Computational Fluid Dynamics Applied to Lubricated Mechanical Components: Review of the Approaches to Simulate Gears, Bearings, and Pumps

Lorenzo Maccioni,Franco Concli

doi:10.3390/app10248810

Lorenzo Maccioni, Franco Concli

Open Access

https://doi.org/10.3390/app10248810

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Journal: Applied Sciences	Publication Date: Dec 9, 2020
Citations: 30	License type: CC BY 4.0

Affiliation: Free University of Bozen-Bolzano

Abstract

The lubrication of the mechanical components reduces friction, and increases the efficiency and the reliability. However, the interaction of moving components with the lubricant leads to power losses due to viscous and inertial effects. Nowadays, the study of lubricant behavior can be carried out through computational fluid dynamics (CFD) simulations. Nevertheless, the modeling of the computational domain within complex mechanical systems (e.g., ordinary, planetary and cycloidal gearboxes, roller bearings, and pumps) requires the exploitation of specific CFD techniques. In the last decades, many mesh-based or meshless approaches have been developed to deal with the complex management of the topological changes of the computational domain or the modeling of complex kinematics. This paper aims to collect and to classify the scientific literature where these approaches have been exploited for the study of lubricated mechanical systems. The goal of this research is to shed a light on the current state of the art in performing CFD analysis of these systems. Moreover, the objective of this study is to stress the limits and the capabilities of the main CFD techniques applied in this field of research. Results show the main differences in terms of accuracy achievable and the level of complexity that can be managed with the different CFD approaches.

Highlights

The lubrication of mechanical components plays a key role in ensuring their reliable functioning in terms of wear reduction, efficiency improvement, and in maintaining an appropriate operating temperature both by reducing the heat generation and by promoting its dissipation [1]
A bibliographic search has been performed in order to acquire a deeper knowledge of the state of the art concerning the capability of the available computational fluid dynamics (CFD) approaches to model the fluids behavior in complex geometries, kinematics and/or by simulating specific physical phenomena
The most pertinent paper in which a CFD approach have been exploited to study the lubrication in specific mechanical components/systems were collected and classified

Summary

Introduction

The lubrication of mechanical components plays a key role in ensuring their reliable functioning in terms of wear reduction, efficiency improvement, and in maintaining an appropriate operating temperature both by reducing the heat generation and by promoting its dissipation [1]. Even if the lubrication allows the reduction of power losses due to friction, the interaction between the lubricant and the moving structures implies additional power losses due to viscous and inertial effects [2] The prediction of these power losses has been studied in the past through experimental tests. Based on these measurements, several empirical/analytical models have been proposed [3]. Several empirical/analytical models have been proposed [3] Those models are unreliable for predicting power losses when the geometries, the speeds or the lubricant properties differ from those observed/selected during the experimental tests [3]. The averaged generic field property (φ) of the mixture in each cell of the domain can be calculated as an α-averaged value of the properties of the different fluids/phases, e.g., air and lubricant (Equation (4))

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