Improving Critical Speed Calculations Using Flexible Bearing Support FRF Compliance Data.

Rotor system of modern aero-engine together with the case mounted on the wing represents a uniform system that is supposed to be considered as a rotor-bearings-foundation structure. Nowadays rotating machinery such as modern aircraft engines usually designed, marketed and sold for the most part based on analytical and numerical predictions. In such a way methods to incorporate the foundation effect in rotordynamic calculations are very important. For investigation purposes a rotor-foundation test rig, which can simulate the aero-engine’s typical operating condition such as wing vibration and hard landing, was built to study the influence of foundation behavior on the dynamic characteristics of rotor system. To predict natural frequencies for the full system simplified models based on FEM approach were created. Moreover, simple numerical model was created to study influence of foundation kinematic excitation on behavior of rotor disk orbit. Furthermore simulation results were compared with experimental to understand influence of main parameters which define foundation vibration on rotor deviation from normal operation condition. Obtained numerical and experimental results can help to understand principles of rotating structure-foundation interaction when the later one subjected to excitation and could be further used for improving of more complicated models for design and enhancement of aircraft engines.

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Including the Effects of Flexible Bearing Supportsin Rotating Machinery

Vázquez

Barrett

Flack

2000

International Journal of Rotating Machinery

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Unbalance response and stability analyses of a flexible rotor on three lobe journal bearings on flexible supports are presented. The influence of the support structure was included in the analyses using polynomial transfer functions. These transfer functions were extracted from measured dynamic compliance data of the support structure, measured at the bearing locations. Numerical predictions using polynomial transfer functions and single mass supports are compared to the experimental data. Predictions using the transfer function representation of the support structure show a clear improvement over the predictions using single mass supports without over-complicating the problem. The predicted critical speeds are within 2.9% of the measured critical speeds. The predicted stability threshold agrees with the measured stability threshold within 1%. The effects of cross talk between supports and cross coupling between horizontal and vertical directions are investigated. The cross talk between supports was found to have a strong influence in the results while the influence of cross coupling between the vertical and horizontal directions is negligible.

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Improving Critical Speed Calculations Using Flexible Bearing Support FRF Compliance Data.

Cited by 12 publications

References 11 publications

Influence of Metal Rubber Ring on the dynamics of the Active Magnetic Bearing system for optimal performance

Influence of Metal Rubber Ring on the dynamics of the Active Magnetic Bearing system for optimal performance

Experimental Investigation and Numerical Analysis on Influence of Foundation Excitation on the Dynamics of the Rotor System

Including the Effects of Flexible Bearing Supportsin Rotating Machinery

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