Minimizing Heat Rejection in Aircraft Accessory Drive Gearboxes

A test program was initiated to study the effects of improved lubrication delivery on the total heat rejection of an aircraft accessory drive gearbox. The goal of this program was to reduce the overall gearbox heat rejection by minimizing the viscous drag and churning losses.

The most practical heat sink available to secondary power subsystems on supersonic aircraft is the fuel supply; and due to its limited capacity, reduced heat rejection from these systems is very desirable.

A model of gearbox cooling requirements will be presented and compared with the lube distribution of a baseline gearbox and subsequent modified configurations. The effects of oil-in temperature, and lube gallery pressure on heat rejection are shown, with emphasis placed on minimizing this heat rejection.