WO2009127204A1

WO2009127204A1 - Stator and/or rotor stage of an axial compressor of a turbo machine having flow guide elements for increasing efficiency

Info

Publication number: WO2009127204A1
Application number: PCT/DE2009/000534
Authority: WO
Inventors: Karl Engel
Original assignee: Mtu Aero Engines Gmbh
Priority date: 2008-04-19
Filing date: 2009-04-18
Publication date: 2009-10-22
Also published as: DE102008019740A1

Abstract

The invention relates to a stator and/or rotor stage of an axial compressor of a turbo machine having at least one blade (1) configuring an intake side and a pressure side connected to the inner side of an external wall (2) at at least one radial end and/or the outer side of a hub (4), and having at least one transverse fin (3, 3’) extending from the corresponding outer wall and/or hub into a flow volume, at a distance from and opposite to the intake side of the blade. According to the invention, the transverse fin is configured as one piece with the outer wall and/or the hub, preferably by milling.

Description

Stator and / or rotor stage of an axial compressor of a turbomachine with flow guide to increase efficiency

description

The present invention relates to a stator and / or rotor stage of an axial compressor of an axial flow machine, which comprises at least one stator / rotor blade, which has a suction side and a pressure side.

In axial flow machines alternately rotor and stator stages are arranged in an axial compressor. In this case, an attempt is made to achieve the highest possible pressure build-up in each stage in order to increase the efficiency of the turbomachine. For this purpose, an individual profile design of stator / rotor blades is anticipated. The respective profile is determined in such a way that a forming flow on the stator / rotor blade remains in a working area corresponding to the design of the turbomachine. However, the blades are bounded laterally by walls, namely a housing wall formed outer wall and a hub forming inner wall. On these walls, relatively thick flow boundary layers form, especially in the middle and high-pressure compressor area. These increased boundary layer thicknesses and the resulting pressure increases in stator / rotor stages of axial compressors are responsible for premature termination of the flow on the sidewalls. It should be noted that in axial compressors about 60% of the losses caused by flow separation, in particular on the walls of the housing and hub.

In general, a stator / rotor stage of an axial compressor comprises a plurality of circumferentially uniformly spaced stator / rotor blades, which are arranged to each other such that the suction side of a stator / rotor blade of the pressure side of each adjacent further stator / rotor blades. Turns rotor blade. In such a stator / rotor stage, a thickness of a flow wall boundary layer grows in the region of the respective stator / rotor blade. This is due to the fact that the axial main flow is delayed by a profiling of the stator / rotor blade. In addition, between each two adjacent stator / rotor blades, a so-called secondary flow occurs, which forms along the wall from a pressure side of one stator / rotor blade to the suction side of the respectively adjacent stator / rotor blade. By means of this secondary flow, a further secondary flow or a corner separation of the flow caused thereby in a corner is promoted and reinforced. The corner separation takes place on the suction side of the stator / rotor blade in a direction away from the main flow, adjacent to the wall corner.

Therefore, in order to increase the efficiency of a stator / rotor stage, the secondary flow described above, which is ultimately responsible for the reduced corner offset efficiency, must be reduced as much as possible. According to the prior art, for example, EP 0 976 928 A1, this problem is solved by at least one transverse lamella, which is in a flow volume, being attached to at least one wall, which is adjoined by a stator blade at a distance from the suction side of the relevant stator blade extends. For a better understanding of the operation of such a cross-blade, reference is made to the attached Figure 3, in which the schematic section of a stator stage of an axial compressor according to the above-defined prior art is shown.

Accordingly, spaced from the suction side of the stator blade 1 shown, a transverse blade 3 and further transverse blades 3 'are arranged, which extend from the inside of an outer wall 2 into a flow volume 7. The transverse lamella 3 and the further transverse lamellae 3 'are spaced equidistant from each other along an azimuthal direction 8 from the suction side of the stator blade 1 and from one another.

By providing the transverse lamellae 3, 3 ', higher pressure increases along the wall can be allowed in each case without an adverse separation of the flow occurring. This means that at a given pressure build-up a much shorter

This route is sufficient without major losses occur. This makes it possible to construct more compact stator compressor stages. With the cross blades on the inside of the outer wall and / or on the outside of an inner wall (hub) thus the detachment on the side walls and also on the suction side of the blades the Verdichtergitters, in particular thus the abovementioned Eckablösungen significantly reduced.

