WO2004030430A1

WO2004030430A1 - Hydraulic machine rotor

Info

Publication number: WO2004030430A1
Application number: PCT/EP2003/009989
Authority: WO
Inventors: Helmut Keck
Original assignee: Va Tech Hydro Gmbh & Co
Priority date: 2002-09-26
Filing date: 2003-09-09
Publication date: 2004-04-15
Also published as: EP1543240A1; ATA14462002A; AR041277A1; AT412495B; AU2003266365A1

Abstract

The blades (2) of a hydraulic machine rotor (1) are formed in such a way that it is possible to obtain greater efficiency and enable the hydraulic machine to be operated even in partial load ranges without incurring any significant limitations. The aim of the invention is to obtain a hydraulic machine exhibiting good cavitational behavior and to produce and mount a rotor (1) in a manner which is as simple as possible without any limitations, using very small clearances and processing machines. In order to achieve said objectives, the rotor blades (2) of the inventive rotor (1) are divided such that part (2a) of the rotor blades (2) can detached from the rotor (1).

Description

Impeller of a hydraulic machine

The subject application relates to an impeller of a hydraulic machine, preferably of the positive pressure type, such as a Francis turbine, Francis pump turbine or radial or diagonal pump, with a number of impeller blades, at least one impeller blade being divided and at least two impeller blade parts being arranged detachably from one another, and a method for producing such an impeller.

An impeller of a hydraulic machine, e.g. a Francis turbine or pump turbine has a plurality of impeller blades, two blades each having a flow channel for an operating medium, e.g. Form water through which the operating medium flows during operation of the hydraulic machine and thus sets the rotor in rotation. The manufacture of such a rotor is very complex due to the complex geometric shapes of the impeller blades. In order to manufacture the rotor, e.g. by welding, etc., and / or a corresponding processing of the surfaces, e.g. by grinding, polishing, etc., using processing machines, such as To enable robots, etc., the impeller blades must not be too close together. In addition, there is always the danger in nearby bucket regions that debris gets stuck in the impeller and thus impairs operation, or even makes it necessary to switch off the hydraulic machine. On the other hand, in the area of the trailing edge (= leading edge for a pump turbine in pump mode) of the impeller blades, a small radius on the inner cover plate is desirable, since this is advantageous for operation, especially at operating points away from the design operating point. With a small radius, for example, the vortex formation at the outlet of the impeller would improve significantly in part-load ranges. Many impellers also have an impeller hood in order to be able to continue the flow in a controlled manner after exiting the impeller blade, which would however make mounting the impeller on the shaft more difficult or even impossible with such small radii. At the impeller outlet, a high number of blades and small diameters lead to very tight spaces. A small number of blades, on the other hand, leads to large distances at the impeller inlet and a high load and cavitation at the impeller inlet.

In order to eliminate this fundamental contradiction, impellers were manufactured, for example, in such a way that every second or third blade in the entire outlet area of the impeller blades was made shorter than the neighboring impeller blades, so-called "splitter blade runner", and the impeller blades in the entry area were all left the same The advantage of this design is that there is more space in the exit area was created, which essentially eliminated the above disadvantages. However, this increases the risk of cavitation in the area of the outer cover plate between the center of the blade and the trailing edge, since there the blade loads increase due to the partially reduced blade lengths.

A rotor of a Francis turbine is known from US Pat. No. 6,135,716, in which the cavitation behavior has been improved in that the inlet and outlet edges of the impeller blades are specially shaped with respect to the axis of rotation of the turbine. The lengths of all impeller blades are left the same, which corresponds to a conventional impeller. However, this again results in the disadvantages mentioned above with regard to production and operation apart from the design.

DE 19803 390 C1 shows an impeller that consists of several individual impellers in order to obtain a particularly adaptable impeller that achieves the highest possible efficiency for a very wide range of operating conditions. However, such an impeller requires a very high level of production.

The manufacture of impellers can be simplified under certain circumstances by assembling the impeller and / or the impeller blades from several individual parts. Examples of this can be found in DE 1944 360 A or US 6, 155,783 A.

In all of these variants, however, the problem of fastening or assembling the impeller in the case of impellers with impeller blades which are brought very close to the axis of rotation of the hydraulic machine, which improves the operation of the hydraulic machine in part-load ranges, remains.

It is therefore an object of the present application to provide an impeller of a hydraulic machine which, even with very small impeller blade diameters in the area of the inner cover plate, enables the impeller to be easily assembled.

