Analysis of Turbulence and Convective Inertia in a Water-Lubricated Tilting-Pad Journal Bearing Using Conventional and CFD Approaches

ABSTRACT

The influence of turbulence and convective fluid inertia in a water-lubricated journal bearing was investigated using two types of models: a “conventional” solution based on traditional lubrication theory (Reynolds equation) and a more rigorous computational fluid dynamics (CFD) program containing a full Navier-Stokes solution. The calculations reveal that turbulence accounts for around 50% of the load capacity in the water-lubricated bearing studied, highlighting the importance of accurate characterization of turbulence in such applications. Convective inertia, also referred to as transport inertia because it depends only on the spatial parameters within the film rather than time-dependent journal motions, was found to lower the static film pressures (load capacity) by about 6% compared to an inertialess solution.

Hydrodynamic pressures calculated by the conventional Reynolds solution were initially about 30% lower than those of the more rigorous CFD model for the water-lubricated bearing operating in the turbulent regime. The mesh spacing of the conventional model was refined and a method was developed to adjust the turbulence model within the Reynolds solution as a function of the pivot Reynolds number. These refinements brought the calculated bearing load capacities and power losses of the conventional Reynolds model into better agreement with those of the CFD model for a broad range operating conditions.

KEYWORDS:

• Turbulent flow in hydrodynamics
• inertia effects in hydrodynamics
• tilting-pad bearing
• CFD bearing analysis
• water-lubricated bearing