2017 Volume 52 Issue 3 Pages 360-368
The purpose of this study is to elucidate effects of manufacturing errors on static and dynamic characteristics of multi-lobe hydrodynamic journal bearings. The study is also intended to come up with a proposal for guidelines about the optimized design for multi-lobe hydrodynamic journal bearings. This paper analyzed and examined changes in the dynamic characteristics of a four-lobe hydrodynamic journal bearing, such as oil film spring coefficients and oil film damping coefficients between the bearing and journal, and the stability characteristics of a rotor supported by bearings when the position of the bottom lobe at the sliding surface is shifted from where it should be due to manufacturing errors. The main results of the study show that when the position of the bottom lobe is moved inside of the bearing from the original location due to manufacturing errors, the dimensionless stability threshold speed becomes greater in comparison with the situation in which the lobe stays at the original location. On the other hand, manufacturing errors should not cause a shift in the position of the bottom lobe in outer direction of the bearing from the original location, and this should be included in design guidelines for four-lobe hydrodynamic journal bearings.
