Dynamic load and thermal coupled analysis for the inter-shaft bearing in a dual-rotor system

The inter-shaft bearings are important supporting parts between higher and lower pressure rotors in dual-rotor systems, it is essential to analyze their temperatures during operation. This paper concentrates on the effect of the dynamics of the system on the temperatures of bearings, namely, the dynamic load is coupled with thermal behaviours. The dynamic load of the inter-shaft bearing is obtained by solving the dynamic equations of the system numerically. The friction heat generations (FHGs) under the dynamic load are obtained by Palmgren's empirical formula, based on which, the unsteady-state heat balance equations under the dynamic load are proposed considering the viscosity-temperature relationship of the lubricant. The steady-state and unsteady-state temperatures analysis of the inter-shaft bearing are carried out afterwards. The results show that the temperature of the inter-shaft bearing and the total FHG increase sharply and form two peaks in the "resonance zone" of the dual-rotor system, and gradually increase in the "non-resonance zone" of the system. The steady-state temperature of lower rotation speed in the "resonance zone" may be much higher than that of higher rotation speed in the "non-resonance zone". The load FHG plays a leading role in the "resonance zone", while the viscosity FHG plays a leading role in the "non-resonance zone".