Thermo-Hydrodynamic Analysis of a Plain Journal Bearing on the Basis of a New Mass Conserving Cavitation Algorithm

Abstract

Accurate prediction of cavitation is an important feature in hydrodynamic bearing modeling. Especially for thermo-hydrodynamic modeling, it is crucial to use a mass-conservative cavitation algorithm. This paper introduces a new mass-conserving Reynolds cavitation algorithm, which provides fast convergence and easy implementation in finite element models. The proposed algorithm is based on a variable transformation for both the pressure and mass fraction, which is presented in the form of a complementary condition. Stabilization in the streamline and crosswind direction is provided by artificial diffusion. The model is completed by including a simple and efficient thermal model and is validated using the numerical values of a reference plain journal bearing experiment under steady-state conditions. In addition, a transient analysis is performed of a journal bearing subjected to a harmonic load. It is shown that the proposed cavitation algorithm results are in good agreement with the reference measurement results. Moreover, the algorithm proves to be stable and requires only a small number of iterations to convergence in the Reynolds-based finite element model.

Elastohydrodynamic lubrication of coated finite line contacts

“…The Reynolds equation, which is a convection-diffusion type equation, is strongly convection dominated in highly loaded situations and will thus exhibit superious oscillations in the solution when solved using a typical Galerkin formulation. 13 The inconsistent (non-residual based) artificial diffusion method is one of the oldest and simplest methods as it directly adds an artificial diffusion term to the Reynolds equation in regions where the solution is strongly convection dominated. In Habchi et al, 8 it was shown that the solution was not significantly affected with the use of isotropic artificial diffusion.…”

Towards Accurate Prediction of Unbalance Response, Oil Whirl and Oil Whip of Flexible Rotors Supported by Hydrodynamic Bearings

“…This approach, however, is not mass conservative and can therefore lead to inaccurate results, especially for thermal models where conservation of mass can be important [24]. Hence, in the third model, a mass conservative cavitation algorithm is used.…”

“…in which c f is a transformation coefficient that arises from a flow balance in the circumferential direction under the assumption of streamer cavitation; see Alakhramsing [24] for details. The physical pressure p can be calculated by:…”

“…At the axial ends of the film domain, the constant pressure boundary condition of Model 2 is replaced by a non-submerged boundary condition, which allows the flow to exit the domain, but prevents it from re-entering [24]:…”

“…The cavitation algorithm of Alakhramsing was proven to be computationally efficient and robust for THDsimulations [24] and was therefore selected over alternative mass conservative cavitation algorithms.…”