Pratt & Whitney has started a series of wind tunnel tests on a key component for a second-generation geared turbofan (GTF) engine with up to 50% higher bypass ratio.
The first-generation GTF with a 12:1 bypass ratio has already been selected on four narrowbody aircraft - Airbus A320neo, Bombardier CSeries, Irkut MS-21 and Mitsubishi Regional Jet.
But P&W already is developing a second-generation of the geared propulsor for an engine with a bypass ratio of between 15:1 and 18:1, says Alan Epstein, P&W vice president of technology and environment.
The new wind tunnel tests at a NASA facility are examining the propulsor flow path, including the inlets and the geared fan. P&W is studying a variety of designs that reduce the length of the inlet.
Inlets are now sized to provide noise attenuation, he explains. But the GTF architecture allows the fan to spin more slowly, which generates less noise.
"So I can afford in a noise budget sense to reduce the length of the nacelle," Epstein says.
The second-generation also will feature a new hot section with a reduced requirement for cooling flow, which reduces the thermal efficiency of the combustion process.
P&W is considering incorporating advanced metallics and ceramics into the high-pressure spool of the second-generation GTF, Epstein says, noting that an all-ceramic turbine section is not feasible for the next generation of turbofan engines.