EP2848770B1 - Impeller blade of an axial turbo-machine and damping element - Google Patents

Description

The present invention relates to an impeller blade of an axial flow machine, with a blade root, an airfoil and a blade platform according to the preamble of claim 1. A generic impeller blade is for example from EP 2 280 151 A1 , of the EP 0 437 977 A1 , of the WO 2010/051453 A2 and the US 3,887,298 A known.

In turbomachines, especially in axial gas turbines, different mechanical damping systems for blades are used. For blades without internal cavities often positioning elements are integrated into the blades to achieve a stable position of the damping elements. These positional elements can lead to unwanted weight gain of the blades. For blades with internal cavities, which are used for example for cooling ducts, damping elements are often used, which must be adapted to given geometric conditions in the blade spaces.

An object of the present invention is to propose a blade for axial flow machines, which allows easy positioning of damping elements without position elements and thus without additional weight. It is another object of the present invention to provide a damping element for inclusion in a blade according to the invention.

The object of the invention is achieved by an impeller blade having the features of claim 1.

According to the invention, an impeller blade of an axial flow machine is proposed, which has at least one blade root, an airfoil and a blade platform. The impeller blade is fixed by means of the blade root on a rotor disk of the turbomachine. On the rotor disk further impeller blades are arranged, which are positioned in the circumferential direction. Furthermore, the Impeller blade on a pocket-shaped body, which is arranged below the blade and above the blade root and in the region of the blade platform. The bag-shaped body is bounded by axial and radial webs, preferably completely or in sections thereof. A damping element is arranged within these axial and radial webs. Furthermore, the bag-shaped body is arranged in or on a cavity of the blade platform. The cavity forms an enlarged cavity with another cavity of an impeller blade adjacent to the rotor disk. The pocket-shaped body also forms, with another pocket-shaped body with a blade adjacent to the rotor disk, an enlarged pocket-shaped body for receiving the damping element. In all the above and following embodiments, the use of the term "may be" or "may have" etc. is synonymous with "preferably" or "preferably has", etc., and is intended to explain embodiments of the invention.

Whenever numerical words are mentioned herein, those skilled in the art will understand these as indicating a numerically lower limit. If this does not result in a contradiction that is recognizable to the person skilled in the art, the person skilled in the art therefore always reads "at least one" or "at least one", for example, when specifying "a" or "one". This understanding is also encompassed by the present invention as the interpretation that a numerical word such as "a" may alternatively be meant as "exactly one" wherever technically possible for those skilled in the art. Both are encompassed by the present invention and apply to all number words used herein.

Advantageous developments of the present invention are the subject of subclaims and embodiments.

Embodiments of the invention may include one or more of the features mentioned below.

In the following, in particular gas turbines are described as axial flow machines purely by way of example, but without wishing to restrict axial flow machines to gas turbines.

In certain embodiments according to the invention, the blade root has a shape with which the blade root is connected to the rotor disk (in the axial direction of the gas turbine), in particular is detachably connected again. For example, the blade root can be pushed into a groove in the rotor disk. The blade root may have a so-called dovetail shape.

In some embodiments according to the invention, the blade platform has a front, a middle and a rear blade platform area, each viewed in the direction of flow of the gas turbine. The front and the rear blade platform area may be formed as a web or as a collar.

In some embodiments according to the invention, the blade platform, in particular the middle blade platform, connects the blade root with the blade leaf.

In certain embodiments of the invention, the airfoil, blade platform, and blade shape are made in one piece. Such a component may be referred to as "integral."

In certain embodiments of the invention, the impeller blade and the further impeller blades are arranged side by side on the rotor disk, in particular parallel next to one another.

In some embodiments of the invention, the bag-shaped body is cup-shaped or trough-shaped. The bag-shaped body may have a depth, a length and a width. The pocket-shaped body has in particular an open cross-section. The shape of the open cross section may be round, oval, square, polygonal or other shape.

In certain embodiments of the invention, the bag-shaped body has a rectangular shell shape with rounded corners. In particular, the radially outer wall and the radially inner wall is aligned parallel to the axis of rotation of the gas turbine. Furthermore, in particular the axially front and the axially rear wall (viewed in the flow direction) aligned radially. In a side view of the impeller blade according to the invention, the axially parallel walls can be referred to as horizontal walls and the walls in radial alignment as vertical walls.

