Performance potential of gas foil thrust bearings enhanced with spiral grooves

The upscaling of turbomachinery using gas foil thrust bearings is limited because of their limited load capacity and the thermal issues linked with very thin film thickness. The improvement potential of spiral grooves manufactured on the top-foil of such bearings is investigated in terms of load capacity and drag torque for a wide range of ramp depth, compressibility number and bearing compliance. Multi-objective optimization of grooves parameters allows to identify a trade-off between the drag reduction and the load capacity improvement. In some cases, load capacity improvements reach nearly 70% or drag torque at equal load diminishes by 40%. However, the results suggest that the ultimate load capacity of the bearing is reduced compared to plain gas foil thrust bearings.