A 3-D Computational Fluid Dynamics Modeling of the Churning Loss and Oil Pattern in a Single-Stage Gearbox

Modern gearboxes are meticulously engineered with three primary objectives: enhancing load-carrying capacity, minimizing noise, vibration, and harshness (NVH), and optimizing efficiency. Efficiency, in particular, holds paramount significance due to gearboxes’ substantial influence on energy consumption. One effective strategy for boosting efficiency involves curbing churning losses, stemming from the movement of oil within the gearbox housing. Computational fluid dynamics (CFD) techniques have emerged as invaluable tools for visualizing oil flow dynamics within gearboxes and pinpointing avenues for mitigating churning losses. In the context of electric vehicles (EVs), specifically battery electric vehicles (BEVs), extending their driving range is a top priority. Achieving this hinges on the design of an efficient gearbox. This study employs an oil/air multi-phase volume of fluid (VOF) method in a commercial CFD solver known as Simerics-MP+ to model the oil flow and churning losses within a single-stage gearbox. The model’s predictions are validated against previously published highspeed camera footage and measurements derived from the FZG noload power loss test rig’s single-stage gearbox. The simulation results underscore the potential of CFD simulations in providing an exceptionally detailed portrayal of oil flow behavior, while also aligning closely with experimental measurements concerning churning losses. Additionally, two different modeling approaches for gearbox simulations are compared and the advantages are discussed. This study provides engineers with a new tool that can be used to improve the efficiency and reliability of gearboxes in BEVs.