Open rotor systems to be windtunnel tested by GE and NASA

With the refurbishment of a special NASA test rig, GE Aviation and NASA will begin a windtunnel test programme this summer to evaluate counter-rotating fan-blade systems for "open rotor" jet engine designs.

The testing will be conducted throughout 2009 and early 2010 at windtunnel facilities at NASA's Glenn Research Center in Cleveland, Ohio. GE and NASA stress that this is not a full engine test, but a component rig test to evaluate subscale fan systems
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In the 1980s, GE successfully ground-tested and flew an open-rotor jet engine that demonstrated fuel savings of more than 30% compared with similar-sized conventional, ducted front fan systems.

"The tests mark a new journey for GE and NASA in the world of open rotor technology," said David Joyce, president of GE Aviation. "These tests will help to tell us how confident we are in meeting the technical challenges of an open-rotor architecture. It's a journey driven by a need to sharply reduce fuel consumption in future aircraft."

GE and the Fundamental Aeronautics Program of NASA's Aeronautics Research Mission Directorate in Washington are jointly funding the programme. Snecma, GE's longtime 50/50 partner in CFM International, will participate with fan blade designs.

For the NASA tests, GE will run two rows of counterrotating fan blades, with 12 blades in the front row and 10 blades in the back row. The composite fan blades are 1/5 subscale in size. They will be tested in simulated flight conditions in Glenn's low-speed windtunnel  to simulate low-altitude aircraft speeds for acoustic evaluation, and also in Glenn's high-speed windtunnel to simulate high-altitude cruise conditions to evaluate blade efficiency and performance.

NASA's test rig, now refurbished and modernised, was used in the 1980s when NASA and GE first tested scale-model, counter-rotating fan systems that led to the development of the open rotor GE36 engine. Though enormous efficiency was demonstrated by this fan system, as fuel prices fell sharply in the late 1980s and early 1990s, the GE36 was never launched commercially, though it was recognised as a technology breakthrough.

In total, GE and NASA will run six different sets of blades in the NASA windtunnels, including five sets of modern blade designs. GE designed and fabricated the scale-model blades at its Cincinnati facility using technical input provided by the GE Corporate Research Center in New York.

Open-rotor designs are among the longer-term technologies being evaluated for LEAP-X, CFM technology programme focusing on future advances for next-generation CFM56 engines.