IDENTIFICATION OF NUMERICAL SQUEEZE-FILM DAMPER MODELS FOR EFFICIENT AEROENGINE VIBRATION ANALYSIS

The accuracy of the dynamic analysis of rotor systems incorporating squeeze film damper (SFD) bearings is typically limited by a trade-off between the capabilities and the computational cost of the bearing model used. Simplified solutions to the Reynolds equation such as short and long bearing models, and their variants, while providing rapid solution, significantly restrict the general applicability of the solutions. Numerical solutions to the Reynolds equation allow its solution in full form, with a variety of boundary conditions. Solving the Reynolds equation numerically imposes a significant computational cost on the dynamical analysis, rendering it computationally prohibitive for industrial applications. To surmount this problem, the present paper develops the use of Chebyshev polynomial fits to mimic the hydrodynamic relationship obtained through the finite difference (FD) solution of the incompressible Reynolds equation. In order to overcome limitations of previous interpolation approaches, the proposed method has three features: (i) a reduced number of input variables with a clearly defined finite range; (ii) interpolation of the pressure rather than the bearing force; (iii) division of the pressure function into its static and dynamic parts. These manipulations allow for efficient and accurate identification in the presence of cavitation and the presence of the groove, feed-ports and end-plate seals. The ability of Chebyshev polynomials to rapidly reproduce results obtained using FD routines is demonstrated. The advanced bearing models developed are proven to give more accurate results than alternative analytical bearing models when compared to experimental results.