GE Transportation - Aircraft Engines: The Cleanest and Quietest

GE has recently invested hundreds of millions of dollars in breakthroughs to make its engines more environmentally friendly. During the next two years, the regulatory agencies overseeing airport noise and aircraft emissions are implementing more stringent limits. Most of GE's current production engines already meet or fall well within these standards.

For future engine designs, GE is developing exotic new technologies -- from exhaust nozzles to advanced combustor concepts -- that will meet even tougher requirements long before they become law. Anticipating increasingly stringent noise and emission limits has been an inherent part of GE's technology and design strategy.

When airlines wanted lower oxides of nitrogen (NOX) emissions for their new Airbus A320 series and Boeing 737 aircraft, GE was in a position to introduce the double-annular combustor (DAC) for the best-selling CFM56 engine, which is manufactured by CFM International, a 50/50 joint company of GE and Snecma Moteurs of France. Developed initially through NASA and GE technology programs, the DAC burns fuel at lower temperatures in two stages, instead of the single stage in conventional combustors, to radically reduce NOX levels.

Building upon this technology, GE has launched the development of a new concept: the twin-annular, premixing swirler (TAPS) combustor. In development tests, this unique combustor has significantly lowered NOX to levels even lower than the DAC, in a package that delivers improved performance and lower cost and weight.

Across GE's engine models, GE has improved the process by which air and fuel are mixed in the combustor to produce industry-leading low-emission levels on various commercial aircraft—from jumbo jets to the new regional jets.

While leading the charge to lower jet engine emissions, GE is also reducing aircraft noise.

A significant part of aircraft noise is created by the propulsion system, and GE is investing in advanced fan designs and components that reduce engine noise.The GE90 engine for the Boeing 777 is a classic case. Its fan blades, the largest in aviation, create an unprecedented amount of air flow through the engine to drastically improve fuel efficiency. Coupled with the world's highest pressure ratio compressor, the GE90's large fan blades are able to rotate slower -- producing the lowest noise of any engine powering jumbo jets. Also, the engine's exhaust air moves at very low speed, so the noise it produces when mixed with the atmosphere is much less. The GE90 will meet the strictest noise standards for many years to come.

After years of development work, GE will introduce later this year a new exhaust nozzle into airline service that will significantly reduce jet noise. Called the chevron nozzle, it improves the mixing of exhaust gases in the back of the engine. The chevron nozzle, yet another technology first for GE, will be a feature on the new CF34 engines powering the new regional jets entering passenger service over the next three years.