GE's Passport 20 Engine Is On Time To Power New Globals
Development is well under way for GE Aviation’s 16,500-pound-thrust GE Passport 20 engine, which is set to power the Bombardier Global 7000 and 8000 business jets. The first engine is to begin ground testing in the second quarter of next year.
GE Aviation (Stand 1143) is anticipating certification of its new turbofan in 2015 and entry into service in 2016. A key feature of the new turbofan is the 52-inch-diameter fan bladed disk (blisk). “We have been running validation testing on two fan blisks, and the results have been very positive,” a spokesman told AIN. The manufacturer also plans to conduct blade-out, icing and aeromechanic trials on rigs at its Evendale, Ohio facility this year to verify design efforts.
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.
As the EBACE show approached, GE engineers were set to freeze the engine design. They had already released some component designs on longer-lead-time items such as forgings and tooling. Assembly of the first Passport 20 powerplant is to begin by year-end.
At the engine core level, two eCore demonstrators have accumulated about 150 hours of testing. “We are incorporating lessons learned into the eCore Demo 3,” the GE spokesman added. The eCore3 is scheduled to run later this year or next year.
The Passport 20’s 10-stage high- pressure (HP) compressor will include four blisk stages. Downstream from the combustor, the two-stage HP turbine will be followed by a four-stage LP turbine.
The HP compressor will offer a stall-free design with no throttle restriction. 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.
The integrated propulsion system is being developed by France-based Nexcelle, which is a joint venture between GE’s Middle River Aircraft Systems business and Safran’s Aircelle division. The result will be a long-duct mixed-flow design with an outer opening cowl made from composites, which should reduce weight and ease access to line-replaceable units. The one-piece structure will also reduce vibrations and will be acoustically treated for lower noise on the ground and inside the cabin.
As a result, GE claims the engine will offer “at least eight percent improved specific fuel consumption, compared to current engines in the field.” It will be certified to CAEP/8 environmental standards with margin 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.