A Windage Power Loss Model for Spur Gear Pairs

Abstract

This article proposes a simplified fluid mechanics–based model to predict the windage power loss of a spur gear pair operating under jet lubrication conditions. In this model, the total windage power loss is defined as the sum of (a) the losses associated with the interactions of individual gears with the air or air–oil mixture and (b) the losses due to pocketing/squeezing of the same medium at the gear mesh interface. The first group of losses is modeled through a formulation for air drag forces induced on each rotating gear body along its faces and periphery (circumference). The pocketing power loss is modeled analytically through a compressible fluid flow formulation. The windage power loss model predictions are compared to published gear pair windage experiments and empirical formulae to assess their accuracy. Results of a parametric study are also presented to quantify the impact of key system parameters as well as individual contributions of each component to the total windage power loss.