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Electro-mechanical magnetic blade pitch control

Periodic Reporting for period 1 - ROTATOR (Electro-mechanical magnetic blade pitch control)

Reporting period: 2020-06-01 to 2021-05-31

Open-rotor aero-engines offer an alternative configuration to conventional high-bypass gas turbine engines, They offer significant CO2
reductions, and for an industry producing over 600 million tonnes of CO2 yearly, adopting this engine could save 180 million
tonnes/year - a huge leap for the aviation industry and for the protection of our planet. Open rotor engines can also be configured to operate with future bio-fuels to remove fossil fuels entirely from flight.

The engine requires accurate control of the angle of the engine blades, and it is this area of control that
requires the greatest attention in order to realise the potential fuel savings. Current hydraulic systems transfer fluid to the
rotating actuator components in order to control the blade angle, requiring high-maintenance dynamic seals with potential for

The key areas of innovation in this project centre around the development of a fault tolerant electro-mechanical pitch control
mechanism utilizing an ultra-high torque density magnetically geared motor. The system is designed to be fault tolerant (it will remain in operation even after a number of systems failing) from
the rotating electrical power transfer device through to the mechanical actuator.

Innovative lightweighting technology will deliver a step-change in motor/actuator
weight-saving. A full-size actuator will be built and tested and a number of components and sub-assemblies of the actuator will be vibration
tested at representative temperatures. The coordinated research activities will take the technology from TRL2 to TRL4.
A specification has been developed through regular meetings with the Topic Manager and an IP landscape assessment has been completed with detailed searches returning a clear path to proceed.
A large number of concepts were considered, including mechanical actuation methods without a screw. The concepts have been studied in terms of their suitability to the application and detailed analysis, modelling and simulation tasks have been undertaken to determine whether the PCM system meets the specification in terms of mass, size, dynamic performance, fault tolerance etc. within the challenging operating environment.

Key component development areas for the PCM include fault tolerant electric drives, power transfer device, magnetically geared motor and development of lightweight mechanical actuation components. Research on the fault tolerant electrical drive uses silicon carbide technology to reduce losses and allow high operating temperatures. This work includes detailed switching models of the proposed drive. The fault tolerant, rotating, contactless power transfer system is under investigation using high frequency methods of electromagnetic power transfer where complex models and hardware have been developed and tested to understand the operation of the device.

Preliminary designs have been developed for the magnetically geared motor, including electromagnetic and thermal models and full simulation models of the PCM to define the motor specification through simulating real-world flight cycles. The fault tolerant magnetically geared motor was found to be 50% of the mass of an equivalent PM motor.

Analytical tools have been created for the design of the actuator in terms of predicting the component lifetimes and models to predict the behaviour of the components during operation have been created.

A key element of the ROTATOR project is lightweighting. Both metallic and composite parts have been the subject of research in order to provide a light but also reliable and safe mechanism. Novel manufacturing methods and concept part generation have been completed to a concept level, allowing a design to be down-selected that is within the specified maximum weight.
Current hydraulic pitch control systems transfer fluid to the rotating actuator components in order to control the blade angle, requiring high-maintenance with potential for leakages. This project seeks to entirely remove hydraulics from the PCM through the introduction of a magnetically geared drivetrain and non-contact rotating electrical power transfer. Research in to magnetically geared motors (PDDs) and comparison with various high torque density permanent magnet motors has shown that the PDD has a significantly higher torque density. This results in a lighter and smaller machine. Novel methods of construction of the PDD have been studied to enable a robust but lightweight design. Novel methods of providing mechanical fault tolerance in the case of a jammed nut/screw are the subject of ongoing research. Simulation models of the PCM system have allowed designs to be pushed harder in terms of torque density. Novel methods of construction for actuator components have been investigated, resulting in significant mass reduction over state-of-the-art methods. Lightweight, fault tolerant, high frequency SiC converters and rotating transformers are under investigation.

The project has recently completed the concept design stage. The current results show that the down-selected PCM is capable of meeting the onerous specification requirements. At this stage it is expected that the project will deliver a fully functioning PCM with associated project results arising from both the development of the digital twin and physical measurements on a full-sized demonstrater in 2023. The potential impact of the project remains unchanged. A fully electric PCM will help deliver the goals of the Open Rotor Engine which will transform the aircraft industry in terms of CO2 and NOx reduction. Specifically, it could save 180 million tonnes of CO2 per year - a huge leap for the aviation industry and for the protection of our planet. The project has also been designed to promote job creation and diversity within the Europeamn Union, foster new ideas and intellectual property and develop technologies that will have a wider impact outside the aerospace industry. This approach will promote the technology developed within ROTATOR in driving further reduction in CO2 in the aerospace, marine and automotive transport sectors, and also in renewable energy systems where magnetically geared machines offer the highest annual energy production
CAD rendered image of the Pitch Control Mechanism concept