Transient Analysis of Plain and Tilt Pad Journal Bearings Including Fluid Film Temperature Effects

Abstract

The paper considers vibration response of spinning shafts supported by flexible fluid film bearings to sudden mass imbalance (blade loss). A time transient study of the plain journal bearing with thermal effects is performed. A comparison between three transient analyses is performed. The three transient analyses studied are, the full nonlinear analysis, linear analysis using dynamic coefficients, and pseudo transient analysis using static application of dynamic loads. The validity of the nonlinear transient analysis is checked by matching the lower unbalance results with the linear analysis and the static equilibrium position results with Newton-Raphson iterative scheme. A nonlinear transient analysis of the tilt pad journal bearing is also performed, and a comparison is drawn between the three approaches.