Snecma courts RJ OEMs with DEM 21 turbofan

Aviation International News » August 2001
May 21, 2008, 9:17 AM

French engine manufacturer Snecma is developing a new high-pressure core for regional jet applications, dubbed DEM 21 for “21st century demonstrator,” in the 12,000- to 17,000-lb-thrust range. The program may provide the basis for variants capable of powering regional airplanes of up to 70 seats.

Snecma has scheduled the first core run for the first quarter of next year. According to Snecma’s market research, a demand for new engines in the regional airline industry remains strong.

“We started from studies we had for an alternative TP400 military turboprop core,” Michel Laroche, Snecma Motors’ vice president of engineering, told AIN. At the time, power requested for the European FLA military transport–now the Airbus A400M–may have evolved in such a way that a lower-power core may have proven necessary. Other contributions to DEM 21 come from the “platform for high-temperature tests” (PHT) program. PHT is a research core engine that achieved a turbine inlet temperature of 2,000 deg K. “This platform has given turbine technologies to DEM 21,” said Laroche. However, he would not disclose DEM 21’s turbine inlet temperature.

“After the first core test early next year, we plan to have the core mature later that year or early in 2003,” Laroche said. “This means meeting performance and durability goals.” He insisted Snecma is putting the core in a “realistic environment” to get a better picture of   real-world requirements.

DEM 21 will feature a six-stage compressor with at least an 11:1 pressure ratio, a low-emissions combustor and a single-stage turbine. “The combustor will be neither DAC nor TAPS,” said Laroche. The double annular combustor (DAC) is a CFM56 option on the Airbus A320 family, whereas a twin annular pre-swirl (TAPS) combustor is being developed under the Tech56 technology acquisition program by CFM partners Snecma and General Electric. Laroche just said injectors will be arranged in a “single-area layout” but will “meet specifications to get low emissions.”

The turbine will feature “advanced materials, such as single crystals,” Laroche said. Both compressor and turbine will benefit from 3-D fluid dynamics. To reduce costs of ownership, engineers will use “fewer vanes and blades per stage, bladed disks [blisks] and low-cost manufacturing techniques.”

A low-pressure spool that may be put together with the DEM 21 core “could use Snecma technologies developed for CFM applications. Asked about fuel-burn reduction, Laroche said, “Low NOx and low noise are top priorities.” However, an engine developed around DEM 21 would be “state-of-the-art in terms of fuel burn.”

When unveiling DEM 21, Snecma mentioned bullish market studies in the regional airline industry. According to the French engine manufacturer, these studies pointed “to the significant development potential of the air transport market” and “the emergence of new regional aircraft.”

In addition, Snecma found “a high probability of a requirement for new engines from multiple sources.”  Snecma wants a piece of the pie. “We are still in the process of watching the market, but we want to be there when it is time to make offers,” Laroche stressed.

Asked about possible competition with partner General Electric on regional jet engines, Laroche answered, “There is no competition as no program has been launched so far.” However, teams working on DEM 21 are separate from CFM teams “as it is a distinct task."

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