国外文献 > 1.轴承 > 1. 基础理论与机制 > 承载与性能
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| 标 题： |
A Model for Tilting Pad Thrust Bearings Operating With Reduced Flow Rate—Do Benefits Outweigh Risks?
一种适用于低流量运行的倾盘式推力轴承的模型——收益是否大于风险？ |
| 作 者： |
Koosha, Rasool
Andrés, Luis San |
| 关键词： |
Bearings [轴承]
Temperature [ 温度] |
| 出版年： |
2022 |
| 期刊名： |
Journal of engineering for gas turbines and power: Transactions of the ASME
《燃气轮机与动力工程杂志：美国机械工程师协会会刊》 |
| 年卷期： |
2022, vol.144, no.2 |
| 摘 要： |
The literature on tilting pad thrust bearings (TPTB) calls for flow reduction as an effective means to reduce drag power losses as well as oil pumping costs. However, the highest level of flow reduction a bearing can undergo while maintaining reliable operation is a key question that demands comprehensive analysis. This paper implements a model into an existing thermo-elasto-hydrodynamic (TEHD) computational analysis tool to deliver load performance predictions for TPTBs operating with reduced flow rates. For bearings supplied with either a reduced flow or an overflow conditions, a sound model for the flow and thermal energy mixing in a feed groove determines the temperature of the lubricant entering a thrust pad. Under a reduced flow condition, the analysis reduces the effective arc length of a wetted pad until matching the available flow. Predicted discharge flow temperature rise and pad subsurface temperature rise from the present model match measurements in the archival literature for an eight-pad bearing supplied with 150% to 25% of the nominal flow rate, i.e., the minimum flow that fully lubricates the bearing pads. A supply flow above nominal rate increases the bearing drag power because the lubricant enters a pad at a lower temperature, and yet has little effect on a thrust pad peak temperature rise or its minimum film thickness. A reduced flow below nominal produces areas lubricant starvation zones, and thus the minimum film thickness substantially decreases while the film and pad's surface temperature rapidly increase to produce significant thermal crowning of the pad surface. Compared to the bearing lubricated with a nominal rate, a starved flow bearing produces a larger axial stiffness and a lesser damping coefficient. A reduction in drag power with less lubricant supplied brings an immediate energy efficiency improvement to bearing operation. However, sustained long-term operation with overly warm pad temperatures could reduce the reliability of the mechanical element and its ultimate failure.
关于倾盘式推力轴承（TPTB）的文献指出，降低流速是一种有效减少阻力功率损耗以及降低油泵成本的方法。然而，轴承在保持可靠运行的同时能够承受的最大流速降低程度是一个关键问题，需要进行全面分析。本文将一个模型应用于现有的热弹性流体动力学（TEHD）计算分析工具中，以对以降低流速运行的 TPTB 的负载性能进行预测。对于采用降低流速或溢流条件的轴承，一个可靠的模型来描述进油槽中的流体和热能混合情况，能够确定进入推力垫的润滑剂的温度。在降低流速的情况下，分析会将浸湿垫的有效弧长减小到与可用流速相匹配的程度。根据本模型预测的排出流体的温度升高和垫子内部的温度升高与档案文献中关于配备 150%至 25% 标称流量（即完全润滑轴承垫所需的最小流量）的八垫轴承的测量值相吻合。当供应流量高于正常水平时，会增加轴承的阻力功率，因为润滑剂在进入垫片时的温度较低，但对推力垫片的峰值温度上升或其最小油膜厚度影响甚微。低于正常流量的情况会导致润滑剂供应不足区域的出现，从而使最小油膜厚度大幅降低，同时油膜和垫片的表面温度迅速升高，导致垫片表面出现显著的热凸起。与以正常流量润滑的轴承相比，供应不足的轴承会产生更大的轴向刚度和较小的阻尼系数。供应的润滑剂减少会导致阻力功率降低，从而立即提高轴承运行的能源效率。然而，长时间持续运行时如果垫片温度过高，可能会降低机械元件的可靠性并导致其最终失效。 |
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