Initial results investigating windage power loss on a rotating shrouded spiral bevel gear using a parametric solid model and Computational Fluid Dynamics (CFD) are presented. The context behind this study is a desire to use CFD as a tool to investigate heat-to-oil within gas turbine bearing chambers and gearboxes in order to reduce costly rig-based experiments. This paper contains the methodology for creation of the parametric model of a spiral bevel gear in Pro/Engineer, formulation of a mesh in ICEM CFD and the subsequent CFD analysis in Fluent 6.2.26 and 12.0.16. A single tooth segment of a 91 teethed spiral bevel gear is produced with periodic boundaries imposed to reduce computational cost. Validation against experimental results for a single control gear is shown with particularly good correlation between static pressure rise across the face of the gear. Mesh verification is also presented. Using the model to change the module of the gear (effectively the number of teeth), investigations show that windage power loss reduces when the number of teeth increases. Analysis of the static pressure variation throughout the domain shows that all gears tested exhibit a linearly increasing relationship between non-dimensional mass-flow-rate and the pressure drop through the shroud restriction. The control gear was seen to have only a weak increase in static pressure gain across the gear tooth as the mass-flow-rate increases; however, a far larger increase exists for the module cases tested — at comparable mass-flow-rates to the control gear. As the number of teeth increase, the pressure gain across the gear reduces, and vice-versa. It is this difference between the gears that results in dissimilar windage power losses.

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