Light Weight and Low-Misalignment Planetary Gear System for Open Rotor Power Gearbox

Abstract

The future aero engines expected to have the best fuel efficiency are those with the open rotor propulsion system. It has two rows of propellers rotating in opposite directions. The rotational speeds of the propellers are reduced by a power gearbox. The power gearbox is designed as a differential planetary gear system with double helical teeth. The gearbox for aero engines needs to be lightweight and highly reliable. Misalignment on the gear pair affects adversely the reliability of the gears. The misalignment analysis of the power gearbox based on finite element analysis was carried out. The inclination of the planet spindles associated with the twisting deformation of the planet carrier was identified as the major cause of the misalignment. We developed an innovative design method to achieve the low misalignment and lightweight at the same time by optimizing the stiffness balance of the planet carrier. The optimization analysis was carried out extensively in the design work. The planet carrier design was named Analysis Configured Engineering planet Carrier (ACE CARRIER). A stress measurement was planned to validate the design concept of the ACE CARRIER. A test gearbox was manufactured.

Preliminary Design Framework for the Power Gearbox in a Contra-Rotating Open Rotor

“…Kawasaki Heavy Industries (KHI) investigated a geared CROR engine and the design of its transmission system with a prototype of a DPGB developed to demonstrate a technology readiness level (TRL) appropriate for whole engine development [28]- [30].…”