Research on starvation evolution and temperature field prediction for spur gear under oil jet lubrication

Under extreme operating conditions, such as high-speed aerodynamic drag and restricted oil supply, jet-lubricated gears are highly prone to oil starvation. This phenomenon causes a rapid increase in contact zone temperatures, posing a significant risk of severe operational failure. Given that current research struggles to quantitatively characterize the global coupling mechanism between high-speed flow field evolution, starvation severity, and contact thermal response, this paper proposes a comprehensive thermo-hydro-mechanical coupled analytical framework encompassing the ‘oil supply conditions–starvation state–contact temperature’ chain. The study first utilizes Computational Fluid Dynamics (CFD) simulations to establish an analytical mapping model between jet parameters and the initial oil film thickness, enabling the precise quantification of starvation degrees. Subsequently, by integrating the Extended Tooth Contact (ETC) effect with Thermal Elastohydrodynamic Lubrication (TEHL) theory, a refined three-dimensional discretized thermal network model for the tooth surface is constructed. Numerical results indicate that high-speed-induced attenuation in oil supply leads to significant film thinning and a surge in friction, which exacerbates the bulk temperature rise. Furthermore, the secondary contact induced by the ETC effect generates sharp transient thermal gradients at the meshing boundaries, triggering extreme flash temperature spikes. Infrared thermography experiments confirm that the model's predictions for bulk temperature are in high agreement with measured results. Compared to the classical Blok's theory, the proposed method more accurately captures extreme temperature rise characteristics at the meshing boundaries. This work provides valuable theoretical insights for high-reliability design, anti-scuffing assessment, and the optimization of lubrication and cooling systems for power transmissions operating under extreme conditions.