COMPARISON BETWEEN MEASURED AND PREDICTED PERFORMANCE OF A 2-AXIAL-GROOVE JOURNAL BEARING

The results of a theoretical and experimental investigation of a two-a xial-groove journal bearing are presented. Operating eccentricity and dynamic coefficients vs. Sommerfeld number are compared for two shaft speeds and various steady loads. Using synchronous, sinusoidal excitat ions, the linearized bearing coefficients are experimentally determine d by an average magnitude and phase method. Numerical results are base d on an algorithm which solves Reynolds equation for the circumferenti al pressure distribution with an assumed axial pressure profile. The m odel allows for a variety of thermal effects including circumferential and cross-film viscosity and temperature variation. Measured and pred icted steady operating eccentricities are found to agree within three percent typically and 13 percent worst case. Predicted attitude angles are typically 9.5 degrees higher than measured. Agreement between num erical and experimental dynamic coefficients is very good, both in mag nitude and in the slope of the coefficient vs. Sommerfeld number, with half of the coefficient predictions falling within the uncertainty ba nds of the measured data.