Comparison Between Measured and Predicted Performance of a Two-Axial-Groove Journal Bearing

The results of a theoretical and experimental investigation of a two-axial-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 excitations, the linearized bearing coefficients are experimentally determined by an average magnitude and phase method. Numerical results are based on an algorithm which solves Reynolds equation for the circumferential pressure distribution with an assumed axial pressure profile. The model allows for a variety of thermal effects including circumferential and cross-film viscosity and temperature variation. Measured and predicted 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 numerical and experimental dynamic coefficients is very good, both in magnitude and in the slope of the coefficient vs. Sommerfeld number, with half of the coefficient predictions falling within the uncertainty bands of the measured data.