GE Aviation and NASA are to ground test five sets of new subscale blades for open-rotor engines at NASA’s Glenn Research Center in Cleveland, Ohio. The tests will focus on acoustics and efficiency of a two-stage counter-rotating fan. The two partners have high expectations that new analysis tools will add to their understanding of the fan’s aerodynamics.

Testing will start this summer and last until early 2010. With 12 blades on the front row and 10 blades on the second row, the one-fifth scale system will be tested in two wind tunnels. The low-speed wind tunnel will simulate flight at low altitude and will help acoustic evaluation. The high-speed wind tunnel will rather simulate high-altitude cruise conditions. Blade efficiency and performance will be tested there.

Before running the five sets of new composite-material blades, GE will test GE36-based blades. The GE36 open rotor engine was designed and flight-tested in the 1980s. It demonstrated 30-percent better fuel burn–compared to a ducted turbofan–thanks to a far higher bypass ratio. However, plummeting oil prices thwarted its commercial launch.

Running such “old” blades will provide GE with baseline data for flight-test correlation. Knowing how GE36 blades behaved on the ground and in flight, engineers will be able to predict how the new blades behave in flight. In Cleveland, NASA has refurbished the test rig that was used in the 1980s.

GE and the fundamental aeronautics program of NASA’s aeronautics research mission directorate are jointly funding the tests. Snecma will be involved in the blades’ design.