Although the prior art according to EP 0 976 928 A1 has found a technical solution to the flow problem described above, the design of the flow guide elements defined as cross blades on the inside of the housing wall and / or the hub proves to be technically complicated and expensive.

The present invention is therefore based on the object to implement the functional principle known from the prior art manufacturing technology such that an increase in the cost of the stator / rotor stage as a result of an increased manufacturing effort is omitted.

This object is achieved by a stator and / or rotor stage with the features at least of patent claim 1.

Accordingly, the subject matter of the invention makes use of the production technology generally known from the prior art, for example according to DE 10 312 224 A1, according to which flow-stressed components are produced by milling out the component from a workpiece as a whole. In principle, however, the milling machining in the prior art is carried out in such a way that, as far as possible, no milling grooves or grooves emerge, or the milling grooves caused run in a certain direction with respect to the direction of flow of the component, in order to enable optimized finishing to eliminate the scoring. So far, the purpose of this particular method is that any scoring marks caused in the

Can be smoothed frame of a subsequent fine machining.

According to the invention, however, it is now provided to carry out the milling of the workpiece such that predetermined milling grooves are formed on the inner side of the outer wall or the outer side of the hub, which correspond to the cross-blades known from the prior art or can take over their function. In this way, the at least one transverse lamella can practically in conjunction with the production of the flow-loaded component, in this case the at least one blade a stator and / or rotor stage are produced without an additional manufacturing step is required.

In addition, the milling process for the production of the flow-stressed component and at the same time the at least one transverse lamella can be set such that a refinement known as compulsory from the prior art can be dispensed with. This means that in this case, as it were, a semifinished product, ie a workpiece roughly machined only by milling, in which predefined milling grooves are formed in the form of the transverse lamellae described at the outset, is used as the finished stator and / or rotor stage. As a result, the manufacturing process can be further simplified and thus reduced compared with the production method generally known from the prior art.

Further advantageous embodiments of the invention are the subject of the remaining patent claims.

The invention will be explained below with reference to a preferred embodiment with reference to the accompanying drawings.

1 shows the sectional perspective view of a flow-loaded component, in the present case a blade with adjoining outer wall / hub according to the preferred embodiment of the invention, which is milled in one piece from a single workpiece,

Fig. 2 shows a sectional view of the component along the section line A-A according to FIGS. 1 and

Fig. 3 shows the schematic diagram of a known from the prior art stator with externally arranged cross blades.

According to the appended FIG. 1, the stator and / or rotor stage of an axial compressor of a turbomachine of the preferred exemplary embodiment of the invention generally consists of a plurality of circumferentially uniformly spaced blades 1, which are respectively at their radially outermost and / or or radially innermost end tip with the inside of an outer wall 2 and / or the outside of a hub 4 are preferably integrally connected. The blade 1 and the hub 4 and the outer wall 2 are also preferably made by a milling process of a solid block.

With regard to these milling methods, there are many technical solutions in the art, e.g. the milling method according to the principle of plunge milling, wherein a main feed direction of the cutter extends in the direction of its milling axis. As a result, milling grooves or grooves, which extend approximately perpendicular to the main flow direction of the axial compressor, are formed on the surface of the machined blades. Alternatively, however, there are also such milling method, according to which a cutter is moved relative to the workpiece to be machined so that the thereby adjusting Fräsrillen run approximately parallel to the aerodynamic flow direction of the component in operation. Finally, methods for the production of flow-loaded components in the form of stator or rotor blades of an axial compressor are known, in which the workpiece to be machined is machined with a ball cutter such that the main axis of the ball cutter is perpendicular to the radial extent of the blading to be milled and the resulting milling grooves is performed. In principle, however, all known milling methods for producing a stator and / or rotor blading serve to produce the smallest possible milling grooves, which are additionally reduced by a subsequent fine machining process.

As can now be seen from FIG. 1, according to the principle of one of the above, or another, already generally known from the prior art

Milling process of the milling process preprogrammed such that in the course of Ausarbeit- the blading - in the present case, only one end portion of a single blade shown - on the inside and / or outside of the outer wall 2 and the hub 4 milling grooves 3, 3 ' preferably give predetermined contour and predetermined course. That is, the resulting milling grooves 3, 3 'define lamellar ribs projecting radially into a flow volume of the respective step. The flow volume is defined here as the volume of the space through which a fluid flows during operation of the drive machine. For example, in the prior art according to EP 0 976 928 A1, concrete details regarding the sipe depth, the lamellar spacings in an azimuthal direction 8 and possibly also the lamellar shape are to be taken which are approximated by the milling grooves 3, 3 'worked out in the aforementioned milling process can. It should be noted, however, that the resulting milling grooves 3, 3 'with respect to their cross-sectional shape and with respect to the groove depths and distances in the azimuth direction 8 can also be purely random, which may reduce the self-adjusting effect on the flow behavior, but still a influencing of the gas flow which improves the efficiency of the respective stage can be achieved.

