EP2322763A1 - Turbine or compressor blade - Google Patents

Abstract

The vane has a vane blade (5) and a vane foot (6), where the vane blade is formed from a folded clutch-path of fiber-reinforced plastic. The vane foot has an elongated support and two holders (25) for anchorage of the vane in a corresponding groove of a turbine armature (1). The vane blade is suspended at the support by a strap (9). An independent claim is also included for an armature with a rotor.

Description

The invention relates to a blade of a turbine or a compressor.

A blade of a turbomachine normally comprises on the one hand an aerodynamically curved blade and on the other hand a blade root which serves to anchor the blade in a corresponding groove of a rotor. The rotor equipped with blades is referred to below as a rotor.

As a comparatively new material for the production of blades, carbon fiber reinforced plastic (CFRP) is also currently being considered. The manufacture of CFK requires e.g. advantageously a lower weight of the blade. However, disadvantageously, CFRP is comparatively less stable with respect to pressure loading. Such compressive stresses occur on a blade e.g. in the region of the blade root within the groove by the action of a rotational centrifugal force.

The invention has for its object to provide an at least partially made of fiber-reinforced plastic, in particular CFRP, manufactured blade for a turbine or a compressor, which is particularly durable, i. is durable. It is another object of the invention to provide a runner particularly resistant under operating conditions with blades made essentially of fiber-reinforced plastic.

With regard to the blade, this object is achieved according to the invention by the features of claim 1. Thereafter, the blade comprises, in addition to an aerodynamically curved blade, a blade root with an elongated or pin-shaped support, which in a preferred embodiment Metal is made. Furthermore, the blade root comprises at least two brackets, these preferably plate-shaped brackets on the carrier - at least in the radial direction - are fixed in position. Each holder is designed to anchor the blade in a corresponding hammer-shaped or fir tree-shaped groove of a rotor and can rest against the side walls thereof.

The airfoil is essentially made of stacked scrim webs of fiber reinforced plastic, in particular CFRP, which is guided (substantially between the brackets) around the carrier. In this case, the two web ends protruding beyond the carrier in each case are connected to one another in a planar manner to form a blade surface. The portion of the airfoil that is wrapped around the carrier forms a retaining loop for suspending the airfoil on the carrier. In terms of manufacturing technology, it is preferably provided to first manufacture the scrim for shaping the airfoil (that is to say the blade surface and the retaining loop) and subsequently to lift the airfoil thus produced onto the carrier. Alternatively, of course, the scrims may also be applied around the wearer to form and shape the adjoining airfoil.

In the intended mounting situation of the blade, this lies with its blade root, i. with the retaining loop of the blade and the carrier therein arranged in the groove of the rotor, while the airfoil substantially protrudes - with respect to the rotor - radially out of the groove.

Since the airfoil is suspended from the carrier by means of the retaining loop, rotationally induced centrifugal forces acting on the blade are absorbed substantially via the carrier. A direct power transmission between the blade and the rotor groove does not find, or only in a comparatively small scale. Therefore, the blade or its clutches is mostly under tension.

Since fiber-reinforced plastic is much more resistant to tensile loads than to compressive or shear loads, the blade and in particular its attachment area in the form of the blade root is therefore particularly resistant to long-lived operating conditions.

Advantageously, the use of fiber-reinforced plastic, in particular CFRP, for producing the airfoil generally opens the possibility of constructing an aerodynamically particularly favorable airfoil. This thus contributes to a reduced use of energy, which in turn is advantageously accompanied by a reduced CO2 development. Due to the lower weight of the fiber-reinforced plastic, the blades of such blades can also be larger than blade blades of metallic blades, with the same blade root. This also allows an increase in the mass flow.

In a particularly preferred embodiment of the invention, each of the holders in the region of the carrier protrudes on both sides beyond this at least substantially at right angles to the longitudinal extension of the blade. In other words, in such configurations, the supports extend beyond the scrim web at both sides in the region of the suspension of the airfoil, so that the scrim, at least in the region there, does not come into contact with the corresponding side surfaces of the groove (the groove flanks). Consequently, under centrifugal force, the blade mainly abuts only on the brackets on the groove flanks and not on the scrim, so that only the brackets experience compressive stresses. This avoids compressive stresses in the foot-side jaw regions, which could occur due to the centrifugal force, if the foot-side scrim would touch the groove flanks.

