher load capacity, and lower side leakage than the conventional HGJB. The optimum geometrical parameters of groove of EGJB are investigated based on the maximum radial force. Finally, the load distributions of several grooved journal bearings are compared to elucidate how elliptical grooves enhance load characteristics. The load distribution along the axial direction in EGJB is more uniform than that in the HGJB. The low load near the bearing center for the EGJB may be offset by the load away the bearing center; thus, a higher total load capacity than that of HGJB is achieved.
In the end of this work, to improve the performance of the reversible rotation grooved journal bearing (Rev-HGJB), this work utilizes elliptical grooves on a reversible rotation journal bearing (Rev-EGJB) and analyzes its characteristics numerically. Load capacity, pressure distribution, power loss, and dimensionless radial stiffness of the Rev-EGJB are compared with those of the Rev-HGJB. The comparison shows that the introduced Rev-EGJB exhibits higher load capacity and lower power loss than the Rev-HGJB. A larger high pressure region in the Rev-EGJB than that in the Rev-HGJB is achieved not only in the pressure-generated region, but also in the pressure-restored region. Furthermore, the load distributions of the Rev-HGJB and Rev-EGJB are compared to elucidate how elliptical grooves enhance load characteristics. Ultimately, the radial stiffness of the Rev-EGJB compared with that of the Rev-HGJB with the optimum geometry is also shown to be greater; thus, the Rev-EGJB is more stable than the Rev-HGJB.

並列關鍵字

Hydrodynamic journal bearing ； Elliptical groove ； Herringbone groove ； Cavitation ； Stability ； Spectral element method

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