Regularised cavitation algorithm for use in transient rotordynamic analysis

Abstract Journal bearings are still widely used, and – in combination with the omnipresent trend of light weight construction – there is an increasing focus on transient behaviour. Therefore, the structure, or more precisely, the aspect of rotordynamics has to be considered in conjunction with the hydrodynamics. Existing tools either address rotordynamics accurately while simplifying the bearings, or they model the bearings profoundly, including cavitation, but oversimplify the rotor to a point mass. The paper at hand addresses an approach to close the gap between both worlds. Therefore, a cavitation algorithm for the use in transient rotor dynamic applications is developed based on a regularised formulation of the Elrod–Adams model. Due to the achieved smoothness of the cavitation boundary, the solution of the hydrodynamic task yields to a more robust and faster calculation with respect to the classical approach. Therefore an application in transient simulations including rotor or multibodydynamic interactions under arbitrary conditions is realizable. For validating purposes, other approaches as well as experimental data were considered. The comparison shows an excellent agreement and additionally underlines the numerical advantages. As a result, the influences of rotordynamic aspects like the shaft's time dependent skew positioning can be considered and lead to a more precise representation of the system's behaviour, e.g. bearing damping or minimal fluid film gap.