This object is achieved by the present invention in that at least part of the impeller blade is arranged on an impeller hood that can be detached from the impeller. By dividing the impeller blade, it is now possible to separate part of the impeller blade from the rest of the impeller and thus to make the connection between the impeller and shaft accessible. However, very small impeller blade diameters can also be realized with this without restrictions.

The impeller hood is particularly well suited for receiving at least a part of the impeller blades, since this is usually designed to be detachable from the impeller in order to facilitate assembly. In addition, the impeller hood is a more compact and easy-to-use component than the rest of the impeller, so that the impeller can be installed with the divided impeller blades can be easily accomplished.

For this purpose, it is also favorable to connect the impeller hood directly to the connecting means

To connect the impeller hub detachably, which also facilitates assembly.

A particularly easy to manufacture impeller is obtained if the impeller blade is made in two parts. This makes it easy to assemble the impeller.

In order to improve the operating behavior of a divided impeller blade, it is favorable to connect the individual parts of the impeller blade to one another. As a result, the vibration behavior of the impeller blade can be significantly improved by increasing the stability.

A particularly advantageous impeller is obtained if a contact point between the inner cover plate and the leading edge and / or a contact point between the inner cover plate and the trailing edge of at least one first impeller blade has a larger radius with respect to the axis of rotation of the hydraulic machine than the corresponding contact points of an immediately adjacent second impeller blade, wherein the contact points between the outer cover plate and the leading and trailing edge of the first and second impeller blades have essentially the same radius.

On the one hand, this makes it possible to achieve very small radii in the outlet area of the impeller on the inner cover plate, without causing production problems or problems due to an excessively narrow blade arrangement. On the other hand, the load in the areas of high blade load, i.e. in the area of contact of the blade with the outer cover plate, is not increased or only increased insignificantly, since the contact lengths in these areas are not changed compared to conventional impellers, so that there is no deterioration in cavitation in the Operation results.

Hydraulically and in terms of production technology, it is advantageous if the leading and trailing edges of a first and second impeller blade of the rotor are shaped at least in sections, the edges preferably being shaped identically between the contact point on the outer cover plate and any point on the leading or trailing edge are.

In order to operate the hydraulic machine smoothly even in partial load ranges, the ratio between the smallest radius of a contact point of the trailing edge with the inner cover plate of a blade and the radius of the contact point of the trailing edge with the outer cover plate of this blade is preferably less than or equal to 0.4 less than or equal to 0.2. This means that the exit vortex from the impeller is reduced and the hydraulic machine can be operated perfectly even in partial load ranges.

The number of impeller blades of the impeller is advantageously chosen to be divisible by two or three, with every second or third impeller blade then having different leading and / or trailing edges, which results in major manufacturing advantages, at least in the area of small radii, since the individual impeller blades can be machined without any problems are.

For hydraulic reasons, it is favorable to place the contact point between the trailing edge and the inner cover plate of at least one blade axially below the center of the leading edge of this blade and, with respect to the direction of rotation of the impeller, the contact points of the leading and trailing edge with the outer cover plate of at least one blade in front of the corresponding one Arrange contact points of the leading and trailing edge with the inner cover plate of this blade. Additional improvements in the hydraulic behavior of the machine result if, with respect to the axis of rotation of the impeller, the radial distance between the contact points of the trailing edge with the outer and inner cover plate is at least one blade greater than the radial distance between the contact points of the entry edge with the outer and inner cover plate Blade is advantageously greater than 10 °, preferably greater than 15 °. Among other things, this can further improve the cavitation behavior of the hydraulic machine.

The present invention will now be described with reference to the following schematic, non-limiting figures 1 to 4, wherein the

1 shows an impeller according to the invention,

2 shows an impeller blade of a conventional impeller of a hydraulic machine, FIG. 3 impeller blades of a hydraulic machine with different inputs and

Trailing edges and Fig. 4 is a view in the axial direction of an impeller blade

shows.

An impeller 1 of a positive pressure turbine, such as a Francis turbine or pump turbine, is generally connected to the shaft 7 via an impeller hub 9 by means of a suitable fastening means 8, here, for example, a screw connection, as shown in FIG. 1, so that the rotary movement of the impeller 1 is transmitted to the shaft 7, or vice versa in a pump turbine in pump mode. The impeller 1 also has an inner 3 and an outer cover disk 6, between which the impeller blades 2 are at least partially are arranged. The impeller blades 2 can be attached to the cover disks 3, 6 by any method, in practice often by welding, but could also be cast as one part.

