GE and NASA to give open-rotor jet engine systems a spin
By Jude Garvey
June 15, 2009
GE Aviation and NASA will run a wind tunnel test program over the northern summer to evaluate and test counter-rotating fan-blade systems for open-rotor jet engine designs. The newly improved rig for testing was originally used by GE and NASA in the 1980s on scale models of counter-rotating fan systems, which led to the development of the GE36 engine. The test program also demonstrated that an open-rotor jet engine consumed 30 percent less fuel compared to similar-sized conventional jet engines. Just think what a 30 percent drop in fuel consumption would deliver today, not only to an airline industry struggling to keep ticket prices down, but also the positive benefits to the environment.
GE is confident that the significant improvements to its computational aero-acoustic analysis tools, over the past 25-odd years, will make running the program a little easier this time around. Both GE snd NASA expect to gain a better analysis and understanding of open-rotor systems by testing a number of new and more sophisticated fan systems in the wind tunnel. Rather than running full engine tests, a number of configurations will be tested in simulated flight conditions. Factors such as aeronautical design and acoustic levels will be considered in terms of the actual operating environment.
"The tests mark a new journey for GE and NASA in the world of open rotor technology," says 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."
The wind tunnel facilities are located at NASA's Glenn Research Center in Cleveland, Ohio, and testing is expected to continue for the rest of this year and into early 2010. The tests will mirror those run in the 1980s, with the first tests using blades that were designed for the original GE36 jet engine.
The plan is to test six different blade designs in the wind tunnel. The designs will feature blades that are scaled to one-fifth the size of regular blades and will consist of two rows of counter-rotating blades. Blade efficiency and performance will be tested with the advanced computerized data acquisition systems during simulations, featuring high-altitude cruise conditions.
The main criticism of open-rotor jet engine design is the difficulty in reducing the amount of noise generated by these engines, particularly in commercial air space. Noise shielding or noise cancellation techniques may be required to ensure aircraft meet noise requirements. However, given the benefits of lower fuel cost to the airline industry and the positive impact on the environment, it may not be too long before aircraft of the future feature open-rotor jet engines.