Analysis of a tilting pad journal bearing to avoid pad fluttering

This paper describes the investigation into the static and dynamic performance of a tilting pad lightly loaded journal bearing. Some of the bearings were operating with some of the pads fluttering. The analysis of the bearings confirmed the likelihood of pad fluttering and so three possible means to overcome this phenomenon were investigated. Introducing a pad preload would require the installation of a number of shims into the bearing. Similarly, installing pad stops and/or springs introduced more working parts to each bearing. The third option of machining a leading edge taper or relief on each pad was deemed to be the better solution. The geometry of this relief (depth and length around the arc) was found to be an important design parameter. The larger the angular extent of the relief and the deeper it is were found to increase the oil flow rate, thereby reducing the operating temperature of the bearings. The direct stiffness of the bearing is improved by introducing a relief to the leading edge of each pad. Design changes were made to the actual bearings with a significant reduction in bearing operating temperature and wear.