Comparison of computational models to evaluate the impact of cavitation on the static performance of lubricated bearings

• Grant number: 24/00436-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2024
• End date: March 31, 2026
• Field of knowledge: Engineering - Mechanical Engineering - Mechanics of Solids
• Principal Investigator: Thales Freitas Peixoto
• Grantee: Natália Aparecida Ferreira
• Host Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Hydrodynamic bearings are used to support rotating machines, because they allow operation at high rotational speeds. Its working principle is based on the idea of separating the rotating shaft from the bearing stationary surface with a lubricant, allowing operation under infinite life, since no metal-metal contact between the shaft and the bearing occurs and, therefore, bearing wear is prevented. The lubricant capacity to sustain the load is due to the formation of a converging wedge that increases the lubricant pressure, generating hydrodynamic forces that sustain the rotating shaft. The mathematical model that describes this pressure increase is given by the Reynolds equation, whose solution provides the lubricant pressure distribution along the bearing. However, in cylindrical bearings, there is a divergent wedge, responsible to reduce the lubricant pressure, which decreases to the ambient pressure value, releasing the dissolved gases in the lubricant. This phenomenon is called cavitation. Several cavitation models have been proposed in the literature, in order to adequately predict the pressure distribution experimentally observed in hydrodynamic bearings. This scientific initiation aims to study and compare different cavitation models found in the literature, in order to investigate the effect of mass conservation on the cavitation model in the bearing static performance characteristics. It should be emphasized that the several models proposed in the literature present different equations, solution algorithms and regularization strategies, in order avoid the numerical problems found in the classic Elrod model, to solve the dual problem of find the pressure distribution and cavitation region in the bearing. So, this work aims to identify the better algorithm in terms of computational performance and the impact of each model in estimating the static performance characteristics of the cylindrical bearing.