Abstract:

The traction coefficients of several aviation lubricating oils are measured at various operating conditions simulating an aviation engine bearing on a selfmade test rig. The predicted values of traction coefficients are calculated by various rheological models including the Newtonain model, Erying model, and Johnson Tevaarwerk model. The results show that aviation lubricating oils behave visco-elastic at small slide-to-roll ratios and behave viscous at large slide-to-roll ratios in the condition of elastohydrodynamic lubrication. The calculated results of the traction coefficients are significantly affected by the use of different rheological models. The lubricant traction coefficients in the elastohydrodynamic lubrication condition cannot be appropriately predicted by the Newtonian model. Through all the experimental conditions the predicted precision for lubricant traction coefficients is fairly high by the Johnson Tevaarwerk model, while this model has low precision for predicting the traction coefficients at the thermal effect region when the thermal effects in the contact zone are significant. Therefore, this rheological model needs to be improved in the future.

Key words: aviation, lubricating oil, bearing, traction coefficient, rheological model