Advanced propeller bearings for open rotors
An aircraft propeller is a heavy device consisting of a rotating hub with radiating blades that produces thrust by pushing air. One of the latest designs under development within the EU's ambitious Clean Sky research programme is the Sustainable and Green Engine (SAGE) demonstrator SAGE 2, sporting two propellers in an open rotor concept. Spinning in open air, the open rotor could significantly increase air flow and thrust, thus reducing fuel consumption and emissions. The blade bearings play a critical role in load management and blade angle control. Scientists working on the project 'NTN-SNR proposal for propellers blades bearings design and manufacturing' (SNRPBBEARING) are developing innovative demonstrators to support the effort. During the first project period, researchers evaluated various bearing architectures for the ability to meet specifications. Two designs were then subjected to finite element calculations to evaluate the effects of the stiffness of parts in contact with the bearings. One concept is now being pursed. The team has developed an advanced tribological system to be located inside the bearing to withstand the large loads and high temperatures. In addition, innovative sealants are under evaluation to both keep lubricants in and pollutants out. Following a successful preliminary design review, the team is now working on design improvement according to comments from the manufacturing process review and relevant integration issues. Researchers are also finalising a detailed definition of the tribological system. In the end, SNRPBBEARING plans to deliver 26 bearings for the SAGE 2 propellers at a technology readiness level of 5, meaning thorough testing of the prototype in a representative environment. The bearings will thus be ready for testing in a relevant full-scale realistic scenario partially integrated with other systems. When SAGE 2 takes flight, project bearings are likely to be supporting the innovative open rotor for reduced fuel consumption and emissions.
Keywords
Propeller, bearings, open rotors, blades, tribological systems