This claims the benefit of European Patent Application EP 121 549 29.9, filed Feb. 10, 2012 and hereby incorporated by reference herein.
The invention relates to a turbomachine.
The maximum deflection of a row of blades of a turbomachine and thus its aerodynamic load capacity are limited, for one thing, by a separation of the flow along the blade profile. For another thing, the maximum deflection is limited by a separation of a boundary-layer flow on the side walls on the hub side and on the housing side. Double-row blade arrangements are known for purposes of increasing the deflection capacity of rows of blades. A prior-art turbomachine having such an arrangement is shown in
However, it has been found that, in the side wall area, that is to say, in the area of the hub 2 and/or of the housing 4, the influence of the boundary layer calls for blade contouring that diverges from the center 34 of the main flow path, and by means of this contouring, the flow conditions in the side-wall area that differ from those of the center 34 of the main flow path can be taken into account. Therefore, when it comes to blade-row groups, European patent application EP 2 261 463 A2 proposes to set a meridional distance between the trailing edges of the front blades and the leading edges of the rear blades in such a way that this distance increases from the center of the main flow path in the direction of a side wall on the hub side or housing side.
It is an object of the present invention to provide a turbomachine with optimized flow characteristics.
The present invention provides a turbomachine comprising at least one blade-row group that is arranged in the main flow path and at least two rows of blades that are adjacent to each other in the main flow direction, each row having a plurality of blades. According to the invention, the turbomachine has a narrow cross section and a degree of overlap between the blades of the upstream row of blades and the blades of the downstream row of blades which vary starting at the center of the main flow path in the direction of at least one main flow limiting means.
Owing to the narrow cross section and to the degree of overlap which vary starting at the center of the main flow path in the direction of at least one main flow limiting means, the positioning of the blades relative to each other and their interaction are adapted to the main flow in the side wall area, thus promoting a separation-free flow through the rows of blades. Due to the inventive radial change of the blade arrangement, namely, of the narrow cross section formed by two blades as well as its degree of overlap on the suction side and/or on the pressure side, changed boundary conditions of the flow in the side wall area are taken into account and separations of the flow in the side wall area are reduced. The inventive configurations of the narrow cross sections and of the degrees of overlap can be employed for any type of blades. Examples are rotors with a clearance band or a shroud band, stators with a clearance, half clearance or without a clearance as well as variable stators.
In one embodiment, the narrow cross section increases steadily in the direction of the main flow limiting means.
In this context, the narrow cross section can increase in the direction of the main flow limiting means and can then decrease.
As an alternative, the narrow cross section can increase in the direction of the main flow limiting means and can then remain constant.
In another embodiment, the narrow cross section decreases steadily in the direction of the main flow limiting means.
In this context, the narrow cross section can decrease in the direction of the main flow limiting means and can then increase.
As an alternative, the narrow cross section can decrease in the direction of the main flow limiting means and can then remain constant.
In one embodiment, the degree of overlap increases steadily in the direction of the main flow limiting means.
In this context, the degree of overlap can increase in the direction of the main flow limiting means and can then decrease.
As an alternative, the degree of overlap can increase in the direction of the main flow limiting means and can then remain constant.
In another embodiment, the degree of overlap decreases steadily in the direction of the main flow limiting means.
In this context, the degree of overlap can decrease in the direction of the main flow limiting means and can then increase.
As an alternative, the degree of overlap can decrease in the direction of the main flow limiting means and can then remain constant.
The narrow cross section and the degree of overlap can vary starting at the center of the main flow path in the direction of both main flow limiting means.
In this context, the narrow cross section and the degree of overlap can have identical or varying configurations in the direction of the main flow limiting means.
Other advantageous embodiments of the invention are the subject matter of additional subordinate claims.
Preferred embodiments of the invention will be explained in greater detail below on the basis of schematic depiction. The following is shown:
Below, identical structural elements preferably have the same reference numerals whereby, for the sake of clarity, only a few of the elements are provided with reference numerals.
