Torque Losses Induced by Oil-Jet Lubrication in a Rotating Gear: Experimental Measurements and VOF-Based CFD Analysis

Accurately characterizing the interaction between an oil jet and a rotating gear is essential for predicting load-independent losses in high-speed transmissions. CFD is increasingly employed to analyze oil-jet lubrication, yet the literature still provides only a limited amount of experimental data acquired under controlled conditions, leading to persistent uncertainties regarding the full predictive maturity of available numerical approaches. This study investigates the jet-gear interaction through a dedicated experimental setup specifically designed to measure the torque generated by an impinging oil jet on a spur gear. Measurements were conducted over multiple operating conditions using a differential procedure that isolates the net effect of the jet from other mechanical contributions. In parallel, a detailed three-dimensional CFD model was developed in SimericsMP+, incorporating a refined multiphase representation of the jet and a moving-grid treatment of gear rotation. A separate model of the injection nozzle was used to determine the effective jet velocity corresponding to the measured flow rates. The combined experimental and numerical analysis enables assessing the capability of the solver to reproduce the resisting torque as a function of flow rate and rotational speed. The comparison between simulations and measurements shows consistent agreement across the investigated range, confirming the reliability of the proposed modelling strategy for analyzing jet lubrication phenomena. The validated methodology provides a transferable basis for future studies involving entire gear trains and more complex lubrication configurations.