Axial flow machine having an asymmetrical compressor inlet guide baffle

Abstract

An axial flow machine having an asymmetrical air inlet and, downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes is characterized in that at least some of the guide vanes of the inlet guide baffle have a vane profile and / or an angle of attack that deviate(s) from the remaining guide vanes. The inlet flow angle of the first compressor stage is hereby evened out circumferentially symmetrically. This is accomplished in that the different inlet angles resulting at various circumferential positions of the inlet guide baffle due to the asymmetry of the air inlet, are influenced by selective profiling and / or by selectively modifying the angle of incidence of individual guide vanes in such a way that a circumferentially symmetrical outflow angle from the inlet vane ring results. In this way, the circumferential distortions caused by the asymmetrical air inlet are minimized and, thus, circumferentially symmetrical inlet conditions are passed onto the first compressor stage, which results in an improved stability and an enhanced efficiency of the compressor.

Description

The present invention relates to an axial flow machine having an asymmetrical air inlet and, directly downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes.BACKGROUNDSuch axial flow machines having an asymmetrical air inlet are used as core engines in the case of turboprop or helicopter engines, for example. The asymmetry of the incident flow of the first compressor stage can cause problems related thereto, which can lead to a partial flow separation at this vane stage, along with the surging and efficiency loss resulting therefrom.For stationary gas turbines, the European Patent Application EP 1 508 669 A1 teaches that, by forming different profile curvatures of at least two inlet guide vanes, it is possible to increase the efficiency of a stationary gas turbine. The increase in the efficiency is achieved by reducing the flow losses at the inlet guide baffle.SUMMARY OF THE INVENTIONIt is an object of the present invention to avoid the disadvantages...

AI Technical Summary

Benefits of technology

It is an object of the present invention to avoid the disadvantages of the known related-art approaches and to devise an improved approach for achieving the most symmetrical possible incident flow of the first compressor stage in the case of an axial flow machine having an asymmetrical air inlet.

An axial flow machine having an asymmetrical air inlet and, downstream therefrom, a compressor having an inlet guide baffle composed of guide vanes is provided in accordance with present invention, whereby at least some of the guide vanes of the inlet guide baffle have a vane profile and / or an angle of attack that deviate(s) from the remaining guide vanes. The inlet flow angle of the first compressor stage is hereby evened out circumferentially symmetrically. This is accomplished in that the different inlet angles resulting at various circumferential positions of the inlet guide baffle due to the asymmetry of the air inlet, are influenced by selective profiling and / or by selectively modifying the angle of incidence of individual guide vanes in such a way that a circumferentially symmetrical outflow angle from the inlet vane ring results. In this way, circumferential flow distortions caused by the asymmetrical air inlet are minimized and, thus, circumferentially symmetrical inlet conditions are passed onto the first compressor stage, which results in an improved stability and an enhanced efficiency of the compressor. There may, for example, be a main guide vane group in the guide baffle that has only some individual vanes that differ from those of the group.

One advantageous specific embodiment of the present invention provides that individual guide vane groups have a vane profile and / or angles of attack that deviate(s) from the remaining guide vanes. This makes possible an efficient production and the cost savings associated therewith. The guide vanes may be configured in a plurality of groups having different geometries, for example.

Another advantageous specific embodiment of the present invention provides that the guide vanes have an adjustable design. The desired effect may likewise be achieved by variably adjusting at least individual vanes or vane groups, since this makes it possible to quasi selectively re-stagger individual vanes. Here, the advantage is also derived that, in the case that the flow conditions change, it is possible to correct the individual orientation of the guide baffle.

Another advantageous specific embodiment of the present invention provides that one individual control be provided in each case for some or all of the guide vanes. This makes it possible to individually correct in the case of altered flow conditions.

Problems solved by technology

The asymmetry of the incident flow of the first compressor stage can cause problems related thereto, which can lead to a partial flow separation at this vane stage, along with the surging and efficiency loss resulting therefrom.

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