CFD simulation

The research field of the oil flow behavior of rolling bearings and the high-resolution determination of flow processes/phenomenological effects and the possible determination of hydraulic losses in rolling bearings is still very young. Nevertheless, fundamental investigations have already been carried out in this area at the ITR. This has involved both experimental investigations and simulations using special CFD techniques. The work to date has focused on the creation of design guidelines for the oil supply of axial rolling bearings and the development of technical-mathematical models with which it is possible to determine the oil flow and hydraulic losses as a function of various influencing factors.

The operating condition of high-speed and highly loaded radial tilting pad bearings is influenced to a large extent by the flow in the oil supply area. In particular, the convective heat transfer between the oil and the segments and the pressure build-up in front of the segments have a significant influence on characteristic bearing parameters.

While bearing calculations based solely on Reynold's differential equation do not take into account the flow outside the lubrication gap, a calculation based on the Navier-Stokes equations allows the system boundary to be further defined and the oil supply to be resolved in detail. The local temperature distribution in the entire bearing can be precisely determined by a coupled solution of the heat conduction equation. The extremely thin thermal boundary layers due to the Prandtl numbers pose special challenges when generating the calculation grids. The transitional turbulence occurring in parts of the flow area requires the additional solution of suitable turbulence models.

At the ITR, coupled flow simulations of plain bearings with conjugate heat transfer are carried out as part of research projects and verified by tests on the institute's own high-performance plain bearing test rig. The research results are incorporated into new calculation methods for industrial practice.