EP2304189B1 - Rotor blade and turbomachine comprising a rotor blade - Google Patents

Description

The present invention relates to a blade for a turbomachine, in particular a steam turbine, with a plug foot with a plurality of lobes having radially outer first sections and radially inner second sections whose axial extent are smaller than that of the outer sections, and a turbomachine, in particular a Steam turbine, with such blades.

In addition to fixedly connected to the rotor of the turbomachine, for example, welded blades are today, especially in steam turbines blades with Christmas tree feet and feet commonly used. Thus, Dubbel, paperback for mechanical engineering, in its 20th edition on page R 67 shows a blade for a steam turbine with a three-lobated plug foot, the individual lobes on their two axial sides a paragraph such that the lobes a radially outer first section and have a radially inner second portion whose axial extension is less than that of the outer first portion.

From the EP 1 862 642 A2 and the GB 355 759 A are also blade for a steam turbine with a dreilappigen plug disclosed.

Such plug feet must endure high stresses during operation. On the one hand occur, especially at higher rotor speeds, large centrifugal forces acting in the radial direction. In addition, the fluid flowing around the blades and deflected therethrough, such as the work-carrying steam that is expanded in a steam turbine, exerts forces in the axial and circumferential directions on the rotor blades that must be supported in the plug feet.

Object of the present invention is to improve the attachment of blades of turbomachines by means of plug-in foot.

To solve this problem, a blade according to the preamble of claim 1 is further developed by its characterizing features. Claim 10 represents a turbomachine with one or more such blades un protection. The subclaims relate to advantageous developments of the present invention.

The plug-in foot of a rotor blade according to the invention has a first lobe and two second lobes arranged in the axial direction on both sides of this first lobe. The plug-in foot can in particular be formed in three-lobed form, the first tab then forming a central tab and the two second tabs forming edge tabs. However, it can also be provided on one or both axial sides of a first or second flap further tabs, which are then preferably formed in their essential geometric dimensions as the first or a second lobe.

According to the invention, the mutually facing axial sides of the first and second lobes have a shoulder which extends in the axial direction in such a way that the lobes have a radially outer first section and a radially inner second section connected thereto via the shoulder whose extension is in the axial direction Direction is less than that of the first, outer section. The mutually remote axial sides of the second lobes preferably have no shoulder, but form continuous, preferably flat axial end surfaces. In the case of a three-lobed plug-in foot, the central tab therefore has a shoulder on both its axial sides, the two edge tabs only on their inner axial sides facing the central tab.

The present invention is based on the finding that by suitable choice of the radial heights of the first and second sections in relation to an overall axial width of the plug-in foot, the forces that such a plug foot can absorb can be significantly increased.

In this case, the distance between the axially outer end faces of the two second lobes is referred to as the overall axial width. If these two axial end faces are not parallel, the axial overall width can be based, in particular, on a minimum, maximum or average distance in the axial direction. The directions "axial", "radial" and "in the circumferential direction" refer in the present case to the directional information for rotors in turbomachines, when the blade according to the invention is attached to such a rotor.

According to the invention, it is proposed that the ratio of the radial height of the first, radially outer portion is in the range between 0.39 and 0.45, preferably between 0.40 and 0.44, while the ratio of the radial height of the second, radially inner portion to the total axial width between 0.40 and 0.46, preferably between 0.41 and 0.45. The radial height of a first, radially outer portion is in particular the radial extent between the shoulder and a web referred to, which connects a first and a second flap in the axial direction with each other. Accordingly, the radial extent of a second, radially inner portion is referred to in particular as the radial extent between the shoulder and a radially inner end face of the tab. Varies thereby a radial extent in the axial direction, since, for example, a radial end, the heel and / or a two adjacent lobes connecting web extending in the axial direction is not parallel to the axial direction, as a radial height in particular a minimum, maximum or average radial extent be based on.

