The invention relates to a method for modifying a multistage compressor. It further relates to a compressor modified according to the specified method and to a gas turbo group which comprises a compressor thus modified.
A modification of turbocompressors may take place in that the blade angle of blade rows is varied while the profile of the blade leaves remains constant. The blade angle is in this case normally defined as the angle which the chord of the profile forms with the circumferential direction of the compressor. By virtue of this possibility of varying the geometry of a blade cascade, for example, the mass flow can be increased without a redesign of the blade leaf being required. This is implemented, for example, in the case of adjustable compressor guide blade rows and, in particular, in the case of an adjustable entry guide blade row of a compressor. However, the implementation of a plurality of adjustable guide blade rows is comparatively complicated.
The invention relates to a method for increasing the absorption capacity in a multistage compressor. The compressor including rotor blades of a first compressor rotor blade row with a defined blade leaf profile. The rotor blades having a predetermined blade angle in a flow direction. Blades of at least one further blade row are arranged downstream of a second compressor stage having a defined blade leaf profile and, in the flow direction, a predetermined blade angle. The compressor rotor blade row and the at least one further blade row are arranged downstream of the second stage, include unchanged blade leaf profiles, and operate with a different blade angle, as compared with the predetermined blade angles. The blade angles of the at least one further blade row are selected as a function of the blade angle, modified for a greater absorption capacity, of the first compressor rotor blade row.
The invention also relates to a device for increasing an absorption capacity in a multistage compressor. The compressor including rotor blades of a first compressor rotor blade row with a defined blade leaf profile. The rotor blades having a predetermined blade angle in the flow direction. The blades of at least one further blade row arranged downstream of the compressor stage having a defined blade leaf profile and, in the flow direction, a predetermined blade angle. The compressor rotor blade row and at least one further blade row are arranged downstream of the second compressor stage and have unchanged blade leaf profiles and a different blade angle, as compared with the predetermined blade angles. The blade angles of the at least one further blade row are selected as a function of the blade angle modified for a greater absorption capacity, of the first compressor rotor blade row.
The invention further relates to a device for increasing an absorption capacity in a multistage compressor. The compressor including rotor blades of a first compressor rotor blade row with a defined blade leaf profile. The rotor blades have a predetermined blade angle in the flow direction, and blades of at least one further blade row are arranged downstream of a second compressor stage and have a defined blade leaf profile and, in the flow direction, a predetermined blade angle. The compressor rotor blade row and the at least one further blade row are arranged downstream of the second compressor stage and have, unchanged blade leaf profiles and a different blade angle, as compared with the predetermined blade angles. The blade angles of the at least one further blade row are selected as a function of the blade angle, modified for a greater absorption capacity, of the first compressor rotor blade row.
Further advantageous and expedient developments of the invention become clear to a person skilled in the art in light of the subclaims and of the exemplary embodiment illustrated below.
The method specified above is explained in more detail below with reference to an exemplary embodiment illustrated in the drawing in which, in particular,
Particulars which are not essential for understanding the invention have been omitted. The exemplary embodiment and the drawing are to serve for a better understanding of the method described above and are not to be cited in order to restrict the invention characterized in the claims.
According to one aspect of the invention, a method for modifying a multistage compressor by the staggering of blades, that is, the varying of the blade angle, is set forth where the blade leaf profile is maintained. According to a more specific aspect of the invention, this possibility is to be specified without adjustable blade rows being used. According to another aspect of the invention, the mass flow of the compressor is increased, in one exemplary embodiment, by up to six percent, as compared with a compressor before modification. In a more particular embodiment, the increase in the mass flow is to be achieved without the flow stability in the compressor being reduced or without giving rise to flow blockages in the blade ducts on account of the increased mass flow.
The method involves exchanging the rotor blades of the first compressor blade row for modified rotor blades which have an identical blade leaf profile to and a different blade angle than the rotor blades originally installed. The absorption capacity of the first compressor rotor blade row can thereby be increased and, in particular, in conjunction with an adjustable entry guide blade row, the compressor mass flow can be increased. Furthermore, a potentially impaired flow stability accompanying the modified geometry of the blade cascade is counteracted in that the blade angle of at least one blade row arranged further downstream and, in particular, downstream of the second compressor stage is modified. For this purpose, the blades of the at least one further blade row are exchanged for modified blades which have an identical blade leaf profile to the original blades and the blade angle of which is different from that of the original blades. In one embodiment of the invention, the variation of the blade angle in the further blade row is codirectional to the variation of the blade angle in the first compressor rotor blade row, that is to say, when the blade angle of the first compressor rotor blade row is increased, the blade angle of the further blade row is also increased, and, when the blade angle of the first compressor rotor blade row is reduced, the blade angle of the further blade row is also reduced. In one embodiment of the invention, the blade geometry of the guide blade row of the first compressor stage is maintained, unchanged, that is, neither the blade leaf profile nor the blade angle are modified.
