Preparation of a CFM56-5B dual spool test.
The current CFM56-5C.
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Major component testing is under way as the validation phase of CFM International's Project TECH56 moves into its next phase. The project, which is in its third year, is a technology acquisition program designed to develop and validate advanced technology for the CFM56 family of aircraft engines. The technology could serve as the basis for a new or derivative engine, as well as upgrades to the current product line. CFM International is a 50/50 joint company between Snecma Moteurs of France and General Electric of the U.S.
CFM has already completed performance, operability, and aeromechanical testing of the first new six-stage high-pressure compressor design. According to the company, preliminary results look very promising, with the target stall margin demonstrated. A second test compressor of this design is on track to begin testing in the third quarter of this year.
The TECH56 high-pressure turbine "aero" design completed 75 h of testing in May. The company will soon run the first dual spool rig test, which mates the new high-pressure turbine design with a redesigned low-pressure turbine, to validate the improved interaction. It expects the design to provide significant efficiency gains and result in a 1% fuel burn improvement. Additional dual spool rig tests are scheduled for later this year, including the counter-rotating turbine design.
At time of press, full annular rig testing of the advanced Twin-Annular Pre-Swirl (TAPS) combustor was scheduled to begin, with a full engine demo scheduled for the fourth quarter of this year. The TAPS combustor will maintain the NOx emissions reductions the company achieved with its double annular combustor while further reducing carbon monoxide and unburned hydrocarbon emissions.
Brush seal technology developed as part of TECH56 is being validated in sub-scale and full-size component tests. The brush seals, which provide higher efficiency, reduced losses, and reduced deterioration, will undergo full-engine tests in the first half of 2001.
The company has also completed testing of a 61-in solid, swept wide-chord fan blade with excellent results. It is now developing a hollow 68-in swept wide-chord fan. This design will complete full-scale performance, crosswind, acoustic, and blade-out testing early next year. Swept wide-chord blades provide significant thrust growth fans of similar diameter coupled with fuel burn improvements.
CFM has also reached an agreement with Airbus Industrie to develop an advanced version of the CFM56-5C4 engine, the CFM56-5C Enhanced, to power the new Airbus A340-300 Enhanced. This new engine will incorporate the 3-D aero compressor and high-pressure turbine originally developed for the CFM56-5B/P core, which has logged more than 6 million hours in service, including more than 2.4 million hours powering the Airbus A320 family. A new stage-one low-pressure turbine nozzle is being developed to transition into the engine's current low-pressure turbine.
Design objectives for the engine include a 1% improvement in specific fuel consumption compared to the CFM56-5C4, in addition to more than 10°C improvement in exhaust gas temperature (EGT) margin. This additional margin is projected to result in maintenance cost reductions of up to 10%. The engine will maintain the current CFM56-5C noise signature, which, according to CFM, is the quietest in its class. The current CFM56-5C-powered A340 meets all current noise regulations with a cumulative margin of 23 EPNdB (effective, perceived noise in decibels). The company is scheduled to begin testing on its first engine by late 2001, with aircraft certification and entry into service by 2003.
In addition to offering the CFM56-5C Enhanced for the new A340-300 Enhanced, CFM is also planning to offer an upgrade kit incorporating this new hardware to current A340s with availability forecast for late 2003.
Frank Bokulich
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Aerospace Engineering September 2000