Preferably, a ratio of a total radial height of the lobes to the total axial width is in the range between 0.88 and 0.94, preferably between 0.89 and 0.93. The total radial height is in particular the sum of the above-defined radial heights of the first and second sections plus a radial height of the shoulder. This shoulder may be a purely radial step, so that the axial extent of a flap between the first and second area changes abruptly or in a very short radial section, i. e. the shoulder has a radial height substantially equal to zero. In this case, the total radial height may correspond to the sum of the radial heights of the first and second sections. However, the shoulder can also have a slope, so that the axial width of the flap tapers linearly between the first and second sections. Other, in particular convex or concave curved paragraphs are possible.

Corresponding to the above-mentioned preferred ranges of the radial heights of the first and second sections and the total radial height relative to the overall axial width, a preferred ratio results for a shoulder from radial height to overall axial width in the range between 0.00 and 0.14, preferably between 0.00 and 0.12.

The first, radially outer or second radially inner portion of a first lobe has, based on the total axial width, preferably a ratio in the range between 0.21 to 0.27, preferably between 0.22 and 0.26 or between 0, 11 and 0.17, preferably between 0.12 and 0.16. The axial extensions of the first or second section of a second lobe are preferably in the ratio of 0.16 to 0.22, preferably between 0.17 and 0.21 or in a ratio between 0.11 and 0 for the total axial width, 17, preferably between 0.12 and 0.16.

Preferably, the two axial sides of a tab are formed parallel to each other. If this is not the case, the axial extension can be based, in particular, on a minimum, maximum or average distance between the two axial sides.

For fastening the plug foot in a groove arrangement of the rotor of the turbomachine provided for this purpose, the first and the second tabs preferably have one, preferably two or more radially spaced bores which are aligned with each other, so that in each case one, preferably conical, bolt can be driven into it , To avoid manufacturing and assembly tolerances these holes can be drilled and / or rubbed even after inserting the feet in the Nutanordnungen.

Preferably, the position of the bolt is chosen such that the centrifugal force in an upper crack cross section of the Bolzenebene causes little or no bending loads. Preferably, the midpoint of a radially outer bore has a radial distance from the radially outer end of the first portion, for example, the radially inner end of a first and second lobe connecting web, the ratio in the range of 0.24 and 0 with the total axial width , 30, preferably between 0.25 and 0.29, while the center of a radially inner bore has a corresponding ratio in the range between 0.60 and 0.66, preferably between 0.61 and 0.65.

As explained above, the first and second flaps are preferably connected to each other via a radially outer web in which the first portions of the flaps terminate radially. First tab, second tab and / or web can thereby integrally formed, in particular ur- and / or non-cutting or machined formed, or formed in several pieces and connected to each other, for example, welded, be. The radially outer web preferably has a radial height whose ratio to the total axial width is in the range between 0.12 and 0.18, preferably between 0.13 and 0.17.

Preferably, when the blade is mounted in the direction of rotation of the rotor, an axial front face of a second flap is arranged parallel to the radial plane of the holes, so that the axial axial end face of the plug foot is correspondingly rotated by one blade pitch.

The web on which the blade profile is arranged on the side opposite the plug-in foot, preferably lies in a plane which is essentially perpendicular to this radial plane through the bores. For this purpose, a radially inner and / or outer end face of the web substantially perpendicular to the radial plane of the bores, i. e. be formed in the radial direction through the two centers of the holes extending plane.

A turbomachine according to the present invention has for securing each blade according to the invention a corresponding groove arrangement with a first groove for receiving the first lobe and two second grooves for receiving the second lobe, which are separated from the first groove by a respective web.

Preferably, the grooves are formed substantially complementary to the tab to be absorbed by them, so that reference is made in this regard to the above statements. In particular, the axial total width between axial sides of the two second grooves facing away from one another preferably corresponds essentially to the overall axial width between axial sides of the two second tabs facing away from one another.

