Power loss reduction for tilt pad journal bearings utilizing pad pockets and steps

Abstract

Tilting Pad Journal Bearing (TPJB) are ubiquitous in turbomachinery from small high speed compressors to large turbine generator sets. The TPJB's power losses increase with machine size and speed, reaching as high as 1–2 MW loss (equivalent power for about 1000 homes) per bearing, in a large turbine generator. This study presents a novel power loss reduction technique, inserting a pocket and step in the pads, to activate cavitation in the pocket while maintaining pad stability. The benefits are demonstrated via Thermo-Elasto-Hydrodynamic (TEHD) CFD simulations comparing results with and without these modifications. The novel approach shows power loss reductions up to −27% without a load capacity loss, while reducing required supply oil flow, and peak pad temperature.