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General Electric GE90
The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aviation for the Boeing 777, with thrust ratings ranging from . It entered service in November 1995. Currently the world’s largest turbofan engine, it is one of three options for the 777-200, -200ER, and -300, and the exclusive engine of the -200LR, -300ER, and 777F.
==Design and development==
The GE90 was launched in 1990. GE Aviation is associated with Snecma (France), IHI (Japan) and Avio (Italy). Developed from the 1970s NASA Energy Efficient Engine, the 10-stage high pressure compressor develops a pressure ratio of 23:1 (an industry record) and is driven by a 2-stage, air-cooled, HP turbine. A 3-stage intermediate pressure compressor, situated directly behind the fan, supercharges the core. The fan/IPC is driven by a 6-stage low pressure turbine.
The higher-thrust variants, GE90-110B1 and -115B, have a different architecture from the earlier marks of GE90, with one stage removed from the HP compressor (probably from the rear, to increase core size), with an extra stage added to the IP compressor to maintain/increase overall pressure ratio to achieve a net increase in core flow. General Electric performed a similar re-staging exercise when they upgraded the CF6 from the -6 to the higher thrust -50. However, this thrust growth route is expensive, since all the downstream components (e.g. turbines) must be larger (in flow capacity). As a result, GE sought (and received) sole engine supplier status with the -115B on the Boeing 777-300ER and the 777-200F that is usually de-rated to 110. The fan is an advanced, larger diameter unit made from composite materials and is the first production engine to feature swept rotor blades. Although the larger fan in itself would produce a higher static thrust, an increase in core size and, thereby core power, was required to improve the net thrust at normal flight speeds.
The GE90-115B is powerful enough to fully operate GE's Boeing 747 testbed on its own power, an attribute demonstrated during a flight test.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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