As is shown in the detailed view A in
In this embodiment, the narrow or narrowest cross section Dmin is determined by ascertaining the smallest distance (circle having the smallest radius) between a pressure side 46 of the front blades 38 and a suction side 48 of the rear blades 40. Since the blades 38, 40 are positioned like nozzles with respect to each other, the narrow cross section Dmin is close to the trailing edges 42 of the front blades 38 and far from the leading edges 44 of the rear blades 40.
Owing to the inventive radially variable positioning of the front and rear rows of blades, it is possible for the narrow cross section Dmin to be in a plane between the pressure side 46 of the front row of blades and the suction side 48 of the rear row of blades, but to then increase in the direction of another plane to such an extent that the rear row of blades is actually closer to the suction side 48 of the front row of blades. The examples of configurations shown in the figures below always refer to a specific side of the blade.
The degrees of overlap ODS and OSS are determined separately for the pressure side 46 and for the suction side 48. Each row of blades has a degree of overlap ODS and OSS on the pressure side and on the suction side, respectively, whereby preference is given to the degree of overlap ODS, OSS that is formed with the blade surface 46, 48 that is closer.
The degree of overlap ODS on the pressure side is ascertained by lowering a plumb line 50a from the leading edge 44 of the rear blade 40 onto a skeleton line 52a of the front blade 38.
The distance between the trailing edge 42 of the front blade 38 and the point of intersection between the plumb line 50a and the skeleton line 52a is the degree of overlap ODS.
The degree of overlap OSS on the suction side is ascertained by lowering a plumb line 50b from the trailing edge 42 of the front blade 38 onto a skeleton line 52b of the rear blade 40. The distance between the leading edge 44 and the point of intersection between the plumb line 50b and the skeleton line 52b of the rear blade 40 is the degree of overlap OSS.
Fundamentally, the degrees of overlap ODS, OSS are ascertained to be positive from a given edge 42, 44 in the direction of the corresponding blade 40, 38. In the embodiment shown, the degrees of overlap ODS, OSS consequently have positive values (ODS>0, OSS>0), whereby the degree of overlap ODS on the pressure side acquires smaller positive values than the degree of overlap OSS on the suction side (ODS<OSS). As has been sketched in
In
In this embodiment, the narrow cross section Dmin is determined each time between the suction side 48 of the front row of blades and the pressure side 46 of the rear row of blades. Since the blades 38, 40 are positioned like diffusers with respect to each other, the narrow cross section Dmin is located close to the leading edges 44 of the rear blades 40 and thus far from the trailing edges 42 of the front blades 38.
The degrees of overlap ODS, OSS have positive values (ODS>0, OSS>0) whereby, corresponding to the previous embodiment according to
The degree of overlap ODS on the pressure side is ascertained by lowering a plumb line 50a from the trailing edge 42 of the front blade 38 onto a skeleton line 52b of the rear blade 40. The distance between the leading edge 44 and the point of intersection between the plumb line 50b and the skeleton line 52b of the rear blade 40 is the degree of overlap OSS.
The degree of overlap OSS on the suction side is ascertained by lowering a plumb line 50b from the leading edge 44 of the rear blade 40 onto a skeleton line 52a of the front blade 38. The distance between the trailing edge 42 of the front blade 38 and the point of intersection between the plumb line 50b and the skeleton line 52a is the degree of overlap OSS.
The degree of overlap ODS on the pressure side is ascertained by lowering a plumb line 50a from the leading edge 44 of the rear blade 40 onto the extrapolated skeleton line 52a of the front blade 38. The distance between the trailing edge 42 of the front blade 38 and the point of intersection between the plumb line 50a and the extrapolated skeleton line 52a is the degree of overlap ODS.
The degree of overlap OSS on the suction side is ascertained by lowering a plumb line 50b from the trailing edge 42 of the front blade 38 onto the extrapolated skeleton line 52b of the rear blade 40. The distance between the leading edge 44 and the point of intersection between the plumb line 50b and the extrapolated skeleton line 52b of the rear blade 40 is the degree of overlap OSS.
