Gas Turbine Engine With an Operating-Fuel Cooled Generator

The present invention relates to a gas turbine engine for an aircraft, and includes a compressor, a rotor shaft, and at least one turbine; a generator for supplying energy to auxiliary devices of the aircraft is arranged between the compressor and the turbine. The generator is driven by the rotor shaft, and comprises a generator housing, a generator stator, and a generator rotor; the generator is cooled by turbine fuel.

Gas turbine engines, which are used for temporary operation in pilotless aircraft, are distinguished by a very simple construction. For supplying power to the auxiliary devices of the aircraft, these gas turbine engines have a generator which is driven directly by the elongated rotor shaft which is mounted ahead of the compressor in the compressor hub. In so doing, the gas turbine engine is elongated, and, with regard to flow dynamics, the generator has a negative effect on the intake cross section of the compressor.

It has therefore already been proposed with one known gas turbine engine of the aforementioned general type to arrange the generator between the compressor and the turbine and to cool it with turbine fuel (ZTL-Studie 1978 der Klockner-Humboldt-Deutz AG "Schubtriebwerk fur kurze Lebensdauer ohne Getriebe fur Hilfsgerate" (thrust engine for brief duration without gearing for auxiliary devices), section 3.5.2 and FIG. 12). This generator arrangement and generator cooling, which was only addressed as a basic approach, involves considerable difficulties. The manufacturing cost of the gas turbine engine must not rise due to this altered overall construction and the then necessary cooling, and no negative effects on the supply of fuel to the combustion chamber must be produced.

It is therefore an object of the present invention to eliminate these problems, i.e. to ensure an intensive cooling of the generator stator, the generator rotor, as well as other possible parts of the gas turbine engine in the region of the rotor shaft, and to still have a simple and economical construction of the gas turbine engine.

This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in conjunction with the accompanying drawings.

FIG. 1 a schematic partial view of a gas turbine engine, and in particular is a longitudinal section of one inventive embodiment through a gas turbine housing, a rotor shaft bearing, and a schematically illustrated generator.

FIG. 2 shows the annular or ring-shaped structure of the heat exchanger; and

FIG. 3 shows further details regarding the supply of air to the turbine.

The gas turbine engine of the present invention is characterized primarily in that the generator housing is surrounded by a heat exchanger which, by means of a partition which essentially extends coaxial to the rotor shaft, divides the housing into two chambers through which cooling medium flows; of these chambers, an inner primary chamber has turbine fuel flowing therethrough, and an outer secondary chamber has compressor air flowing therethrough, with the cooled compressor air being adapted to be supplied via a direction-changing arrangement to the generator rotor and possibly to at least one rotor bearing.

The inventive heat exchanger, which radially surrounds the generator, intensively cools the generator stator by means of its primary chamber, through which turbine fuel flows. On the other side, this primary chamber borders on the secondary chamber via the partition; a partial stream of the compressor air is guided through this secondary chamber, so that the compressor air can be cooled under the effect of the convective heat transfer to the fuel, and is subsequently available for cooling the generator rotor and possibly the rotor shaft bearing.

Pursuant to one specific embodiment of the present invention, the heat transfer to the partition can be improved by the provision of ribs. These ribs can form helically extending cooling channels not only in the primary chamber but also in the secondary chamber.

To simplify manufacture and assembly, both sides of the partition can be provided with suitable ribs. During assembly of the gas turbine engine, the smooth generator housing is placed in the gas turbine housing, so that cooling channels are formed between the generator housing, the partition, and the ribs. The partition may be a part of the gas turbine housing. Furthermore, an insulated cover may be placed over the partition, so that cooling channels for the compressor air can be formed between this cover and the partition.

It is also possible to make the inner side of the partition smooth, and to provide the generator housing with radially projecting ribs which border on the smooth side of the partition, so that cooling channels for the fuel are available between the generator housing and the partition.

It is furthermore proposed, finally also to supply the partial stream of the compressor air which already serves for cooling the generator and the rotor shaft bearing to the wheel of the turbine for cooling the same. In this manner, a particularly favorable possibility for the cooling of the wheel results.

Referring now to the drawings in detail, a rotor shaft 1 of a gas turbine engine is shown. A partially illustrated compressor wheel 2, a generator 3 for supplying power to auxiliary devices, and a non-illustrated wheel of a turbine are arranged one after the other on the rotor shaft 1. The generator 3 has a housing 4, a stator 5, and a rotor 6. The rotor shaft 1 is mounted in the generator housing 4, for example by means of a bearing 7. Furthermore, the generator housing 4 is surrounded by a heat exchanger 8 which divides the housing 4 by means of a partition 9 into a primary chamber 10, through which turbine fuel flows, and a secondary chamber 11, through which compressor air flows. Ribs 12, which are unitary with the partition 9, project not only into the primary chamber 10, but also into the secondary chamber 11; these ribs 12 respectively form cooling channels 10a and 11a. As is also evident from the drawing, the partition 9 is part of a gas turbine housing 13 in which the generator housing 4 is placed. The ribs 12 on the outer side of the partition 9 are closed by an insulated cover 14 for the purpose of forming the cooling channels 11a. The gas turbine housing 13 and the generator housing 4 together form a direction-changing arrangement 15 for guiding cooled compressor air toward the generator rotor 6.

A partial stream of the compressor air, designated in the drawing with the reference symbol A, flows through the secondary chamber 11 of the heat exchanger 8 and is cooled by the turbine fuel which flows through the primary chamber 10 and from there by means of a fuel pump to a non-illustrated combustion chamber. This cooled compressor air is subsequently conveyed by the direction-changing arrangement 15 into the interior of the generator housing 4, where it cools the rotor shaft bearing 7, the generator rotor 6, and possibly a non-illustrated wheel of the turbine. In this manner, a particularly intensive cooling of the generator, the rotor shaft bearing, and possibly the turbine wheel can be achieved at little structural expense.

The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawing, but also encompasses any modifications within the scope of the appended claims.