Computational models of bearings operating under extreme conditions for performance characteristics estimation

• Grant number: 23/11872-0
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2025
• End date: April 30, 2028
• Field of knowledge: Engineering - Mechanical Engineering - Mechanics of Solids
• Principal Investigator: Thales Freitas Peixoto
• Grantee: Thales Freitas Peixoto
• Host Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Since the Industrial Revolution (1760-1820), 2040 gigatonnes of carbon dioxide were emitted to the atmosphere, due to burning of fossil fuels, increasing in 1.09 °C the average global surface temperature above pre-industrial levels. Nearly 20% of the energy consumed worldwide is used to overcome friction and up to 40% of the lost energy can be saved employing new lubrication technologies. The lost energy due to viscous shear in mineral oils used as a lubricant separating two surfaces in contact still is the biggest cause limiting the efficiency of mechanical systems. In this scenario, rotating machineries with applications in different industrial segments represent a class of machines with broad applications, comprising turbines, compressors, pumps and generators. Particularly in the energy sector, performance is of paramount importance and losses due to friction should be minimized to guarantee an optimal performance. The need to satisfactorily predict the operating conditions requires an appropriate dynamic analysis, being required the proper knowledge of the influence of each component of the mechanical system, composed by the rotor, bearings, seals and supporting structures. The main difficulty in this type of analysis is the computational cost, often high, of a robust and complete analysis of the system components. This research project is included in a context of analysis and investigation of the dynamic behavior of rotating machineries, supported by hydrodynamic bearings, operating in extreme conditions (conditions of high rotating speed and low load or conditions of high load and low rotating speed). This project aims to develop robust models of lubricated bearings, investigating algorithms and holistic and efficient models, allowing for the complete analysis of the rotating system in a reduced computing time. Due to the extreme operating conditions, such models must consider the lubricant temperature variation, as well as other significant phenomena at high operating speeds, such as turbulence and thermal and elastic bearing deformation. The adequate flow prediction and lubricant loss in the bearings also require the use of mass conserving models to treat the inherent phenomenon of lubricant cavitation, that occurs in radial lubricated bearings. Finally, equipment malfunction due to bearing failures must be investigated, in order to assess the failure severity and its effect on the variables that can be monitored in the rotating system. Because of the operation in complex regimes, many rotating systems operate in non-linear regimes, requiring the study of the temporal response of the system, being necessary to integrate their equations of motion. The research project also proposes to investigate numerical integrators and to identify the most suitable and efficient integrator to perform the temporal integration of the equations of motion of a non-linear rotor supported by lubricated bearings. (AU)