Thermal analysis of fixed and tilting pad journal bearings including cross-film viscosity variations and deformations

This dissertation presents several enhancements to the thermal analysis of fixed geometry and tilting pad journal bearings. An approximate solution for a generalized Reynolds equation coupled with an approximate form of the energy equation is used to find the static and dynamic characteristics of several bearing geometries. The effect of including a cross-film viscosity variation in the solution is considered and found to be computationally expensive while generating changes greater than ten percent only for a few dynamic characteristics. Several models for the effect of cavitation on the cross-film heat conduction are studied and found to be helpful in determining the temperature field of the unloaded pads in fixed geometry bearings. Comparison with a published thermohydrodynamic solution indicate that this approximate analysis gives characteristic temperatures within ten degrees Fahrenheit, if boundary conditions are matched. Comparisons with two experimental investigations show correlation within eight degrees Fahrenheit of measured babbitt temperatures. Lack of agreement with measured eccentricities for a two axial groove bearing are attributed to modeling differences near the oil inlet.;The work with tilting pad bearings includes the cross-film viscosity variation and the thermal cavitation models. Neither of these effects is demonstrated to be important. Deformation models for the pivots and for the pads are outlined and investigated. The deformations, particularly the pivot deformations, are found to cause thirty percent changes in the operating eccentricity, with a lesser influence on the other characteristics. Neglecting the pivot stiffness in the reduction of the dynamic coefficients is shown to predict stiffness and damping values which can be a hundred percent higher than those reduced with pivot stiffness. An approximate pivot stiffness reduction introduces errors of about twenty percent for the three bearings considered. Comparison with the experimental work for these three bearings indicates that the iterative sump temperature model improves predictions of oil discharge temperatures for tilting pad bearings to within five degrees Fahrenheit. This boundary condition then improves the calculation of maximum babbitt temperature and of horsepower losses.