In particular, to compensate for manufacturing and / or assembly tolerances while minor differences may be advantageous. As radial heights or axial extensions can, as explained above to the lobes, accordingly maximum, minimum or average distances in the radial or axial direction between parallel or non-parallel surfaces are used.

For example, the ratio of the radial height of the first, radially outer web portion or a first, radially outer groove portion to the total axial width is preferably in a range between 0.40 and 0.46, preferably between 0.41 and 0.45, while the corresponding ratio of the radial height of the second, radially inner web portion or a corresponding radially inner groove portion to the overall axial width preferably between 0.44 and 0.50, preferably between 0.45 and 0.49.

Fig. 1:

eine Laufschaufel nach einer Ausführung der vorliegenden Erfindung in perspektivischer Gesamtansicht;

Fig. 2:

den Steckfuß der Laufschaufel nach Fig. 1 in Draufsicht in Umfangsrichtung;

Fig. 3:

eine Nutanordnung zur Aufnahme des Steckfußes nach Fig. 2 in Fig. 2 entsprechender Ansicht;

Fig. 4:

den in der Nutanordnung nach Fig. 3 aufgenommenen Steckfuß nach Fig. 2; und

Fig. 5:

den Steckfuß nach Fig. 4 in der Draufsicht in axialer Richtung.

Further advantages and features emerge from the subclaims and the exemplary embodiment. This shows, partially schematized:

Fig. 1:

a blade according to an embodiment of the present invention in an overall perspective view;

Fig. 2:

the blade of the blade after Fig. 1 in plan view in the circumferential direction;

3:

a groove arrangement for receiving the plug-in foot Fig. 2 in Fig. 2 corresponding view;

4:

in the groove arrangement according to Fig. 3 recessed plug-in foot Fig. 2 ; and

Fig. 5:

the plug-in foot Fig. 4 in plan view in the axial direction.

Fig. 1 shows a blade 1 with a three-lobated Steckfuß 2 according to an embodiment of the present invention in a perspective view. As in particular in Fig. 2 to recognize that a plan view of the plug-in foot 2 in the circumferential direction of a rotor of a steam turbine (not shown), in which the plug-in foot 2 can be inserted in the radial direction from the outside, the dreilappige Steckfuß a first central lobe 3 and two in the axial direction a on both sides this central lobe 3 arranged second edge tabs 4. The mutually facing inner axial sides 3.i of the central lobe 3 and 4.i of the edge tabs 4 each have an oblique shoulder 5, while the axially outer end faces of the two edge tabs are planar and parallel to each other. Between a web 7, with the central and peripheral tabs 3, 4 are integrally formed, and the oblique paragraph 5, the central lobe 3 has a first section 3.1 with an axial extent b _F2 and the two edge tabs 4 each have a first section 4.1 with an axial extent b _F1 . These first sections have, measured from the radially inner end face (bottom in Fig. 2 ) of the web 7 to the paragraph 5, ie, up to the point at which the axial extent decreases, a radial height h _F1 . The web 7 has a radial height h _P between the radially outer end of the tabs 3, 4 and an opposite radially outer end side.

Central and peripheral tabs 3, 4 each have one, separated by the paragraph 5 from the first section, second section 3.2 and 4.2, an axial extent b _F3 and a radial height h _F2 between a radially inner end face of the tabs and Approach 5, ie the area in which the axial extent changes.

The mutually facing, inner axial sides 3.i, 4.i of the tabs 3, 4 are formed with the exception of the oblique paragraph 5 parallel to the flat, Absatzsatzaxialaxial end faces 4.a of the two Randlappen.