Conveniently, each of the brackets also protrudes on the intended radially inner (facing away from the blade surface) side of the blade beyond the blade, so that the scrim web is suspended without contact in the groove bottom of the rotor groove.

In a further embodiment of the invention, the blade root comprises two holders, in particular attached at the end of the carrier, and at least one third holder, which is fixed in position on the carrier spaced apart in the longitudinal direction of the carrier for each of the two end-mounted holders. Preferably, these additionally provided holders are evenly distributed over the length of the carrier. In this embodiment, the airfoil is expediently made of a plurality of scrim-webs, which are each suspended between two brackets on the carrier and thus fix the position of the central brackets in the longitudinal direction of the carrier. In principle, the two attachment positions of the brackets are selected on the elongated carrier depending on the center of gravity of the blade, so that even a non-end, but still arranged in the region of the support ends mounting position of the brackets can be useful.

Preferably, each of the brackets is provided with a corresponding with the cross section of the support passage through which the carrier is inserted in each case substantially fit. Optionally, the carrier is welded to the brackets.

In a preferred embodiment, the individual holders of the blade root are connected to each other by at least one edge part for stabilization thereof. this is aligned substantially parallel to the carrier.

Preferably, two flank parts are provided, which are each attached to the two side edges of each of the brackets, with which the respective holder projects beyond the blade. Accordingly, the two flank parts are preferably diametrically opposite with respect to the carrier. In particular, the attachment of the flank parts in turn takes place in such a way that they do not touch the scrim web, at least in the region in which the grips protrude beyond the airfoil. In trapezoidal brackets, the flank parts are preferably attached to the two legs of the trapezoid.

Conveniently, the flank parts are each positively or materially - preferably plugged or welded - connected to the brackets.

The carrier is preferably round or substantially triangular in cross-section. In a triangular shape, an isosceles triangle, in particular with rounded edges, is preferred, wherein the edge enclosed by the two legs in particular faces approximately the blade surface of the blade leaf.

Preferably, the support is provided on its surface with a sliding layer, in particular with a layer of polytetrafluoroethylene. As a result, if necessary, the innermost jelly web can slide relative to the carrier.

The clutch is formed in an advantageous embodiment of the invention substantially unidirectional, wherein it has a main fiber direction, which is aligned substantially along an operational centrifugal force direction. The blade is thus particularly stable against the resulting tensile forces. Additionally or Alternatively, the scrim is reinforced in the region of the blade root or in the region of the carrier by a three-dimensional interweaving of the fibers.

Advantageously, the blade is, at least in the region of its blade surface, provided on its surface with an erosion control layer, in particular of a particle composite or of a coated with a hard metal foil. This layer advantageously also improves the resistance of the blade to the ingress of water.

With regard to the rotor, the above-mentioned object is achieved according to the invention by the features of claim 12. Thereafter, the rotor comprises a rotor, in which at least one groove is inserted and at least one of the previously described blades according to the invention. The blade is fixed in position with its blade root in the groove.

Due to the comparatively low weight of the blades made essentially of fiber-reinforced plastic, each of the grooves provided in the rotor is advantageously made comparatively small. In addition, the entire runner is advantageously particularly light. Of course, the blade root to the blade can be made disproportionately large, if the blade according to the invention in a turbocharged Betriebskeansprüht a purely made of metal or stainless steel blade to replace.

Preferably, the groove and the brackets are matched to one another such that the brackets are respectively supported on the side surfaces of the groove. In particular, the brackets essentially fill the groove cross-section in an expedient manner.

Preferably, both the brackets and the groove in cross section are substantially trapezoidal in shape ("dovetail groove"). Other cross-sectional shapes, e.g. a "fir tree shape" or semi-circular shapes, are also possible for holders and Nutquerschnittskonturen.

In an advantageous embodiment of the invention, the supports of the blade are congruent to each other, wherein the groove has a uniform width and shape over its length.

In a preferred embodiment of the rotor this includes a plurality of each substantially axially aligned, evenly distributed over the circumference grooves, in particular in each groove in each case a blade is inserted and fixed in position there. In an alternative to this, a circumferential groove is introduced into the rotor of the turbine or compressor rotor, wherein a multiplicity of blades are accommodated in a row in this groove and fixed there.

