Transient rotordynamic thermal bow (Morton effect) modeling in flexure-pivot tilting pad bearing systems

The Morton effect (ME) is a thermally induced rotodynamic instability problem frequently reported in the fluid film bearing system. The temperature difference across the journal circumference may cause large spiral, syn-chronous vibration. Earlier ME modeling approaches rarely focus on the flexure-pivot bearing (FPB), signifi-cantly disproportionate to its wide application. Hereby, the transient ME prediction algorithm is proposed based on a high-fidelity thermo-elasto-hydrodynamic FPB model. A hybrid finite element analysis is adopted to eval-uate the entire rotor thermal bow profile including the rotor midspan. The algorithm is benchmarked with ex-periments and applied to a realistic compressor model. Simulations confirm the proneness of the FPB system to the ME instability, and reveal the ME sensitivity to the bearing-rotor configuration and operation conditions.