Experimental and Predicted Rigid Rotor Stability Threshold of Axial Groove and Three-Lobe Bearings

• Published in: International Journal of Rotating Machinery 2002, Vol.2002 (1), p.27-33
• Main Authors: Flack, R. D., Kostrzewsky, G. J., Barrett, L. E.
• Format: Article
• Language: English
• ISSN: 1023-621X; 1542-3034; 1563-5090
• DOI: 10.1155/S1023621X02000039

The measured performances of axial groove and preloaded three-lobe journal bearings are compared with the predicted performance. Operating eccentricity and dynamic coefficients were found for different shaft speeds and various steady loads. Numerical results are based on a Reynolds equation solver, which allows for a variety of thermal effects. Sinusoidal excitations were used to experimentally determine the eight linearized stiffness and damping coefficients. The rigid rotor stability threshold parameter, ω_s, and whirl ratio, ω_d, were found from the dynamic coefficients. The experimental and theoretical stability threshold and whirl ratio are correlated as independent functions of both the Sommerfeld number and operating eccentricity. The predicted stability maps are slightly higher than measured, indicating that the predicted characteristics are more stable than measured. The predicted whirl ratios are in approximate agreement with measured values. As expected, the stability maps show the axial groove bearings to be less stable than the preloaded three-lobe bearings.