Load Influence on Hydrostatic Oil Film Journal Bearing Stiffness Characteristics

Abstract

Hydrostatic bearings are widely used in industry, including aerospace and energy sectors. Hydrodynamic lubrication mechanism has been well studied analytically and experimentally and various types of bearings were developed to provide increasing operating speed, load capacity, stability and efficiency for modern rotating machines. Hydrostatically lubricated bearings have principal difference (in comparison with hydrodynamic bearings) and their characteristics have been an area of continued research. The goal of this work is to develop a robust algorithm, which can predict hydrodynamical characteristics and dynamic stiffness and damping coefficients of hybrid and hydrostatic bearings with increased accuracy and which can be used for engineering/design purposes. The developed approach is based on Reynold’s equations, where the unknown parameters are the rotor position and fluid pressure in recess pockets. Finite difference method in combination with the successive over-relaxation algorithm is used for a numerical solution of Reynold’s equations. Newton’s method is applied to solve the generated system of equations. Applying the developed approach, the effect of load influence on the hydrodynamical and the dynamic stiffness characteristics has been studied. Several hydrostatic bearing designs which are based on the published data were considered to compare the results calculated applying the approach with the experimental and theoretical data given in the literature. Performed study shows when journal eccentricity can’t be neglected while simulating hydrostatic bearing characteristics. Simulations also allow for analysis of how different design/geometrical parameters and initial conditions (supply pressure) influence bearing performance characteristics. The developed approach can be utilized as a practical tool which allows for the prediction of performance characteristics of hydrostatic bearing with increased accuracy.

Desenvolvimento do modelo numérico de uma bancada de rotor flexível suportada por um mancal sem contato baseado em filme de ar espremido

“…Estes mancais apresentam uma grande suavidade de movimento, boas características de amortecimento de vibrações, elevada rigidez do filme fluido, alta precisão de movimento, atrito inicial nulo e bom desempenho dinâmico (TSUKAMOTO, 2003). No entanto, as principais desvantagens dos mancais hidrostáticos são a complexidade e o custo relativamente alto do sistema de lubrificação, a necessidade de instalação de equipamentos auxiliares para a filtragem e o resfriamento do fluido lubrificante e o alto consumo de energia devido às perdas por bombeamento (MOROZ et al, 2020).…”