Study of Static Performance Characteristics of Offset-Pressure Dam Bearing Considering Turbulent and Adiabatic Thermal Effects

As there is an increasing demand for high-performance turbo-machinery, hydrodynamic bearings are expected to run at high surface speed (>100 m/s) and heavy load (>4 MPa) operating conditions. Especially, high-speed and high-power gearboxes operate at such severe operating conditions for gas or steam turbine power generation applications. Conventionally, fixed profile bearings such as pressure dam or offset bearings are used in these gearboxes. However, they have design limitation on maximum surface speed due to stability requirements at no load conditions and maximum oil film temperature at heavy load and high-speed conditions. In this paper, it is attempted to combine the offset design feature “preload” with pressure dam bearings to see that if the operational design limits could be improved. The governing mathematical model includes turbulent and adiabatic thermal effects. The static performance characteristics of combined offset pressure dam bearings are compared with individual bearings. The analytical study found that combined offset pressure dam bearing delivers better performance than the other bearings. Also, the analytical model is validated with published experimental results.