FIG 1

in einem Querschnitt eine erste Ausführungsform eines Turbinenläufers mit einer Turbinenschaufel, umfassend ein Schaufelblatt sowie einen Schaufelfuß,

FIG 2

in einer schematischen Explosionsdarstellung den Schaufelfuß gemäß der ersten Ausführungsform, und

FIG 3

in Darstellung gemäß FIG 2 den Schaufelfuß gemäß einer zweiten Ausführungsform.

Two embodiments of the invention will be explained in more detail with reference to a drawing. Show:

FIG. 1

1 is a cross-section of a first embodiment of a turbine runner with a turbine blade, comprising an airfoil and a blade root;

FIG. 2

in a schematic exploded view of the blade root according to the first embodiment, and

FIG. 3

in illustration according to FIG. 2 the blade root according to a second embodiment.

Corresponding parts and sizes are always provided with the same reference numerals in all figures.

FIG. 1 shows in a slightly schematic sectional view of a turbine runner 1. The turbine runner. 1 comprises a rotor 2 made of stainless steel, in which evenly distributed over the circumference a plurality of axial grooves 3 are introduced. In FIG. 1 only a section of the rotor 2 in the region of a single axial groove 3 is shown. In the first embodiment shown here, each axial groove 3 is designed substantially as a so-called dovetail groove.

In the axial groove 3, a turbine blade 4 is received. The turbine blade 4 comprises an airfoil 5 (shown only partially here), as well as a blade root 6, which serves for anchoring the turbine blade 4 in the axial groove 3.

The blade 5 is made of several superimposed webs 7 of predominantly unidirectional CFRP scrim. The webs 7 are folded in such a way-preferably approximately in the middle-that a retaining loop 9 is formed in the region of the fold 8 formed during folding. Beyond this retaining loop 9 (in the illustration above), the web ends 10 lie flat against one another, wherein they are "baked" under shaping to form a blade surface 11 of the blade 5. The blade surface 11 projects approximately radially out of the axial groove 3 of the rotor 2.

A major fiber direction of the CFRP sheeting is oriented approximately along the tracks 7 so that each carbon fiber 12 of the CFRP sheeting is oriented substantially parallel to the longitudinal sectional surface of the airfoil 5 (substantially also each forming a loop).

At its - in the manufacturing state shown here - outside surface 13, the blade 5 is coated with an erosion protection layer 14. Alternatively, the erosion protection layer 14 is provided only in the area of the blade surface 11.

The blade root 6 comprises on the one hand as a carrier an elongated metal core 20, which rests in the retaining loop 9 for suspending the blade 5. The structure of the blade root 6 is based on a three-dimensional exploded view of the same in FIG. 2 explained in more detail. It can be seen that the metal core 20 is formed by a round rod made of stainless steel. The surface 21 of the metal core 20 may be provided with a sliding layer 22, for example made of PTFE. At its two ends 23, 24 of the metal core 20 is connected in each case with a holder 25. The two brackets 25 are essentially formed by congruent, isosceles, trapezoidal steel plates, which are corresponding to the dovetail-shaped axial groove 3 inserted into this.

Each holder 25 has approximately in its center of area a circular passage 26, in which the metal core 20 is inserted substantially accurately, the brackets 25 projecting about at right angles to the metal core 20 on this.

At the two legs 27 of each holder 25 each have a peripheral recess 28 is inserted into this. These recesses 28 are used for fixing two flank parts 30, with which the two brackets 25 are connected to the legs 27 in the assembled state.

Each flank part 30 is essentially formed by a rectangular, elongated steel plate. Each flank part 30 has on a side surface 31 a bulge 32, which extends in each case over the entire length of the corresponding flank part 30. The bulges 32 are in each case formed in a complementary manner to the recesses 28, so that the flank parts 30 with the bulges 32 in the recesses 28 are fixable in position.

Each flank part 30 also has a slightly angled longitudinal edge 33. In this case, each flank part 30 is dimensioned such that the straight part of the side surface 31 has a width b which corresponds approximately to the leg length L of the brackets 25. In the assembled state, the flank members 30 are mounted on both sides of two legs 27 of the two brackets 25, preferably welded. In each case with a side edge 34 opposite the edge 33, the edge parts 30 are arranged approximately flush with the long trapezoid side 35, the angled edge 33 protruding beyond the legs 27 on the short trapezoid side 36 in each case.

