Numerical and experimental study of windage power loss in high-speed double helical gears considering the influence of oil-air volume ratio

The influence of windage power loss becomes significant when the gears rotating in air-oil mist with high velocities. The windage power loss is resulted from pressure drag and viscosity drag of the fluid in gearbox. Moreover, the viscosity drag is highly related with the oil-air volume ratio. Thus, to investigate the flow field and the influence of oil-air volume ratio on the windage power loss, a two-phase CFD model for the gearbox with oil-jet lubrication was developed. Simulation results of the windage power loss were obtained based on numerical method with varying oil-air volume ratio. It was found that the oil-air volume ratio and windage power loss increases with gear-rotating speed and oil-spraying flow-rate. Meanwhile, experimental results of the windage power loss considering oil-air volume ratio were obtained by the equivalent torque method, bearing friction torque model, and thermal elasto-hydrodynamic lubrication analysis. The experimental results are in good agreement with the numerical results. Furtherly, the windage power loss increase with oil-air volume ratio for the same gear-rotating speed. From the point of reducing windage power loss, it is necessary to consider the influence of oil-air volume ratio when designing the spraying parameters of oil-jet lubrication.