In the extension of the impeller hub 9 there is an impeller hood 10 to which a part of the impeller blade 2a is fastened, e.g. again by welding. Likewise, the impeller hood 10 could be cast as one part with the impeller blade part 2a. The impeller blade 2 is thus divided into two parts, the two parts being detachable from one another. For this purpose, a connecting means 11 is provided, here e.g. Countersunk screws with which the impeller hub 9 can be detachably connected to the impeller hood 10. This makes it possible to remove part of the impeller blade 2a with the impeller hood 10 from the rest of the impeller, so that the accessibility in the axial region of the impeller 1, e.g. for impeller attachment 8, is improved. Of course, any other connection between the impeller hood 10 or impeller 1 and impeller hub 9 would also be conceivable. The view Y of FIG. 1 shows the impeller hood 10 in an axial view, in this example all the impeller blades 2 being of split design, which, as will be described further below, does not necessarily have to be the case. The section X - X through the connecting line of the impeller blade parts of Fig. 1 shows that the individual parts by a suitable connecting means 12, such as here e.g. Countersunk screws can also be connected to one another along the connecting line, which improves the operating behavior of the impeller blades 2, especially with regard to vibration behavior and stability.

Of course, any other suitable connecting means could also be used instead of countersunk screws 11, 12.

A conventional impeller blade 2 of a hydraulic machine according to FIG. 2 is arranged between an inner 3 and outer cover plate 6 and has an inlet edge 4 and an outlet edge 5, which are the inner 3 and outer at the four contact points A, B, C and D. Cut cover plate 6.

Adjacent impeller blades 1 form a flow channel through which the operating medium, for example water, can flow. For a hydraulic machine, there would be a flow from the leading edge 4, for example from a well-known spiral housing (not shown here) and a diffuser, to the trailing edge 5 and further to a well-known suction pipe (also not shown here) which opens into an underwater. For a pump or pump turbine in pump mode, the direction of flow would be reversed accordingly, here from the leading edge 5 to the leading edge 3. The flow of the operating medium causes the impeller 1 to rotate (in the case of a turbine) or the rotation of the impeller 1 operating medium is promoted (at a pump turbine in pump mode). The axis of rotation of the turbine is indicated by the dash-dotted line.

The impeller blade 1 is in most cases not flat, but can in principle have any spatial curvature, as indicated in FIG. 4, in which a view of an impeller blade 2 is shown in the axial direction of the axis of rotation. It can be seen that the contact points C (or G), D of the leading edge 4 (or 4a) on the inner cover plate 3 and on the outer cover plate 6 can have a circumferential distance φ _E with respect to the axis of rotation of the turbine, that is to say based on the axial direction of the axis of rotation does not come to lie on a radial line through the axis of rotation, but are arranged at a certain angle to one another. The same can of course also apply to the contact points B (or F), A of the trailing edge 5 (or 5a) on the inner 3 and outer cover plate 6, where a circumferential distance φ _A can be provided. It is favorable for the cavitation behavior of the turbine if this circumferential distance φ _{A of} the contact points B (or F), A of the trailing edge 5 (or 5a) is greater than the radial distance φ _{E of} the contact points C (or G), D the leading edge 4 (or 4a) is selected. A preferred value for φ _A is 15 ° or greater.

In addition, it can be seen in FIG. 4 that the contact points D, A on the outer cover plate 6, viewed in the direction of rotation, are arranged in front of the corresponding contact points B (or F), C (or G) on the inner cover plate.

In Fig. 3, an impeller 1 is now shown schematically, the impeller blades 1 of which are again arranged between an inner 3 and outer cover plate 6 and again form a flow channel for the operating medium.

With this impeller 1, however, the leading edge 4 and the trailing edge 5 of every second or third impeller blade 2 are partially pulled outwards (or pulled inwards, depending on the point of view) with respect to the axis of rotation of the turbine. Ie, that part of the impeller blades 2 are still limited conventionally, as described in FIG. 1, that is, by an entry edge 4 between the contact points C and D, an exit edge 5 between the contact points A and B, and the inner 3 and outer cover plate 6. Every second or third impeller blade 2 deviates from this limitation. The leading edge 4 of two adjacent impeller blades 2, 2 'extends from the contact point D between the leading edge 4 and the outer cover plate 6 to any point H on the leading edge 4, from this point H the leading edge 4a is pulled outwards with respect to the axis of rotation, ie that the contact point G of the leading edge 4a of the impeller blade 2 on the inner cover plate 3 has a larger radius than the corresponding contact point C of the adjacent impeller blade 2 '. At the exit edge 5, the above applies analogously. The trailing edges 5 of the immediately adjacent impeller blades 2, 2 'essentially coincide between a contact point A on the outer cover plate 6 and any point E on the trailing edge 5. Starting from this point E, the trailing edge 5a is behind every second or third impeller blade 2 pulled outside (or pulled in, depending on the point of view), ie that the contact point B of the trailing edge 5a of the impeller blade 2 on the inner cover plate 3 has a larger radius than the corresponding contact point F of the adjacent impeller blade 2 '.

