TU Darmstadt / ULB / TUbiblio

Numerical and Experimental Investigations on Preload Effects in Air Foil Journal Bearings

Mahner, Marcel and Li, Pu and Lehn, Andreas and Schweizer, Bernhard (2017):
Numerical and Experimental Investigations on Preload Effects in Air Foil Journal Bearings.
In: Journal of Engineering for Gas Turbines and Power, ASME, pp. 032505-1-032505-9, 140, (3), ISSN 1528-8919, DOI: 10.1115/1.4037965, [Article]

Abstract

A detailed elastogasdynamic model of a preloaded three-pad air foil journal bearing is presented. Bump and top foil deflections are herein calculated with a nonlinear beamshell theory according to Reissner. The two-dimensional pressure distribution in each bearing pad is described by the Reynolds equation for compressible fluids. The assembly preload is calculated by simulating the assembly process of top foil, bump foil, and shaft. Most advantageously, there is no need for the definition of an initial radial clearance in the presented model. With this model, the influence of the assembly preload on the static bearing hysteresis as well as on the aerodynamic bearing performance is investigated. For the purpose of model validation, the predicted hysteresis curves are compared with measured curves. The numerically predicted and the measured hysteresis curves show a good agreement. The numerical predictions exhibit that the assembly preload increases the elastic foil structural stiffness (in particular for moderate shaft displacements) and the bearing damping. It is observed that the effect of the fluid film on the overall bearing stiffness depends on the assembly preload: For lightly preloaded bearings, the fluid film affects the overall bearing stiffness considerably, while for heavily preloaded bearings the effect is rather small for a wide range of reaction forces. Furthermore, it is shown that the assembly preload increases the friction torque significantly.

Item Type: Article
Erschienen: 2017
Creators: Mahner, Marcel and Li, Pu and Lehn, Andreas and Schweizer, Bernhard
Title: Numerical and Experimental Investigations on Preload Effects in Air Foil Journal Bearings
Language: English
Abstract:

A detailed elastogasdynamic model of a preloaded three-pad air foil journal bearing is presented. Bump and top foil deflections are herein calculated with a nonlinear beamshell theory according to Reissner. The two-dimensional pressure distribution in each bearing pad is described by the Reynolds equation for compressible fluids. The assembly preload is calculated by simulating the assembly process of top foil, bump foil, and shaft. Most advantageously, there is no need for the definition of an initial radial clearance in the presented model. With this model, the influence of the assembly preload on the static bearing hysteresis as well as on the aerodynamic bearing performance is investigated. For the purpose of model validation, the predicted hysteresis curves are compared with measured curves. The numerically predicted and the measured hysteresis curves show a good agreement. The numerical predictions exhibit that the assembly preload increases the elastic foil structural stiffness (in particular for moderate shaft displacements) and the bearing damping. It is observed that the effect of the fluid film on the overall bearing stiffness depends on the assembly preload: For lightly preloaded bearings, the fluid film affects the overall bearing stiffness considerably, while for heavily preloaded bearings the effect is rather small for a wide range of reaction forces. Furthermore, it is shown that the assembly preload increases the friction torque significantly.

Journal or Publication Title: Journal of Engineering for Gas Turbines and Power
Volume: 140
Number: 3
Publisher: ASME
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute of Applied Dynamics (AD)
Date Deposited: 08 Nov 2017 15:11
DOI: 10.1115/1.4037965
Export:

Optionen (nur für Redakteure)

View Item View Item