The plug-in foot 2 has an axial width b between the two axial end faces 4.a of the two edge tabs 4 in the axial direction a. Based on this total axial width b is a total radial height h of the plug foot, which extends between the radially inner end face of the web 7 and the radially inner end faces of the tabs 3, 4, in the ratio: $$\mathrm{H}/\mathrm{b}=\mathrm{0}.\mathrm{91st}$$

$${\mathrm{h}}_{\mathrm{F}\mathrm{2}}/\mathrm{b}=\mathrm{0},\mathrm{43.}$$

The ratios of the above-defined radial heights of the first and second lobes are uniform: $${\mathrm{H}}_{\mathrm{F}\mathrm{1}}/\mathrm{b}=\mathrm{0}.\mathrm{42}\mathrm{respectively}\mathrm{,}$$

$${\mathrm{H}}_{\mathrm{F}\mathrm{2}}/\mathrm{b}=\mathrm{0}.\mathrm{43rd}$$

$${\mathrm{b}}_{\mathrm{F}\mathrm{3}}/\mathrm{b}=\mathrm{0},\mathrm{14}$$

und für die Randlappen 4: $${\mathrm{b}}_{\mathrm{F}\mathrm{1}}/\mathrm{b}=\mathrm{0},\mathrm{19}$$

und wie beim Zentrallappen $${\mathrm{b}}_{\mathrm{F}3}/\mathrm{b}=\mathrm{0},\mathrm{14.}$$

The axial extensions amount
for the central lobe 3: $${\mathrm{b}}_{\mathrm{F}\mathrm{2}}/\mathrm{b}=\mathrm{0}.\mathrm{24}\mathrm{and}$$

$${\mathrm{<figure-callout\; id="3"\; label="b\; F"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">b\; </figure-callout>}}_{\mathrm{F}}/\mathrm{b}=\mathrm{0}.\mathrm{14}$$

and for the marginal lobes 4: $${\mathrm{b}}_{\mathrm{F}\mathrm{1}}/\mathrm{b}=\mathrm{0}.\mathrm{19}$$

and like the central lobe $${\mathrm{b}}_{\mathrm{F}}$$$${\mathrm{}3}_{}/\mathrm{b}=\mathrm{0}.\mathrm{14th}$$

To accommodate this plug foot 2 is in the rotor of the steam turbine in Fig. 3 groove arrangement shown formed with a central groove 30 for receiving the central lobe 3 and two edge grooves 40 for receiving the edge tabs 4.

$${\mathrm{b}}_{\mathrm{N}\mathrm{2}}/\mathrm{b}=\mathrm{0},\mathrm{29},$$

$${\mathrm{t}}_{\mathrm{N}\mathrm{1}}/\mathrm{b}=\mathrm{0},\mathrm{43}$$

und $${\mathrm{t}}_{\mathrm{N}\mathrm{2}}/\mathrm{b}=\mathrm{0},\mathrm{47.}$$

As in particular from the assembly diagram Fig. 4 recognizable, the tabs 3, 4 and the grooves 30, 40 are formed substantially complementary to each other. For this purpose, the groove arrangement has two identical webs 80, which, starting from a radially inwardly lying groove base, each have a second section 82 with an axial extent b _N2 , which merges into an oblique shoulder 50 in a first section with an axial extent b _N1 , Based on the total axial width b between the flat, parallel outer axial sides of the two peripheral grooves 40, which corresponds to the total axial width b between the two axial end faces 4.a of the edge tabs 4, the radial heights t _N1 , t _N2 and the axial extensions b _N1 . b _{N2 of} this first and second section: $${\mathrm{b}}_{\mathrm{N}\mathrm{1}}/\mathrm{b}=\mathrm{0}.\mathrm{19}.$$

$${\mathrm{b}}_{\mathrm{N}\mathrm{2}}/\mathrm{b}=\mathrm{0}.\mathrm{29}.$$

$${\mathrm{t}}_{\mathrm{N}\mathrm{1}}/\mathrm{b}=\mathrm{0}.\mathrm{43}$$

and $${\mathrm{t}}_{\mathrm{N}\mathrm{2}}/\mathrm{b}=\mathrm{0}.\mathrm{47th}$$

The total radial height t, which is the sum of the radial heights t _N1 ; t _{N2 of} the first and second sections and the radial height of the paragraph 50 results in relation to the total axial width b: $$\mathrm{t}/\mathrm{b}=\mathrm{0}.\mathrm{95th}$$

As in particular from the Fig. 3 . 4 can be seen, the grooves 30, 40 in their radially inner groove bottom rounded chamfers, while the webs 40 have at their radially outer end faces inclined chamfers.