The delimitation of a part of the impeller blades 2 thus runs between the contact points C and D, which form the leading edge 4, and the contact points A and B, which form the trailing edge 5, as in conventional blades, and the delimitation of every second or third impeller blade 2 'runs between the points D, H and G which form the leading edge 4a and the points A, E and F which form the trailing edge 5a.

The above description is of course only exemplary. It would of course also be conceivable to pull only the leading edge 4 or only the trailing edge 5 or leading edge 4 and trailing edge 5 outwards in sections.

The points E and H can moreover be arranged at any position on the leading edge 5 or leading edge 4, in particular these points E and H could also coincide with the contact points A and D on the outer cover plate 6 in an embodiment according to the invention.

By means of these alternatingly differing outlet edges 5, 5a, the impeller blades 2, 2 'can be brought very close to the axis of rotation of the turbine, ie the contact points F of the outlet edges 5 on the inner cover plate 3 can have very small diameters. In particular, a radius ratio r _F / r _A at the trailing edge 5 of less than or equal to 0.2 can be achieved, which was previously problematic, if at all possible.

If the trailing edge 5 is brought very close to the axis of rotation in the area of the inner cover disk 3, space problems may arise with the attachment of the impeller 1 to the shaft 7. In order to solve this problem, one could, for example, as already described for FIG. 1, at least split the impeller blades 2 ', which come close to the axis of rotation, and arrange the impeller blade part, which is marked by the points E, F, B, on the impeller hood 10. The impeller blade 2 could of course also be divided at any other desired location, which would not change the inventive character. Only after assembly of the impeller 1 would the impeller blades 2 be completely formed. To make assembly easier, it would also be conceivable to hood 10 and / or 9 centering aids, such as a groove and a wedge or the like, to be provided on the impeller hub.

For example, if only every other impeller blade 2, as described above, were extended in the direction of the axis of rotation, e.g. around the impeller blade part between the points E, F and B, it could also be sufficient to divide only this extended impeller blade 2, as a result of which the impeller hood 10 could be manufactured more easily.

Claims

claims

1. Impeller of a hydraulic machine, preferably of the positive pressure type, e.g. a Francis turbine, Francis pump turbine or radial or diagonal pump, with a number of impeller blades (2), at least one impeller blade (2) being divided and at least two impeller blade parts (2, 2a) being arranged detachably from one another, characterized that at least a part (2a) of the impeller blade is arranged on an impeller hood (10) detachable from the impeller (1).

2. Impeller according to claim 1, characterized in that the impeller blade (2) is made in two parts.

3. Impeller according to claim 1 or 2, characterized in that a connecting means (11) is provided with which the impeller hood (10) can be releasably connected to an impeller hub (9).

4. Impeller according to one of claims 1 to 3, characterized in that a connecting means (12) is provided with which at least two parts of the impeller blade (2, 2a), preferably releasably, can be connected to one another.

5. Impeller according to one of claims 1 to 3, characterized in that a contact point (G) between an inner cover plate (3) and an entry edge (4a) and / or a contact point (B) between the inner cover plate (3) and an exit edge (5a) at least one first impeller blade (2) has a larger radius with respect to the axis of rotation of the hydraulic machine than the corresponding contact points (F, C) of an immediately adjacent second impeller blade (2 '), the contact points (A, D) between the outer cover plate (6) and the leading and trailing edges (4, 5) of the first and second impeller blades (2, 2 ') have essentially the same radius.

6. Impeller according to claim 5, characterized in that the leading edges (4, 4a) of the first and second impeller blades (2, 2 ') of the impeller (1) are shaped differently at least in sections.

7. impeller according to claim 6, characterized in that the leading edges (4, 4a) of the first and second impeller blades (2, 2 ') of the impeller (1) between the contact point (D) of the leading edge (4, 4a) on the outer Cover plate (6) and a predeterminable point (H) on the leading edge (4, 4a) are formed substantially in the same way.

