TRANSIENT THERMOELASTOHYDRODYNAMIC STUDY OF TILTING-PAD JOURNAL BEARINGS UNDER DYNAMIC LOADING

Nowadays, tilting-pad journal bearings are submitted to more and more severe operating conditions. The aim of this work is to study the ther mal and mechanical behavior of the bearing during the transient period from an initial steady state to a final steady state (periodic). In o rder to study the behavior of this kind of bearing under dynamic lendi ng (F-dyn) due to a blade loss, a nonlinear analysis, including local thermal effects, realistic boundary conditions, and bearing solid defo rmations (TEHD analysis) is realized. After a comparison between theor etical results obtained with four models (ISO, ADI, THD, and TEHD) and experimental data under steady-state operating conditions (static loa d W-s), the evolution of the main characteristics for three different cases of the dynamic load (F-dyn/W-s < 1, F-dyn/W-s = 1 and F-dyn/W-s > 1) is discussed. The influence of the transient period on the minimu m film thickness, the maximum pressure, the maximum temperature, and t he shaft orbit is presented. The final steady state is obtained a long time after the appearance of a dynamic load.