NASA and General Electric are negotiating a new partnership agreement to start scaled model tests of open-rotor counter-rotating fan systems later this year for a next-generation jet engine design for the narrowbody sector.
Tests would use windtunnels at NASA's Glenn Research Center, and NASA would also supply testing rig equipment originally used in the 1980s for fan systems that led to the GE36 jet engine programme.
The GE36, which featured an unducted fan installed on the aft fuselage Boeing 727 and Boeing MD-80, was also jointly funded by NASA and GE, but was cancelled despite a successful flight-test programme showing the possibility of a 30% fuel efficiency improvement over conventional engine fans.
Now, the potential fuel savings promised by the ultra-high-bypass open rotor design could drive the performance requirement for a new class of aircraft that will replace the MD-80, 737 and Airbus A320 fleets over the next 30 years.
But many questions remain about the technical viability of the open-rotor concept. GE must prove that the engine can satisfy a number of technical and regulatory barriers, such as meeting blade-out, reliability and installation standards, and it is working to prove the validity of the counter-rotating fan for the open rotor design.
Meanwhile, CFM International, the GE-Snecma joint venture, is considering the open-rotor concept to replace the CFM56 turbofan after 2017.
CFM is developing technologies for the core of a next-generation engine called Leap56. The same technologies could also be applied to power the counter-rotating blades for a next-generation engine design.
Source: Flight International