8. impeller according to one of claims 5 to 7, characterized in that the trailing edges (5, 5a) of the first and second impeller blades (2, 2 ') of the impeller (1) are shaped differently at least in sections.

9. impeller according to claim 8, characterized in that the trailing edges (5, 5a) of the first and second impeller blades (2, 2 ') of the impeller (1) between the contact point (A) of the trailing edge (5, 5a) on the outer Cover disc (6) and a predeterminable point (E) on the trailing edge (5, 5a) are shaped essentially in the same way.

_**

10. Impeller according to one of claims 5 to 9, characterized in that the ratio between the smallest radius r _{F of} a contact point (F) of the trailing edge (5) with the inner cover plate (3) of an impeller blade (2, 2 ') and Radius r _A des

Contact point (A) of the trailing edge (5) with the outer cover plate (6) of this impeller blade (2, 2 ') is less than or equal to 0.4, preferably less than or equal to 0.2.

11. Impeller according to one of claims 5 to 10, characterized in that the number of impeller blades (2, 2 ') of the impeller (1) is divisible by two or three.

12. Impeller according to claim 11, characterized in that in the case of a divisible number of impeller blades (2, 2 ') the trailing edge (5) and / or the leading edge (4) of every second impeller blade (2') has a contact point (F) on the inner cover plate (3) with a smaller radius than the corresponding contact point (B) of the adjacent impeller blade (2) with respect to the axis of rotation of the impeller (1).

13. impeller according to claim 11, characterized in that in a divisible by three number of impeller blades (2, 2 ') the trailing edge (5) and / or the leading edge (4) of a third of the impeller blades (2, 2') a contact point (F) on the inner cover plate (3) with a smaller radius with respect to the axis of rotation of the impeller (1) than the corresponding contact points (B) of the adjacent impeller blades (2).

14. Impeller according to one of claims 5 to 13, characterized in that a contact point (F, B) between the trailing edge (5, 5a) and the inner cover plate (3) of at least one impeller blade (2, 2 ') in the axial direction below the center the leading edge (4, 4a) of this impeller blade (2, 2 ') is arranged.

15. Impeller according to one of claims 5 to 14, characterized in that with respect to the direction of rotation of the impeller (1) the contact points (A, D) of the input and

Trailing edge (4, 4a, 5, 5a) on the outer cover plate (6) of at least one impeller blade (2, 2 ') in front of the corresponding contact points (B, C, F, G) of the entry and exit edge (4, 4a, 5, 5a) on the inner cover plate (3) of this impeller blade (2, 2 ') are arranged.

16. Impeller according to one of claims 5 to 15, characterized in that with respect to the axis of rotation of the impeller (1) the circumferential distance Φ _A between the contact points (A, B, F) of the trailing edge (5, 5a) on the outer (6 ) and inner cover plate (3) of at least one impeller blade (2, 2 ') greater than the circumferential distance Φ _E between the contact points (D, C, G) of the leading edge (4, 4a) on the outer (6) and inner cover plate ( 3) this impeller blade (2, 2 ').

17. Impeller according to claim 16, characterized in that the circumferential distance Φ _A between the contact points (A, B, F) of the trailing edge (5, 5a) on the outer (6) and inner cover plate (3) of at least one impeller blade (2 , 2 ') is greater than 10 °, preferably greater than 15 °.

18. Method for producing an impeller (1) of a hydraulic machine, preferably of the positive pressure type, such as e.g. a Francis turbine, Francis pump turbine or radial or diagonal pump, with a number of impeller blades (2), characterized in that at least one part (2a) of at least one impeller blade (2) is attached to an impeller hood (10), at least a further part of this impeller blade (2) is fastened to an impeller hub (9) and the impeller hood (10) is then connected, preferably detachably, to the impeller hub (9), so that the individual impeller blade parts have a substantially continuous impeller blade (2) form.

19. The method according to claim 18, characterized in that the individual impeller blade parts, preferably releasably, are connected to one another.

20. The method according to claim 18 or 19, characterized in that the impeller blade parts are manufactured in advance as individual parts and then welded to the impeller hood (10) or impeller hub (9).

21. The method according to claim 18 or 19, characterized in that the individual impeller blade parts with the impeller hood (10) or impeller hub (9) are cast as one part and, if appropriate, subsequently with a surface treatment method, such as, e.g. Grinding or polishing.