Comparison of the Steady-State and Dynamic Performance of Two Fixed-Geometry Journal Bearings

This paper evaluates two different journal bearings: a cylindrical bore plain journal bearing and a tri-lobe taper land bearing. Each bearing has the same nominal diameter (89mm) and aspect ratio (L/D = 0.7). The shaft rotational speed ranged from 6krpm to 14krpm and the bearing specific load from 700kPa to 2800kPa. The bearings’ steady-state performance is evaluated according to relative bearing and shaft displacement, bearing operating temperature and power loss. A frequency-domain analysis is used to determine bearing rotordynamic coefficients — it treats the bearing as a mass-spring-damper system. Excitation frequencies range between 20Hz and 350Hz. Ultimately, the tri-lobe taper land bearing offers better stability whereas the cylindrical bore plain journal bearing has a lower eccentricity and runs cooler for a given operating condition. The dynamic properties of the two bearings are found to be similar, although the higher stability of the tri-lobe taper land bearing is also reflected in the dynamic coefficients.Copyright © 2011 by Her Majesty The Queen in Right of Canada