Lu Jia, Reddyhoff Tom, Dini Daniele
Tribology Group, Department of Mechanical Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ UK.
Tribol Lett. 2018;66(1):7. doi: 10.1007/s11249-017-0953-2. Epub 2017 Nov 27.
We present an infrared microscopy technique, capable of measuring the temperature of both the bounding surfaces and the oil film in an elastohydrodynamic contact. This technique can, for the first time, spatially resolve the oil film temperature in three dimensions. The contact is produced by loading a steel ball against a sapphire disc, and the film is viewed using an infrared microscope focussing through the disc. Two band pass filters are used to isolate the radiation from the oil film, and Planck's law is applied to data obtained at a known temperature as part of the calibration procedure. The proposed technique requires the emissivity of the oil film to be measured, which is acquired in situ and is shown to vary strongly as a function of thickness and temperature. The technique is validated under pure rolling conditions, when the temperature of the oil film is equal to the controlled lubricant reservoir temperature, and also compared to an equation commonly used to predict average film temperatures, confirming the value of the unknown constant. The technique is then used to gain insights into the thermal/rheological behaviour within a contact. This is important since the temperature of elastohydrodynamic contacts is critical in determining friction and hence the efficiency of machine components and this technique enables much needed validation and provides input data for CFD and numerical simulations.
我们提出了一种红外显微镜技术，它能够测量弹性流体动力接触中边界表面和油膜的温度。这项技术首次能够在三维空间上解析油膜温度。通过将钢球加载到蓝宝石盘上来产生接触，并使用透过盘聚焦的红外显微镜观察油膜。使用两个带通滤波器来分离来自油膜的辐射，并且在作为校准程序一部分的已知温度下获取的数据上应用普朗克定律。所提出的技术需要测量油膜的发射率，该发射率是在原位获取的，并且显示出随厚度和温度的变化而强烈变化。该技术在纯滚动条件下得到验证，此时油膜温度等于受控润滑剂储存器温度，并且还与通常用于预测平均膜温度的方程进行比较，从而确定未知常数的值。然后使用该技术深入了解接触内的热/流变行为。这很重要，因为弹性流体动力接触的温度对于确定摩擦进而对于机器部件的效率至关重要，并且该技术能够进行急需的验证，并为计算流体动力学（CFD）和数值模拟提供输入数据。
