The XWB-97 that will airborne on Airbus’s A380 flying testbed around mid-2015, is a milestone engine in its own right. Derived from the 84,000-lb.-thrust Trent XWB-84 now powering the A350-900, the XWB-97 is rated at 97,000 lb. yet is externally identical to its lower-thrust sibling.
The engine is designed to power the 679,000-lb. maximum-takeoff-weight aircraft on ranges of up to
8,400 nm 8,000 nm (A350-1000 variant). Not only must this be achieved with the same efficiency of the baseline engine, it must be accomplished with the same 118-in.-dia. fan and external nacelle packaging.
Upcoming tests will focus initially on the newer design aspects of the XWB-97, specifically the higher-flow fan that pumps more air through changes to the tips and root areas of the blades.
The XWB-97 also is designed with a 5% larger core, higher-temperature capability and unshrouded high-pressure turbine blades. “The fan is turning 6% faster and is configured with an inflected annulus at the root, with detailed aerodynamic tweaks at the tip,” says Trent XWB Program Director Simon Burr.
“We have run the fan at higher speeds and already demonstrated well in excess of 100,000-lb. thrust on the XWB-84, so we have confidence in that,” he adds. The design also includes additional stages of blisks, 3 of which are used in the high-pressure compressor.
Burr also highlights the switch from a shrouded high-pressure turbine to an unshrouded design in the XWB-97. The technology is derived from the core of the EJ200 military engine used in the Eurofighter Typhoon and represents the first application of this design in a Rolls commercial engine.
“It enables us to do more work on that stage, and mechanically the system is scaled for more thrust,” he adds. However, the shroudless turbine, as with all major design trades, comes with complexities associated with the clearance control and cooling air systems.
As a result, Rolls has focused its early test efforts on the feature and is currently conducting trials on a set of full-scale shroudless blades in an XWB-84 demonstrator in the run up to XWB-97 tests.
Based on the article “Stepping Up” published in Aviation Week