Churning power losses of ordinary gears: a new approach based on the internal fluid dynamics simulations

Abstract

The increasing need of more and more efficient gearboxes implies the need of predictive models in order to compare, during the design stage, different design solutions. The models provided by literature are mostly experimentally derived and not accurate on real applications. A new trend suggests the adoption of computational fluid dynamics (CFD) for the calculation of the no-load losses of gear transmissions. In this sense, literature provides some works, but most of them involve only one single phase. In this paper, the real operating condition in which the gears are immersed in an oil lubricant mixture is studied. Adopting an opensource code, OpenFOAM®, the influence of some operating and geometrical parameters on the churning losses has been investigated. The aims are both to provide data that can be effectively used by engineers in the design practice and to prove, once again, CFD to be an effective approach for this kind of investigations.

Effect of the static pressure on the power dissipation of gearboxes

“…The reduction of the power loss can be explained looking at the way in which, with the lower static pressure, the air pillow (Figure ) that takes place around the submerged portion of the gear completely covers the teeth while for the environment pressure condition, air is trapped only in the bottom of the teeth gaps and the teeth tips interact with the lubricant (higher viscosity and density and consequent pressure peaks) causing the higher power dissipation. In dip‐lubrication, in fact, the loss is significantly dependent from the distribution of the contact areas between teeth and the lubricant …”

“…In dip-lubrication, in fact, the loss is significantly dependent from the distribution of the contact areas between teeth and the lubricant. 28…”

Numerical modeling of the churning power losses in planetary gearboxes: An innovative partitioning‐based meshing methodology for the application of a computational effort reduction strategy to complex gearbox configurations

“…Recently, different authors among which Marchesse et al, Hill et al, and Gorla et al applied computational fluid dynamic (CFD) for such purposes. The results of different researches have shown the effectiveness of the CFD approach for the characterization and the optimization of the power losses of gears . The CFD allows to model each specific operating conditions and design overcoming the main limitation of the empirical models.…”

A New Integrated Approach for the Prediction of the Load Independent Power Losses of Gears: Development of a Mesh-Handling Algorithm to Reduce the CFD Simulation Time

“…The main limitation to the wide diffusion of such approaches is related to the computational effort, the complexity of setting up a model with a general-purpose software, and the costs for the licenses. In this scenario the authors started studying a simplified configuration [23,24] with the opensource code OpenFOAM [25]. This approach allows both to overcome the license costs (GNU license) but also, thanks to the specificity of the developed algorithm, to reduce the setup and calculation times.…”