Snecma Propulsion Solide, a SAFRAN group company specialized in solid propulsion and thermostructural composites for launchers and missiles, is showcasing a prototype exhaust mixer for the CFM56-5C engine. Located in the exhaust nozzle, where hot and cold gases are combined, this prototype is made of a ceramic matrix composite, or CMC.

“We were looking for new markets for our carbon and silicon carbide-based composite materials. Since we’re already a specialist in missile and launcher nozzles, we decided to apply these technologies to nozzles on commercial aircraft engines,” explains Alain Allaria, commercial engine exhaust manager at Snecma Propulsion Solide. “In 2003, along with Snecma and Aircelle, the SAFRAN group’s engine and nacelle manufacturers, respectively, we launched a technology demonstration program for a CFM56-5C CMC mixer prototype, to introduce thermostructural composites on commercial engines. Our aim is to offer the first applications by 2010.”

One of the main advantages of this type of part is weight savings. “A CMC nozzle mixer is 30% lighter than an equivalent steel part,” explains Alain Allaria. “CMCs also stand up to the high temperatures found in the CFM56 nozzle.” The CMC prototype shows that it is possible to make a part with a complex shape, that maintains its mechanical integrity at high temperatures. “Because of our expertise, we were able to produce the part very quickly, and it is extremely competitive with steel. We needed advanced design studies to resolve the engine integration problem and maintain good performance,” adds Allaria.

Snecma Propulsion Solide is the first manufacturer to produce a CMC mixer and carry out successful ground tests. The next step is a demonstrator, planned for 2007.