A Multi Domain Modeling Approach for the CFD Simulation of Multi-Stage Gearboxes

Marco Nicola Mastrone,Franco Concli

doi:10.3390/en15030837

Marco Nicola Mastrone, Franco Concli

Open Access

https://doi.org/10.3390/en15030837

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Journal: Energies	Publication Date: Jan 24, 2022
Citations: 9	License type: CC BY 4.0

Affiliation: Free University of Bozen-Bolzano

Abstract

The application of Computer-Aided Engineering (CAE) tools in mechanical design has consistently increased over the last decades. The benefits introduced by virtual models in terms of time and cost reductions are the main drivers for their exploitation in industry as well as for research purposes in academia. In this regard, Computational Fluid Dynamics (CFD) can be exploited to study lubrication and efficiency of gears. However, the mesh handling complexities deriving from the boundary motion is still a concern for its application to multi-stage gearboxes. In this work, an innovative multi domain partitioning method for the simulation of a two-stage industrial speed reducer is presented. The implemented solution foresees the combination of two remeshing strategies, namely GRA (Global Remeshing Approach) and GRAMC (GRA with Mesh Clustering), and resulted in a computationally effective performance. The results were compared with experimental data obtained with measurements on the real system, providing a good agreement in the power losses prediction. Considering the complexity of obtaining such results experimentally, the proposed numerical algorithm can offer substantial benefits for an estimation of the transmissions’ efficiency in various operating conditions. The numerical model was built in the open-source environment OpenFOAM®.

Highlights

The reduction of wear in mechanical components as well as the more stringent requirements in terms of energy savings require the proper design of mechanical transmissions to ensure a proper lubrication supply
Windage refers to the losses that arise from the interaction of mechanical components and one fluid only
In order to isolate the gears’ losses (PLG), the power losses include the bearing (PLB) and the PLD contributions have been calculated according to the ISO 14179 [47] and subtracted from the total losses

Summary

Introduction

The reduction of wear in mechanical components as well as the more stringent requirements in terms of energy savings require the proper design of mechanical transmissions (i.e., gearboxes) to ensure a proper lubrication supply. The lubricant is a fundamental design factor to guarantee a long functioning time and to reduce the downtime periods of the system. Due to the mutual interaction between the lubricant and the system’s components, additional power losses originate. These losses are called load-independent (or no-load) and can be subdivided in three main contributions: churning, squeezing and windage. The churning phenomenon is typical of dip lubrication conditions, where the oil resistance to the mechanical components’ movement causes high pressure and viscous effects. Windage refers to the losses that arise from the interaction of mechanical components and one fluid only (e.g., gears completely immersed in oil). The pressure gradients in the engagement region generate axial fluxes that promote the squeezing power losses ( called pocketing)

Results

Discussion

Conclusion