In some embodiments of the invention, the walls of the pocket-shaped body are at least partially referred to as webs.

In certain embodiments according to the invention, the pocket-shaped body is bounded, at least in sections, by axial webs (or axially parallel as viewed in the flow direction) and the webs have a closed shape in a plane perpendicular to the flow direction.

In certain embodiments according to the invention, the axial and radial webs have an open shape in a plane perpendicular to the flow direction of the pocket-shaped body, wherein in particular the radially inner web is open. In other words, the radially inner web has a breakthrough, so that the bag-shaped body is open to the adjacent cavity.

In some embodiments of the invention, the cavity is cup-shaped or trough-shaped. The cavity may have a depth, a length and a width. The cavity has in particular an open cross section. The shape of the open cross section may be round, oval, square, polygonal or other shape. The cavity may have one or more undercuts.

In some embodiments according to the invention, the cavity has a wall, in particular towards the root of the blade. When juxtaposing with another impeller vane with a cavity so that the two cavities form a closed cavity, these walls can seal the cavity towards the blade root. However, a sealing gap (eg for compensating thermal expansions in the operating state) can be provided between the walls.

In some embodiments of the invention, the cavity is open to the blade root.

In certain embodiments of the present invention, the extended bag-shaped body is symmetrical to the two bag-shaped bodies of the paddle platform that form the extended bag-shaped body. The plane of symmetry is in particular the plane of the open cross-section of both pocket-shaped bodies, on which the two bodies are brought together.

In certain embodiments of the invention, a damping element is an element or body that dampens mechanical vibrations of a dynamic system. A damping element may be made of plastic or of another material. A damping element may have specific material properties for mechanical vibrations of a dynamic system (eg, specific visco-elastic properties). A damping element may have a specific weight for a dynamic system (eg, to dampen certain resonances or certain vibration frequencies). By way of example only, the weight of the damping element can be between 1.5 g and 4 g, in particular 2.5 g.

The damping element is solid in some embodiments of the invention. However, the damping element may also be hollow inside.

In some embodiments according to the invention, the widened cavity and / or the widened pocket-shaped body has a sealing gap, in particular a thermal sealing gap. A thermal sealing gap can compensate for material expansion during a material heating, thus avoiding possible stress peaks in the material or material distortion or material breakage.

In certain embodiments of the invention, the bag-shaped body has an opening to the cavity. An opening may be an open wall portion, an open boundary or a hole in a wall between the bag-shaped body and the cavity.

In certain embodiments of the invention, the opening between the bag-shaped body and the cavity is arranged parallel to the axis of rotation of the gas turbine.

The damping element has a length L _D in the axial direction a and a width W _D in the circumferential direction u perpendicular to the axial direction a, wherein the axial direction a is the axis of rotation of the gas turbine. The ratio of the length L _D to the width W _D is smaller than 1 according to the invention.

According to the invention the damping element is arranged in its longitudinal direction in the enlarged pocket-shaped body parallel to the axis of rotation of the turbomachine.

In certain embodiments of the invention, the damping element is configured in a cross section perpendicular to the longitudinal direction symmetrical to the vertical center axis of the damping element.

According to the invention, the damping element is designed trapezoidal or rectangular in a cross section perpendicular to the longitudinal orientation.

In some embodiments according to the invention, the length L _{D of} the damping element is at least 1 mm smaller than the length L _{T of} the extended pocket-shaped body of the impeller blade and / or the width W _{L of} the damping element is at least 1 mm smaller than the width W _{T of} the pocket portion of the impeller blade ,

In some embodiments of the invention, the damping element is arranged symmetrically in the enlarged pocket-shaped body of two adjacent blades.

Some or all embodiments according to the invention may have one, several or all of the advantages mentioned above and / or below.

With the impeller blade according to the invention damping elements can be used, their use no further positioning aids for the damping elements in make the blades necessary and thus advantageously cause no weight increase.

Due to its geometry, the damping element according to the invention is advantageously easy to handle and to be introduced into pocket-shaped bodies or other areas in impeller blades.

With the aid of the pocket-shaped bodies according to the invention and their geometries within cavities in impeller blades, damping elements can advantageously be positioned well, simply and accurately.