The term “compressor stage” is to be understood in this context as meaning the arrangement of a compressor rotor blade row and of a compressor guide blade row following downstream. This is to be understood in contrast to a turbine stage which comprises a guide blade row with a rotor blade row arranged downstream of it. A rotor blade row, or moving blade row, comprises a blade ring or blade cascade which comprises a plurality of rotor blades. These are also designated as rotor components, for example rotor blading, a rotor blade ring or rotor blade cascade or the like. A guide blade row comprises a blade ring or a blade cascade which comprises a plurality of guide blades. These are also designated as stator components, for example stator blading, a stator blade ring or stator blade cascade and the like.
One development of the method specified here involves exchanging the rotor blades of the second compressor rotor blade row for modified rotor blades which have an identical blade leaf profile to the original rotor blades and a blade angle which is different from that of the original rotor blades. One embodiment of this development involves maintaining, unchanged, the blade geometry of the guide blade row of the second compressor stage.
Developments of the method described here involve, in at least one compressor stage arranged downstream of the second compressor stage, exchanging both the blades of the rotor blade row and the blades of a guide blade row for modified blades which have an identical blade leaf profile to the original blades and a blade angle which is different from that of the original blades, and/or exchanging the blades of at least one blade row of each compressor stage arranged downstream of the second compressor stage for modified blades which have an identical blade leaf profile to the original blades and a blade angle which is different from that of the original blades.
In one embodiment of the method, the blade angles in the blade rows, the blades of which are exchanged for modified blades, are adapted to one another in such a way that the relative enthalpy build-up, in relation to the total enthalpy build-up in the compressor, in the individual compressor stages and/or in the individual blade rows is kept essentially constant, as compared with the unmodified compressor. It is consequently possible to vary the mass flow of the compressor and at the same time to maintain, essentially unchanged, the stability reserve against stall.
An increase in the blade angle, which is defined as the angle which the chord of the blade leaf profile forms with the circumferential direction of the compressor, results generally in an increase in the mass flow. An application of the method described here, in which originally installed blades are exchanged for modified blades in which the chords of the blade leaf profiles are oriented in the direction of the compressor axis to a greater extent than in the case of the originally installed blades, consequently results in an application of the method for increasing the compressor mass flow. By means of an exemplary embodiment of the method, an increase in the compressor mass flow of up to six percent can be achieved without the stability reserve of the compressor being appreciably changed.
The refinements of the method which are described above may be combined with one another.
The invention further comprises a compressor which is modified by means of the method described above. Such a compressor comprises, in particular, at least two axial compressor stages and, in a more specific embodiment, is a purely axial multistage compressor. Purely axial multistage turbocompressors are used, for example, as compressors of gas turbo groups; the invention also to that extent comprises a gas turbo group which has a compressor modified by means of a method described above.
Although not mentioned explicitly, it is obvious to a person skilled in the art that the illustrations given above can be applied in a similar way to compressor bladings in which the blade leaf profiles are variable over the blade height and in particular also for twisted blades familiar to a person skilled in the art; the illustrations in
Number | Date | Country | Kind |
---|---|---|---|
05100201 | Jan 2005 | EP | regional |
This application is a continuation of International Application No. PCT/EP2006/050172, filed Jan. 12, 2006, which is incorporated by reference as if fully set forth.
Number | Name | Date | Kind |
---|---|---|---|
2705590 | Lovesey et al. | Apr 1955 | A |
2990106 | Craig | Jun 1961 | A |
2999668 | Howald et al. | Sep 1961 | A |
3428244 | Palmer | Feb 1969 | A |
4252498 | Radcliffe et al. | Feb 1981 | A |
Number | Date | Country |
---|---|---|
1080026 | Aug 1967 | GB |
Number | Date | Country | |
---|---|---|---|
20080260516 A1 | Oct 2008 | US |
Number | Date | Country | |
---|---|---|---|
Parent | PCT/EP2006/050172 | Jan 2006 | US |
Child | 11775936 | US |