Andrew Doyle/MUNICH

Rolls-Royce is to introduce new compressor blade technology in two members of the Trent engine family, which it hopes will yield a significant reduction in fuel consumption.

The blades - designed using three-dimensional aerodynamic (3-D aero) analysis software - will initially be used on the Trent 500 for the Airbus A340-500/600, and later on the Trent 8104 for growth versions of the Boeing 777.

"You're talking about a specific fuel consumption reduction of up to 2%, so it's big numbers," says Trent 800 chief engineer Paul Craig.

The technique has been used to design the intermediate pressure compressors (IPC) and high pressure compressors (HPC) in the two, three-shaft Trent models, and allows engineers to precisely optimise the "bow and sweep" of the blades to improve compressive efficiency.

"We are trying to design the blades to match what the air wants to do in all three dimensions," says Craig.

Following the initial development work performed by the Trent 800 development team, the technology was made available to BMW Rolls-Royce which, as a risk-sharing partner in the Trent 500 programme, is the design authority for the latter engine's HPC.

Craig says R-R is satisfied that the new blades will perform reliably on production Trent 500s, although the company has also designed a compressor with conventional blades as a back-up.

"We've done a lot of de-risking of the technology," says Craig. "We have run three Trent 800s with 3-D aero compressors and it's all worked very well. We view this as a low-risk technology," he adds.

The new blades will have to be tested extensively to meet extended-range twin-engine operations (ETOPS) requirements for the Trent 8104, although the ultra-long range 777-X twinjet programme has yet to be launched.

Initial components for the Trent 500 are in production and the first engine run is planned for May. Six development engines will have been completed by the end of 1999, with flight testing due to start on anA340-300 in January 2000. CFM International was one of the first manufacturers to introduce 3-D aero technology - for parts of some versions of the CFM56 - but advances in computing power allow it to be used for major sections of big-fan engines.

Fokker Elmo is the latest company to become a risk-sharing partner in the Trent 500, taking just under a 1% stake. The Dutch company will manufacture the electrical harnesses for the engine. One quarter of the Trent 500 programme has been placed with outside partners.

Source: Flight International