Fig. 1

zeigt eine Seitenansicht einer erfindungsgemäßen Laufradschaufeln mit einem Hohlraum und einem taschenförmiger Körper;

Fig. 2

zeigt eine Längsschnittdarstellung in Radialrichtung einer erfindungsgemäßen Laufradschaufel;

Fig. 3

zeigt eine Längsschnittdarstellung in Umfangsrichtung von zwei aneinandergereihten erfindungsgemäßen Laufradschaufeln mit Dämpfungselement;

Fig. 4

zeigt eine Querschnittdarstellung in Radialrichtung von zwei aneinandergereihten erfindungsgemäßen Laufradschaufeln mit Dämpfungselement;

Fig. 5

zeigt eine Seitenansicht einer weiteren erfindungsgemäßen Laufradschaufel mit einem geschlossenen taschenförmiger Körper; und

Fig. 6

zeigt eine Seitenansicht einer weiteren erfindungsgemäßen Laufradschaufel mit einem offenen taschenförmiger Körper.

The present invention will be explained in the following with reference to the accompanying drawings, in which identical reference numerals designate identical or similar components, by way of example. In each schematically simplified figures:

Fig. 1

shows a side view of an impeller blades according to the invention with a cavity and a pocket-shaped body;

Fig. 2

shows a longitudinal sectional view in the radial direction of an impeller blade according to the invention;

Fig. 3

shows a longitudinal sectional view in the circumferential direction of two juxtaposed impeller blades according to the invention with damping element;

Fig. 4

shows a cross-sectional view in the radial direction of two juxtaposed impeller blades according to the invention with damping element;

Fig. 5

shows a side view of another impeller blade according to the invention with a closed bag-shaped body; and

Fig. 6

shows a side view of another impeller blade according to the invention with an open pocket-shaped body.

Fig. 1 shows a side view of an impeller blade 100 according to the invention with a cavity 1 and a bag-shaped body. 3

The impeller blades 100 have a blade root 5, an airfoil 7 and a blade platform 9. The impeller vane 100 is integral, at least with respect to the vane root 5, the airfoil 7 and the vane platform 9. The impeller vane 100 is made of, for example, a casting alloy.

The blade platform 9 has a front 11, a middle 13 and a rear 15 blade platform area. The front 11 and the rear 15 blade platform area are formed as a shoulder or as a collar.

The bag-shaped body 3 has an approximately square shell shape with rounded corners and with a chamfer in the interior in the rear (seen in the axial direction, a downstream) area. The bag-shaped body 3 may be referred to as a closed box, with an opening in the axial-radial plane (in the direction perpendicular to the plane of the drawing). The pocket-shaped body 3 has two axial webs 29 and two radial webs 31.

The illustrated closed shell shape of the bag-shaped body 3 can in a further embodiment (see Fig. 6 ) have an opening or an opening in one of the webs or the walls, in particular to the cavity 1 out.

Fig. 2 shows a longitudinal sectional view of the impeller blade 100 according to the invention with the cavity 1, the pocket-shaped body 3 and a damping element 17th

A web width 19 at the rear end of the middle blade platform area viewed in the axial direction may, by way of example only, have a value of approximately 1.25 mm.

The damping element 17 has a square cross-sectional shape in this sectional view. The damping element 17 fills a part of the volume of the bag-shaped body 3.

Fig. 3 shows a longitudinal section AA (see in FIG Fig. 1 and in Fig. 2 the sectional planes AA) in the circumferential direction of two juxtaposed impeller blades 100 according to the invention with the damping element 17.

The damping element 17 has a width W _D and a length L _D. The damping element 17 is arranged centrally in the pocket-shaped body 3, surrounded by a respective gap.

As a result of the juxtaposition of two impeller blades 100, the two cavities 1 increase to an enlarged cavity 21. Likewise, the two pocket-shaped body 3 enlarge to an enlarged pocket-shaped body 23rd

Between the two impeller blades 100 remains after juxtaposing a sealing gap 25 which can compensate for example, thermal expansion of the individual components in the operating state or compensate.

Fig. 4 shows a cross-sectional view BB (see in FIG Fig. 1 and in Fig. 2 the sectional planes BB) in the radial direction r of two juxtaposed impeller blades 100 according to the invention with the damping element 17.

The damping element 17 has a trapezoidal cross-section and a height H _D and a width W _D. The damping element 17 is arranged centrally in the pocket-shaped body 3, but is located in the radially outer region on the walls and the axial webs 29 of the two bag-shaped body 3 (in the operating state, the damping element 17 is pressed due to the radial forces on the radially outer walls). Below the damping element 17, a gap 27 is shown.

