GE Aviation (Booth No. 3900) is planning on testing the first full Passport 20 engine, slated to power the Bombardier Global 7000 and 8000, in the second quarter of next year. The design of the 16,500-pound-thrust turbofan was frozen in April this year. A series of thorough safety trials is well under way.
The Passport 20 features the largest fan blisk (blade-integrated disk) on a civil engine. It is made of titanium, but the case is constructed of composite materials. This new combination has necessitated many fan-blade-out rig tests, project manager Dennis King explained. Two of these tests focused on the blade rupture process and the containment characteristics of the fan case, and these were successful. A third test, “fan blade-out three,” is scheduled for the third quarter of next year. The testing will look at the overall product design, said Brad Mottier, GE Aviation vice president and general manager for business and general aviation.
Other recent rig tests include bird ingestion and one that measured the aerodynamic efficiency of the fan. GE has high expectations for the new fan, as the 18-blade blisk design was chosen to improve efficiency. In a conventional engine design, blades are separate parts, held by a slotted disk or pinned holes, and air can leak between blade platforms, causing a loss of performance. Blades also can shift back and forth in their slot or on their pin, which causes wear and vibration. But in a blisk, the blades and disk constitute one combined unit, which eliminates leaks, wear and vibration. In addition, the inner (hub) diameter can be made smaller, allowing for a greater airflow within the same fan outer diameter.
At the engine core level, two demonstrators of the high-pressure-ratio eCore have accumulated about 150 hours of testing.
The hardware for the first full engine is arriving at GE’s Evendale, Ohio facilities. The engine will be assembled in the first quarter of next year, as the first run is scheduled for the second quarter. In 2014, flight tests will be accomplished on GE’s flying testbed, a dedicated Boeing 747. Moreover, the company will employ the altitude test cell at the Arnold Engineering Development Center in Tullahoma, Tenn.
Eight engines and two cores will take part into the certification program. “There will be multiple builds of these engines,” King said. Engine certification is pegged for 2015.
The Passport 20’s 10-stage high-pressure (HP) compressor will include five blisk stages. “Increasing the number of HPC blisk stages from four to five is a design change that was introduced approximately one year ago,” a GE spokesman explained. The HP compressor will offer a stall-free design with no throttle restriction. Downstream from the combustor, the two-stage HP turbine will be followed by a four-stage low-pressure (LP) turbine. The LP turbine will feature third-generation 3-D aerodynamic design, state-of-the-art cooling techniques and active clearance control for reduced weight and enhanced durability.
As a result, GE claims the engine will offer “at least 8 percent improved specific fuel consumption, compared to current engines in the field.” It will be certified to CAEP/8 environmental standards with margins on all emissions (nitrous oxide, smoke, hydrocarbons and carbon dioxide), according to GE. As for noise, ICAO’s Stage 4 limits should be met with about a 13 EPNdB margin.
The Passport engine family could span the 12,000- to 20,000- pound thrust range. The Passport 20 will be certified at 18,200 pounds, although Bombardier’s thrust requirement is only 16,500 pounds.