Measured rotordynamic force coefficients (stiffness, damping, and added mass) and static characteristics (eccentricity and attitude angle) of a pressure-dam bearing are presented and compared to predictions from a Reynolds-equation model, using an isothermal and isoviscous laminar analysis. The bearing’s groove dimensions are close to the optimum predictions of Nicholas and Allaire (1980, “Analysis of Step Journal Bearings-Infinite Length and Stability,” ASLE Trans., 22, pp. 197–207) and are consistent with current field applications. Test conditions include four shaft speeds (, , , and ) and bearing unit loads from . Laminar flow was produced for all test conditions. A finite-element algorithm was used to generate solutions to the Reynolds-equation model. Excellent agreement was found between predictions and measurements for the eccentricity ratio and attitude angles. Predictions of stiffness and damping coefficients are in reasonable agreement with measurements. However, experimental results show that the bearing has significant added mass of about at no-load conditions, versus zero mass for predictions from the Reynolds-equation model and using Reinhardt and Lund’s (1975, “The Influence of Fluid Inertia on the Dynamic Properties of Journal Bearings,” ASME J. Lubr. Technol., 97, pp. 159–167) extended Reynolds-equation model for a plain journal bearing. The added mass quickly drops to zero as the load increases. Measured results also show a whirl frequency ratio near 0.36 at no-load conditions; however, a zero whirl frequency ratio was obtained at all loaded conditions, indicating an inherently stable bearing from a rotordynamics viewpoint.
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September 2008
Research Papers
Static and Dynamic Characteristics for a Pressure-Dam Bearing
Bader Al-Jughaiman,
Bader Al-Jughaiman
Rotating Equipment Engineer
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Dara Childs
Dara Childs
The Leland T. Jordan Professor of Engineering
Search for other works by this author on:
Bader Al-Jughaiman
Rotating Equipment Engineer
Dara Childs
The Leland T. Jordan Professor of Engineering
J. Eng. Gas Turbines Power. Sep 2008, 130(5): 052501 (7 pages)
Published Online: June 5, 2008
Article history
Received:
October 22, 2007
Revised:
November 6, 2007
Published:
June 5, 2008
Citation
Al-Jughaiman, B., and Childs, D. (June 5, 2008). "Static and Dynamic Characteristics for a Pressure-Dam Bearing." ASME. J. Eng. Gas Turbines Power. September 2008; 130(5): 052501. https://doi.org/10.1115/1.2906173
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