As soon as the plug-in foot 2 is inserted into the groove arrangement, it is fastened by two conical bolts (not shown) taken in the axial direction. There are two, in Fig. 1 . 5 recognizable holes 6.1, 6.2 provided that pass through the tabs 3, 4.

$${\mathrm{h}}_{\mathrm{B}\mathrm{2}}/\mathrm{b}=\mathrm{0},\mathrm{63.}$$

As in particular from Fig. 4 , In which the center lines of the two bolts are shown in phantom, it can be seen, the center of the radially upper bore of the radially outer end face of the webs 80 and the radially inner end face of the web 7 at a distance h _B1 , in Fig. 4 also dash-dotted line centerline of the radially inner bore 6.2 a radial distance h _B2 . Their ratio to the total axial width b is: $${\mathrm{H}}_{\mathrm{B}\mathrm{1}}/\mathrm{b}=\mathrm{0}.\mathrm{27}.$$

$${\mathrm{H}}_{\mathrm{B}\mathrm{2}}/\mathrm{b}=\mathrm{0}.\mathrm{63rd}$$

As continues in Fig. 5 recognizable, the direction of rotation (counterclockwise in Fig. 5 ) front end side of the tabs 3, 4 aligned parallel to the radial plane through the centers of the holes 6.1, 6.2, while the rear end in the direction of rotation is rotated in the circumferential direction corresponding to a blade pitch.

LIST OF REFERENCE NUMBERS

1

blade

2

Steckfuß

3

first or central lobes

3.1, 4.1

first section

3.2. 4.2

second part

3.i

axial

4

second or marginal lobe

4.i

inner axial side

4.a

axial end face

5

paragraph

6.1, 6.2

drilling

7

web

30

first or central groove

40

second or edge groove

40a

axial groove end face

50

paragraph

80

web

80.i

inner view page

81

first section

82

second part

Claims (14)