As can be seen in
The narrow cross section Dmin, as shown in the left-hand depiction, can be linear and, for instance, can increase steadily (straight line 58). By the same token, it can be linear and decrease steadily (straight line 60).
As is shown in the depiction in the middle, the narrow cross section Dmin can likewise acquire curved configurations and, for example, can decrease from the center 54 of the main flow path in the direction of the main flow limiting means 56 over an area of the radial height, and can then remain constant over a height area (curve 62).
As is shown in the right-hand depiction, the narrow cross section Dmin can also increase or decrease only over a height area in the direction of the main flow limiting means 56, and can then once again increase or decrease over a height area, and/or can be constant over a remaining height area. For instance, reference is hereby made to the S-shaped line 64 which decreases starting at the center 54 of the main flow path in the direction of the main flow limiting means 56 over a height area, after which it increases over a height area, and it finally decreases again over a height area.
The narrow cross section Dmin can vary starting at the center 54 of the main flow path in the direction of the main flow limiting means 56, whereby it can have different configurations in the direction of the main flow limiting means on the hub side and in the direction of the main flow limiting means on the housing side.
As can be seen in
As is shown in the left-hand depiction according to
As is shown in the right-hand depiction in
As is shown in the depictions according to
The degree of overlap OSS or the degrees of overlap OSS, ODS can vary starting at the center 54 of the main flow path in the direction of the two main flow limiting means 56, whereby it/they can have different configurations in the direction of the main flow limiting means on the hub side and in the direction of the main flow limiting means on the housing side.
This document discloses a turbomachine having at least one blade-row group that is arranged in a main flow path and at least two adjacent rows of blades that are adjacent to each other as seen in the main flow direction, each row having a plurality of blades 38, 40, whereby a narrow cross section and at least one degree of overlap between the blades of the upstream row of blades and the blades of the downstream row of blades vary starting at the center of the main flow path in the direction of at least one main flow limiting means.
Number | Date | Country | Kind |
---|---|---|---|
12154929 | Feb 2012 | EP | regional |
Number | Name | Date | Kind |
---|---|---|---|
1889717 | Warfel | Nov 1932 | A |
2314572 | Chitz | Mar 1943 | A |
2938662 | Eckert | May 1960 | A |
2982361 | Rosen | Mar 1961 | A |
3075743 | Sheets | Jan 1963 | A |
3606579 | Mehus | Sep 1971 | A |
3692425 | Erwin | Sep 1972 | A |
3767324 | Ericson | Oct 1973 | A |
3830587 | Shipes | Aug 1974 | A |
3867062 | Troller | Feb 1975 | A |
3883264 | Gadicherlav | May 1975 | A |
3937592 | Bammert | Feb 1976 | A |
4512718 | Stargardter | Apr 1985 | A |
4913670 | Spranger | Apr 1990 | A |
5002001 | Spranger | Mar 1991 | A |
5236307 | Ng | Aug 1993 | A |
6099249 | Hashimoto | Aug 2000 | A |
7462014 | Chang | Dec 2008 | B2 |
7753652 | Truckenmueller | Jul 2010 | B2 |
8534997 | Guemmer | Sep 2013 | B2 |
20080298974 | Guemmer | Dec 2008 | A1 |
20100303629 | Guemmer | Dec 2010 | A1 |
20120148396 | Guemmer | Jun 2012 | A1 |
Number | Date | Country |
---|---|---|
3237669 | Apr 1984 | DE |
0823540 | Feb 1998 | EP |
2261463 | Dec 2010 | EP |
2463480 | Jun 2012 | EP |
752674 | Jul 1956 | GB |
WO 2005040559 | May 2005 | WO |
Number | Date | Country | |
---|---|---|---|
20130209224 A1 | Aug 2013 | US |