微極性流體對具表面粗糙度步階軸承之效應分析

本文主要是要探討非牛頓微極性流體作用下之無限長二階步階軸承表面粗糙軸承的潤滑性能。微極性流體對軸承的性能影響，將採用Eringen理論模式，表面粗糙狀態採用Christensen隨機粗糙度模式，導出縱向及橫向粗糙度的隨機修正雷諾方程式，進而以數值模擬分析步階軸承受到微極性流體和表面粗糙度對潤滑性能之複合效應的影響，並以解析方法求出動態擠壓薄膜之壓力分佈，進一步計算出在不同微極性效應、粗糙度參數、形狀參數和步階軸承位置參數之情況下，對液動擠壓薄膜壓力、負載能力、負載中心和反應時間等軸承潤滑性能的影響。研究結果顯示，相較表面光滑軸承，橫向粗糙度所建立之壓力分佈P較高，因此其所能承受之負載能力W也相對較高，同時，橫向粗糙度會使得軸承的負載中心L_c向出口處偏移，增加軸承的反應時間τ。另一方面，微極性流體和流體特性長度，也會提高軸承之負載能力。隨著二段式步階軸承位置變化參數B_1的增加，步階軸承的負載能力逐漸降低。隨著膜厚參數h_m的增加，反應時間快速的降低，因此為避免步階軸承的損壞，h_m不可小於0.6。

關鍵字

微極性流體；表面粗糙度； Christensen隨機粗糙度模式

並列摘要

In this research, the infinite long two dimensional step journal bearing with surface roughness lubricated by non-Newtonian micro polar fluids was study. We adopted Eringen theoretical model to simulate the characteristics of micro polar fluid, and Christensen stochastic model to depict the surface roughness. With the basics of these two, we can deduce the longitudinal and transverse surface roughness modes of modified Reynolds Equation. Utilized numerical simulation scheme to solve these modified Reynolds equation, we can analyze the combined performance effects of micro polar fluids to step journal bearing with surface roughness. The distributed film pressure was obtained first, then, with different micro polar effect, roughness parameters, form parameters and position factor of step journal, the static film pressure, loading capacity, center of loading and response time were investigated. According to the results, with respect to smooth bearing, the transverse mode can build up a higher distributed pressure P and loading capacity W, meanwhile, the response time τ of journal bearing increases for transverse mode. As to the center of loading L_c, it will offset to the exit part of journal bearing. On the other hand, micro polar fluids and characteristic length of fluid can enhance also the loading capacity of bearing. Increasing the position factor B_1 of step bearing, decreasing the loading capacity it can afford. As the film parameter h_m increases, the response time decreases quickly, thus, to avoid the damage of step bearing, the thickness h_m cannot less than 0.6.

並列關鍵字

micropolar fluid ； surface roughness ； Christensen stochastic roughness model

國際替代計量

微極性流體對具表面粗糙度步階軸承之效應分析

全文下載

主題瀏覽