1. A moving blade for a flow machine, in particular a steam turbine with a plug-in root (2) with a first lobe (3) and two second lobes (4), which in axial direction (a) are arranged on both sides of the first lobe, wherein the first and the second lobes on axial sides (3.i, 4.i) facing one another comprise a shoulder (5) in axial direction in such a manner that the lobes comprise a first section (3.1, 4.1) located radially outside and a second section (3.2, 4.2) located radially inside, the axial extension (b_F3) is smaller than that (b_F1, b_F2) of the first section located outside, characterized in that based on an axial total width (b) between axial sides (4.a) of the two second lobes (4) facing away from one another, the radial height (h_F1/b) of the first section located radially outside lies in the range between 0.39 and 0.45, in particular between 0.40 and 0.44 and the radial height (h_F/b) of the second section located radially inside in the range between 0.40 and 0.46, in particular between 0.41 and 0.45.
2. The moving blade according to Claim 1, characterized in that the axial sides (4.a) of the two second lobes (4) facing away from one another are formed without shoulder.
3. The moving blade according to any one of the preceding claims, characterized in that based on the axial total width (b) between axial sides (4.a) of the two second lobes (4) facing away from one another, the radial total height (h/b) of the lobes lies in the range between 0.88 and 0.94, in particular between 0.89 and 0.93.
4. The moving blade according to any one of the preceding claims, characterized in that the shoulder (5), based on the axial total width (b) between axial sides (4.a) of the two second lobes (4) facing away from one another has a radial height in the range between 0.00 and 0.14, in particular between 0.00 and 0.12.
5. The moving blade according to any one of the preceding claims, characterized in that the axial width of the shoulder (5) steadily, in particular linearly tapers from the first to the second section.
6. The moving blade according to any one of the preceding claims, characterized in that based on the axial total width (b) between axial sides (4.a) of the two second lobes (4) facing away from one another, the first section (3.1) of the first lobe (3) located radially outside has an axial extent (b_F2/b) in the range between 0.21 and 0.27, in particular between 0.22 and 0.26; and/or the second section (3.2) of the first lobe (3) located radially inside has an axial extent (b_F3/b) in the range between 0.11 and 0.17, in particular between 0.12 and 0.16.
7. The moving blade according to any one of the preceding claims, characterized in that based on the axial total width (b) between axial sides (4.1) of a second lobe (4) located radially outside has an axial extent (b_F1/b) in the range between 0.16 and 0.22, in particular between 0.17 and 0.21; and/or the second section (4.2) of a second lobe (4) located radially inside has an axial extent (b_F3/b) in the range between 0.11 and 0.17, in particular between 0.12 and 0.16.
8. The moving blade according to any one of the preceding claims, characterized in that the first and the second lobes have two bores (6.1, 6.2) which are radially spaced from one another and aligned with one another for reaching through of a fastening pin, wherein based on the axial total width (b) between axial sides (4.a) of the two second lobes (4) facing away from one another, the centre point of a bore (6.1) located radially outside has a distance (h_B1/b) in the range between 0.24 and 0.30, in particular between 0.25 and 0.29 from the end of the first section (3.1, 4.1) located radially outside, and/or the centre point of a bore (6.2) located radially inside has a distance (h_B2/b) from the end of the first section (3.1, 4.1) located radially outside in the range between 0.60 and 0.66 in particular between 0.61 and 0.65.
9. The moving blade according to any one of the preceding claim, characterized in that the first and the second lobes (3, 4) are connected to one another by way of a web (7) located radially outside, the radial height of which based on the axial total width (b) between axial sides (4.a) of the two second lobes (4), (h_F1/b) facing away from one another lies in the range between 0.12 and 0.18, in particular between 0.13 and 0.17.
10. A flow machine, in particular steam turbine, with a groove arrangement for receiving a plug-in root (2) of a moving blade (1) according to any one of the preceding claims, wherein the groove arrangement comprises a first groove (30) for receiving the first lobe (3) and two second grooves (40) which are separated from the same by webs (80) for receiving the second lobes (4), wherein the webs on axial sides (80.i) facing one another have a shoulder (50) in axial direction in such a manner that the webs have a first web section (81) and a second web section (82) located radially inside, the axial extent (b_N2) is greater than that of the first web section (b_N1) located outside, characterized in that based on an axial total width (b) between axial sides (40.a) of the two second grooves facing away from one another, the radial height (T_N1/b) of the first web section (81) located radially outside lies in the range between 0.40 and 0.46, in particular between 0.41 and 0.45, and the radial height (t_N2/b) of the second web section (82) located radially inside lies in the range between 0.44 and 0.50, in particular between 0.45 and 0.49.
11. The flow machine according to Claim 10, characterized in that based on the axial total width (b) between axial sides (40.a) of the two second grooves (40) facing away from one another, the radial total height (t/b) of the webs (80) lies in the range between 0.92 and 0.98, in particular between 0.93 and 0.97.
12. The flow machine according to any one of the preceding Claims 10 to 11, characterized in that the webs (80) on their face end located radially outside and/or their end located radially inside comprise a chamfer.
13. The flow machine according to any one of the preceding Claims 10 to 12, characterized in that based on an axial total width (b) between axial sides (40.a) of the two second grooves facing away from one another, the first section (81) of a web (80) located radially outside has an axial extent (b_N1/b) in the range between 0.16 and 0.22, in particular between 0.17 and 0.21; and/or the second section (82) of a web (80) located radially inside has an axial extent (b_N2/b) in the range between 0.26 and 0.32, in particular between 0.27 and 0.31.
14. The flow machine according to any one of the preceding Claims 10 to 13, characterized in that the grooves (30, 40) are formed substantially complementarily to the first and the second lobes (3, 4).

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