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NASA is currently involved in the Aircraft Energy Efficiency Program (ACEE) which is directed toward developing technology for more fuel efficient aircraft. As part of this overall program, the Engine Component Improvement (ECI) Project was formulated to address near-term improvements for current engines. One part of this effort is Engine Diagnostics which is directed at investigating the causes for in-service performance deterioration of the CF6 and JT9D high bypass ratio turbofan engines. The other part is Performance Improvement, which is directed at development of component technologies to reduce the fuel consumption of CF6, JT9D and JT8D engines. This paper discusses the Performance Improvement part. Nine of sixteen concepts being developed under the ECI project are now complete and four are in service. The remaining five are being offered to the airlines.

Jet Engines may experience severe vibration due to the sudden imbalance caused by blade failure. This research investigates employment of on board magnetic bearings or piezolectric actuators to cancel these forces in flight. This operation requires identification of the source of the vibrations via an expert system, determination of the required phase angles and amplitudes for the correction forces, and application of the desired control signals to the magnetic bearings or piezo electric actuators. This paper will show the architecture of the software system, details of the control algorithm used for the sudden imbalance correction project described above, and the laboratory test results.

The steady-state and dynamic performance of a candidate aircraft power distribution system is considered. The system features distribution of both single phase 20-kHz and three-phase 400-Hz power. It is shown that unlike some other recent 20-kHz systems, the power quality of the 20-kHz bus is not a concern due to the use of a synchronous bi-directional rectifier (SBR) as the primary interface to the 20-kHz bus. In addition to showing that the system behaves adequately in the steady-state, the dynamic performance of the system is considered during step changes in load, bolted faults, and sudden variations in jet engine speed.