Between the two impeller blades 100 remains after juxtaposing a sealing gap 25.

Fig. 5 shows a side view of another impeller blade 100 according to the invention with a, with respect to the plane shown in the axial direction and a radial direction r, closed pocket-shaped body 3. The pocket-shaped body 3 is referred to as closed, because the axial webs 29 and the radial webs 31 a have closed circumferential contour. In particular, this contour is closed with respect to the cavity 1.

Fig. 6 shows a side view of another impeller blade 100 according to the invention with a, in relation to the plane shown in the axial direction a and in the radial direction r, open pocket-shaped body. The bag-shaped body 3 is referred to as open, because the radially inner (in Fig. 6 the lower web) axial web 29 only about half of the total length in the axial direction a of the pocket-shaped body 3 has. In particular, the bag-shaped body 3 is open with respect to the cavity l. In other words, the pocket-shaped body 3 has an opening to the cavity 1.

LIST OF REFERENCE NUMBERS

100

impeller blade

a

axially; axially

r

radial; radial direction

u

Circumferential direction, perpendicular to the axial direction of the gas turbine

WD

Width of the damping element

LD

Length of the damping element

HD

Height of the damping element

1

cavity

3

pocket-shaped body

5

blade

7

airfoil

9

blade platform

11

front scoop deck area

13

middle scoop deck area

15

rear scoop deck area

17

damping element

19

web width

21

extended cavity

23

extended pocket-shaped body

25

sealing gap

27

lower sealing gap

29

axial web of the bag-shaped body

31

radial web of the bag-shaped body

Claims (7)

1. An impeller blade (100) of an axial turbomachine, with a blade root (5), an airfoil (7), and a blade platform (9), wherein the impeller blade (100) is mountable on a rotor disc by means of the blade root (5) and arranged with other impeller blades (100) on the rotor disc in the circumferential direction, wherein the impeller blade (100) has a pocket-like body (3) that is arranged beneath the airfoil (7) and above the blade root (5) as well as in the area of the blade platform (9), wherein the pocket-like body (3) is arranged in or on a hollow space (1) of the blade platform (9), wherein the hollow space (1) forms an enlarged hollow space (21) with another hollow space (1) of an adjacent impeller blade (100) on the rotor disc, wherein the pocket-like body (3), with another pocket-like body (3) of the rotor blade (100) that is adjacent on the rotor disc, forms an enlarged pocket-like body (23) for receiving a damping element (17), wherein the pocket-like body (3) is bordered at least by two axial (29) and two radial (31) crosspieces, wherein the damping element (17) is arranged within these crosspieces,
   wherein the impeller blade (100) further comprises the damping element (17), which is designed to receive in the enlarged pocket-like body (23) of the impeller blade (100), wherein the damping element (17) has a length L_D and a width W_D,
   wherein the damping element (17) is arranged in its longitudinal direction in the enlarged pocket-like body (23) parallel to the axis of rotation of the turbomachine, and
   wherein the damping element (17) is trapezoidal or rectangular in the cross section perpendicular to the longitudinal alignment of the damping element (17),
   characterized in that
   the ratio of the length L_D to the width W_D is less than 1.
2. The impeller blade (100) as set forth in claim 1, wherein the enlarged hollow space (21) has a sealing gap (25) or is connected to a sealing gap (25).
3. The impeller blade (100) as set forth in claim 1 or 2, wherein the enlarged pocket-like body (23) has a sealing gap (25) or is connected to a sealing gap (25).
4. The impeller blade (100) as set forth in any one of claims 1 to 3, wherein the pocket-like body (3) has an opening to the hollow space (1).
5. The impeller blade (100) as set forth in claim 4, wherein the opening is arranged so as to be parallel to the axis of rotation of the turbomachine.
6. The impeller blade (100) as set forth in any one of claims 1 to 5, wherein the damping element (17), in the cross section perpendicular to the longitudinal alignment of the damping element (17), is symmetrical to the vertical center axis of the damping element (17).
7. The impeller blade (100) as set forth in any one of claims 1 to 6, wherein the length L_D of the damping element (17) is at least 1 mm shorter than the length L_r of the enlarged pocket-like body (23) of the impeller blade (100) and/or the width W_L of the damping element (17) is at least 1 mm shorter than the width W_r of the pocket-like body (3) of the impeller blade (100).

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