1, the milling grooves 3 shown there run in the flow direction 7 substantially parallel to the suction side of the illustrated blade 1 and at azimuthal distances (height distances) to the suction side of the relevant blade 1 and are beyond the rear tear-off edge 5 extended the relevant blade 1 addition. In addition, they always surround the blade nose 6 following the blade contour and extend along the pressure side of the blade 1 in the direction of the rear blade tear-off edge 5.

2, the milling grooves 3, 3 'in the outer wall 2 and / or the hub 4 on the suction side of the respective blade 1 are preferably more pronounced than the milling grooves 3, 3', which have arisen on the pressure side of the relevant blade 1. Accordingly, a modification of the present embodiment may also provide only the formation of milling grooves 3, 3 'on the suction side of the relevant blade 1, whereas on the pressure side, for example. By a finishing process downstream of the milling process, the Fräsriefen 3, 3' or grooves are largely reduced , Also, the blade 1 can be subjected to a downstream finishing process for reducing the resulting Fräsriefen 3, 3 '.

Decisive in the technical implementation of the subject invention in a machine preferably a milling machine, it is therefore that by targeted application or leave (not etching away) of the Fräsriefen 3, 3 'in the hub or housing area between the blades 1, the cross blades, as they from the mentioned Prior art are known to be mimicked so as to obstruct or even prevent the secondary flow, which leads to an efficiency deterioration of the stator or rotor stage. Thus, the present invention combines an already successfully tested principle of secondary flow control with the technical feasibility in the manufacturing process of Statorbzw. Rotor stage in particular by milling. In principle, however, the subject of the invention can also be used successfully in other components subject to flow, such as, for example, the so-called compressor blisks.

Claims

claims

1. stator and / or rotor stage of an axial compressor of a turbomachine having at least one suction side and a pressure side forming blade (1) at at least one radial end with the inside of an outer wall (2) and / or the outside of a hub ( 4) and with at least one transverse lamella (3, 3 ') which extends, spaced and opposite to the suction side of the blade (1), from the corresponding outer wall (2) and / or the hub (4) into a flow volume characterized in that the transverse lamella (3, 3 ') is formed integrally with the outer wall (2) and / or the hub (4) preferably by milling.

2. Stator and / or rotor stage according to claim 1, characterized in that the at least one transverse lamella (3, 3 ') follows the surface contour of the blade suction side in a main flow direction (7) of the axial compressor, preferably at a parallel distance.

3. stator and / or rotor stage according to claim 2, characterized in that the at least one transverse lamella (3, 3 ') to the blade nose (6) around to

Vane pressure side is extended and the surface contour follows in the direction of Schaufelabrisskante (5).

4. stator and / or rotor stage according to one of claims 1 to 3, character- ized in that the at least one transverse lamella (3, 3 ') in the main flow direction (7) beyond the rear Schaufelabrisskante (5) is extended.

5. stator and / or rotor stage according to one of claims 1 to 4, characterized in that the at least one transverse lamella (3, 3 ') is formed by at least one ne milling groove, which in the manufacture of the blade profile through

Milling has arisen.

6. stator and / or rotor stage according to one of the preceding claims, characterized in that the at least one transverse lamella (3, 3 ') has a predetermined cross-sectional shape and / or a predetermined louver depth.

7. A method for producing a stator and / or rotor stage according to claim 1, according to which the at least one blade (1) is preferably milled out of a workpiece by a machining method, such that the at least one blade (1) and the outer wall (2) and / or hub (4) connected thereto are made in one piece from a single piece

Form component, characterized in that the at least one transverse lamella (3, 3 ') is a milling groove, which in the manufacture of the blade profile (1) by chip removal on the inside of the outer wall (2) and / or the outside of the hub (4) is trained.

8. Use of a method by a machining method, preferably milling method according to claim 7 semi-finished product as a stator and / or rotor stage according to claim 1.