Quieter, lighter engine nozzles
4:13 PM on Oct 29, 2010
Ceramic matrix composites (CMC) are already finding their way into the core of new generation military turbofans such as the F136 JSF alternate engine, and are lined up for future commercial engines like CFM’s Leap X. Now COI Ceramics, a San Diego, Calif-based sister company to ATK, has won a Boeing contract to develop and demonstrate a CMC for use in another propulsion system application – the exhaust nozzle.The Boeing Research & Technology contract forms part of the FAA's Continuous Lower Energy, Emissions and Noise (Cleen) program and will lead to flight tests on a 737 in 2012, and a yet-to-be-determined twin-aisle testbed in 2013. CMC’s are lightweight, high-temperature composite materials which offer the potential for running engines at higher operating temperatures. This, in turn, improves combustion efficiency, leading to reduced fuel consumption. To-date much of the initial research focus for CMC application has centered on its use in the hot section where, thanks to the relatively low density of the material, the work so far suggests that dramatic weight reductions could be attained. CMCs, along with inter-metallic matrix (IMC) materials in the compressor, could reduce overall engine weight by as much as 50%. In a four-engined application, NASA-led research indicates this could translate into an overall aircraft weight reduction of almost 40%.As well as reducing weight, CMC in the exhaust nozzle is also expected to help in noise attenuation.
Credit: ATK/COI Ceramics
awt, ATK, Boeing, CLEEN, FAA