Abstract: Past methods and apparatus for manufacturing a rotor assembly have been used to provide rotor assemblies for rotating electric machines. Many of these electric machines rotate at low speeds. The present method and apparatus for manufacturing a rotor assembly can be used to make a rotor assembly to be used at high speeds. The rotor assembly includes a shaft having a frustoconical mounting surface defined thereon and having a plurality of magnets attached to the frustoconical mounting surface. A cover having a frustoconical inner surface surrounds the magnets and compressively secures the magnets to the shaft. The compressive forces applied by the cover and the adhesive used to secure the magnets insuring that a positive contact pressure exists between the magnets and the shaft during operation of the electric machine.

Abstract: Electric machines are used to produce electrical energy or are driven by electrical energy. Such machines include a stator assembly and a rotor assembly rotationally positioned within the stator assembly. A gap is formed between the rotating element and the stationary element. To increase the life and efficiency of many electric machines, heat formed within the gap is carried away by passing a cooling media through the gap. The present electric machine includes a cooling system wherein the electric machine is positioned in an inlet plenum of a gas turbine engine. Compressed air from the gas turbine engine is used to cool the gap of the electric machine. An expansion turbine is attached to the rotor assembly upstream of the gap and has high pressure gap cooling air directed through the expansion turbine into the gap to cool the electric machine.