The Boeing Co. (Chicago, Ill.) reported on Sept. 5 that it has successfully flight tested an innovative jet engine nozzle made of a ceramic matrix composite (CMC). Designed to reduce noise, weight and reduce fuel use, the CMC nozzle was taken through a series of tests aboard Boeing’s ecoDemonstrator 787 Flight Test Airplane. The regime included community noise testing, during which the plane was flown over a large acoustic array in Moses Lake, Wash. Boeing engineers have been working on the technology during the past five years, says Mitch Petervary, the technology’s principal investigator. Seeing all their hard work come to fruition, he noted, was gratifying. “This program began years ago with small samples in labs, and now we have flight-tested the largest oxide CMC structure in the world, and it performed at a very high level,” Petervary says. “Our innovative team has worked so hard to get to this point. Seeing our technology in the sky is remarkable and is a testament to what we can achieve.” This flight demonstration is part of the five-year U.S. Federal Aviation Admin. (FAA) Continuous Lower Energy, Emissions and Noise (CLEEN) program. Boeing is one of five industry contractors participating in CLEEN, an open, competitively bid, cost-sharing program focused on speeding development of new technologies that improve airplane fuel efficiency and decrease volatile emissions and noise.
“The FAA CLEEN Program is very excited to see Boeing’s ceramic matrix composite exhaust nozzle fly,” says Arthur Orton, FAA CLEEN program engineer. “The flight test of the CMC nozzle is a major milestone for this technology. Innovative technologies such as this are needed to help meet FAA’s NextGen environmental goals, and represents excellent progress for the CLEEN Program.” Modern engines have higher operating temperatures to achieve improved fuel efficiency and reduce emissions. However, these hotter temperatures are pushing the capabilities of currently used metallic components. According to its proponents, CMC technology is not only lighter than current metallic components but also can last longer at higher temperatures. Moreover, special CMC designs are amenable to having acoustic treatments built into them that help make engines quieter, lighter and more efficient. The technology also could enable new, dramatically different engine designs in the future.
The ecoDemonstrator test plane is employed by researchers in Boeing’s development and test program of the same name, which focuses on improving environmental performance by bringing new technologies, materials and methods to implementation faster than ever before.
