European research to focus on open-rotor aircraft engines

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A Rolls-Royce-led research programme to investigate open-rotor engines and new fuels could be approved next month for a 2008 start under the European Commission's new Seventh Framework Programme.

The three-year Validation of Radical Engine Architecture Systems (Dream) programme will have a budget of at least €40 million ($55 million). The project is aimed at reducing fuel consumption and CO2 emissions while meeting acceptable noise levels.

Dream is focused on developing technology for contra-rotating open rotors with variable-pitch blades. These promise a 10-15% reduction in fuel burn, but are noisier than high-bypass turbofans. The team believes recent aero-acoustic design progress allows this engine architecture to be reconsidered for short/medium-haul airliners.

"Open rotors could replace today's turbofans," says Serge Eury, research and technology vice-president at Dream partner company Snecma. "Open rotors theoretically are more efficient, but some kinds could be very noisy. We need to check if we can produce an engine with no noise penalty, by examining blade design."

Eury expects new engine architectures including open rotors to be considered by the major airframe manufacturers for the next-generation single-aisle aircraft expected to enter production by the middle of the next decade.

snecma open rotor

R-R will lead work on a geared open-rotor engine that offers significant fuel savings and allows greater control of tip speed for noise control while using more conventional turbine technology. R-R's US arm was involved in NASA work on geared propfans in the 1980s.

Snecma will lead work on a direct-drive open-rotor engine, which offers significant fuel burn and CO2 reductions, but faces a challenge meeting noise levels lower than current Stage 4 limits. Snecma worked with General Electric on its GE36 unducted fan in the 1980s.

Led by Turbomeca, new fuels work under Dream will use a helicopter turboshaft and include studies of synthetic kerosene produced using the Fischer-Tropsch process as well as biofuel candidates with characteristics suitable for use in aircraft.