Frequency Effects on the TEHD Behavior of a Tilting-Pad Journal Bearing Under Dynamic Loading

Abstract

In this paper, a theoretical nonlinear analysis of a tilting-pad journal bearing is presented when both a dynamic load and a static load are applied. This analysis is performed under TEHD regime which takes into account both thermal behavior and elastic deformations of the bearing. A comparison between numerical maximum journal amplitudes and experimental data in the case of synchronous dynamic loading is carried out in order to justify the TEHD analysis. The influence of the dynamic loading frequency, which can occur because of vibrations in a turbomachinery, will be studied at a constant rotational speed (15,000 rpm) and for a low (200 N) and a high (2652 N) rotating load and for a periodic dynamic load. It will be shown that, for a critical frequency, the amplitude of the shaft orbit is maximum and this changes the behavior of the tilting-pad journal bearing. It is apparent that the application of the dynamic load generates a thermal transient regime. The increase in the maximum bearing temperature is larger for high dynamic loading response. Consequently, the behavior of the bearing is mainly modified during the first few seconds when the loading frequency is near the critical frequency.