Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
STUDIES ON THE INFLUENCE OF CAVITATION BOUNDARY CONDITION MODEL ON THE PERFORMANCE OF TEXTURED SURFACE HYDRODYNAMIC JOURNAL BEARINGS
Submission Author:
Luiz Fellipe Nogueirão , SP , Brazil
Co-Authors:
Luiz Fellipe Nogueirão, Flávio Yukio Watanabe
Presenter: Luiz Fellipe Nogueirão
doi://10.26678/ABCM.COBEM2021.COB2021-0449
Abstract
The application of texturized surfaces can be found in many situations that found through its use a way of improving specific characteristics of the product and/or process. When the topic on discussion are hydrodynamic journal bearings, a simple way to understand the involved tribological parameters is by analyzing the standard Reynold’s equation. The equation states that the generation and distribution of the hydrodynamic pressure is affected by the geometries which limit the oil film formation, viscosity and density of the lubricant, and velocities. An up-to-date literature review is made for identifying the recommended static analysis methods for texturized hydrodynamic journal bearings. A comparison of the boundary condition types is elaborated for a cylindrical plain (not texturized) hydrodynamic journal bearing. This comparison meets the historical progress of the boundary conditions, which firstly did not include the influence of cavitation (Half-Sommerfedl/Gümbel boundary condition); progressing to models that did consider the cavitation influence, but since a mass conservation was still not respected, the results would show an excessive gain in load capacity (Reynold’s/Swift-Stieber boundary condition); resulting at last on a mass conservation condition that does include the cavitation effects (Jakobsson Floberg Olsson - JFO boundary condition). The present study evaluates the influence of textured surfaces through a model that is discretized by the finite difference method and considering a modified Reynold’s equation which includes the effects of cavitation and respects the mass conservation. The textures are considered as spherical grooves distributed on a specific pattern along the surface of the hydrodynamic cylindrical journal bearing. The results of the static analysis are compared with other studies for validating the model. The size, number and position of the inserted textures are varied to identify the best condition which produces highest load capacity and lowest frictional torque. The final best rated results of textured surfaces are compared with the non-texturized journal bearings and the gain is evaluated.
Keywords
Tribology, Surface Engineering, mass-conserving cavitation model, Finite Difference Method, spherical grooves
