Rolls Royce : Electrical team readies for its biggest power...

Electrical team readies for its biggest power challenge

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Power Generation System readies for its first run, with big challenges and big aspirations ahead.

An artist's impression of the TP108 tested in Bristol

In an unassuming, newly-converted testbed, tucked away on the Rolls-Royce site in Bristol, UK, a team is getting ready to do battle with the laws of physics.

For it is here that Power Generation System 1 (PGS1) - the most powerful hybrid-electric engine in aerospace - is being brought together for its first ground test run in 2021.

And this will be no ordinary engine first run, for it will be the first try out of a hybrid-electric system that has extraordinary goals if it is to power future aircraft at MW scale.

At its heart is a generator - no bigger than a beer keg - that has to deliver 2.5MW, enough electrical power to supply 2,500 homes. And, in an aerospace industry with strict standards, it has to do that safely and reliably.

All the cables are in place, ready to connect up the components of PGS1, linking the generator to an AE2100 gas turbine and a 3000V power electronics system. And that connection will take place soon, once the final stages of generator trials have concluded at another bespoke high voltage Rolls-Royce test facility in Trondheim, Norway.

Riona Armesmith, Chief Project Engineer, Hybrid Electric Propulsion, is leading the Bristol team's quest and recognises the scale of the challenge.

She said: 'The majority of engineering testing is carried out to prove something that has already been largely validated on another vehicle or through computer simulation. But this is testing at the limits - to actually see if we can make PGS1 work and to generate data which will allow us to validate our models for the first time.

'The challenge of this type of hybrid technology at this level of power is really about weight and thermal management. Batteries weigh more than kerosene and once you have added on cables, power electronics and the cooling systems for each component you also have unavoidable increased complexity.

'So we have to make PGS1 as light, reliable and simple to operate as possible. And if we achieve that we will be in a great position, with a fully-integrated and ground-tested power and thermal management system. It means whenever anyone comes forward with a hybrid or all-electric aircraft concept requiring MW power, we will be ready to go.'

PGS1 has risen from a demonstrator programme that was part of the E-Fan X programme being developed with Airbus, which concluded earlier this year when both parties recognised there was no requirement to create an actual aircraft for test flight.

But Rolls-Royce is continuing with PGS1 testing, ensuring it can be integrated into any future aircraft that requires a hybrid-electric propulsion system at MW scale, which could then be flight-tested to confirm that all industry safety requirements are met.

'Like every other business, we've had to adapt to the impact of COVID-19 which has slowed our work down, and also coming out of E-Fan X meant we reconfigured the programme to our own needs,' adds Riona.

'But we are now gearing up for what promises to be a very exciting 2021 and we are hoping for a series of successes, starting with the run to full power in Trondheim, which complements our work in Derby to prove our hybrid-electric engine control systems, and in Indianapolis on our thermal management system.'

PGS1 fits into a Rolls-Royce electrification programme, which in turn is part of a wider sustainability strategy designed to enable the sectors in which we operate achieve net zero carbon by 2050.

Developing PGS1 will give us a greater understanding of delivering electrification in the MW category. We are also actively involved in a range of aircraft programmes that are in the KW-class.

Electrification makes up one element of our research into new propulsion technologies, which also includes the use of hydrogen, with both technologies closely related. And while that research continues to mature, we are also focusing on two other key elements in our sustainability strategy: continuing to improve gas turbine efficiency and promoting the increased use of sustainable aviation fuels.

Riona adds: 'The environment was already an important issue for aviation pre-COVID 19 and I believe that once we have recovered from the shock it has brought all of us, we will want to connect again and see each other again - but doing that sustainability will be even more important.

'That is why this work, while a huge technical challenge, is also a great motivation. Because electric systems like ours can play a part in decarbonising aviation - it is one of the most fundamental questions society asks of us, and it is exciting to be just one part of the solution.'

• Part of the new technology development for the hybrid-electric test bed, known as TP108, and for PGS1 has been supported by the Aerospace Technology Institute's MegaFlight project.

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