Out FIG. 1 it can be seen that the protruding edges 33 essentially serve to support the blade 5 in the mounting state in the tangential direction.

Out FIG. 1 It will be further appreciated that a mean width B ( FIG. 2 ) each of the brackets 25 is dimensioned sufficiently large that this protrudes in the region of the metal core 20 and the retaining loop 9, substantially at right angles to the blade surface 14 on both sides of the airfoil 5, so in particular each also via the scrim webs 7.

As a result, in particular radially at the level of the metal core 20 or the retaining loop 9, there is no contact between the flank parts 30 and the CFK scrim webs 7. Thus arises in this area even under the action of an operating during the turbine rotor 1 resulting (radially acting on the rotor) centrifugal force F no disadvantageous for the CFRP scrim pressure load.

During operation, the blade 5 therefore aligns with the centrifugal force F, as a result of which the blade 5 is almost exclusively under tensile load, against which the CFRP clutch, in particular also due to the favorable main fiber direction, is particularly resistant.

In the embodiment shown here, the two flank parts 30 are welded to the rotor 2 in the axial groove 3.

In FIG. 3 is the blade root 6 according to a second embodiment of the turbine rotor 1 and the turbine blade 4 shown. The second embodiment substantially corresponds to the first embodiment. In contrast, the blade root 6 has a third holder 25 here for more favorable load transfer, which is arranged approximately centrally in the longitudinal direction of the metal core 20. This middle bracket 25 is constructed analogously to the end-side brackets 25, wherein the metal core 20 is inserted through the passage 26 therethrough.

The airfoil 5 is formed here by two-part webs 7. In the region of the retaining loops 9, the webs 7 are each arranged in the longitudinal direction of the metal core 20 between the brackets 25, wherein they serve in addition to the suspension of the airfoil 5 for the axial fixation of the middle bracket 25.

An embodiment with four or more brackets 25 is also conceivable.

Claims (15)

A blade (4) for a turbine or a compressor, comprising an airfoil (5) and a blade root (6), - wherein the airfoil (5) is essentially made of a folded scrim web (7) made of a fiber-reinforced plastic, in particular CFK, in which in the region of the fold (8) ein.Halteschlaufe (9) is formed, and wherein a blade surface (11) is formed from the superimposed web ends (10), - Wherein the blade root (6) an elongated carrier (20), and at least two preferably both sides each fixed in position with this associated holders (25) for anchoring the blade (4) in a corresponding groove (3) of a turbine rotor (1), and - Wherein the airfoil (5) is suspended by means of the retaining loop (9) on the carrier (20). Shovel (4) according to claim 1, wherein each of the holders (25) in the region of the carrier (20) protrudes on both sides at least substantially transversely to the longitudinal extent of the blade (5). Shovel (4) according to claim 1 or 2, having at least one third holder (25) for anchoring in a corresponding groove (3), spaced apart in the longitudinal direction of the carrier (20) to each of the two, in particular end-mounted, holders (25) the carrier (20) is fixed in position. A blade (4) according to any one of claims 1 to 3, wherein the individual supports (25) are interconnected by at least one flank member (30) for stabilization and being oriented substantially parallel to the support (20). Blade (4) according to claim 4, wherein the flank part (30) is positively or materially connected to the holders (25). Blade (4) according to claim 4 or 5, having two flank parts (30) which are respectively attached to the side edges (27) of the two regions of the supports (25) projecting beyond the airfoil (5). A blade (4) according to any one of claims 1 to 6, wherein the support (20) is round or substantially triangular in cross-section. A blade (4) according to any one of claims 1 to 7, wherein the carrier (20) is made of metal. A blade (4) according to any one of claims 1 to 8, wherein the support (20) is provided on its surface (21) with a sliding layer (22). A blade (4) according to any one of claims 1 to 9, wherein the scrim (7) is formed substantially unidirectionally, and wherein the main fiber direction of the scrim is aligned as much as possible along an operational centrifugal force direction. Blade (4) according to one of claims 1 to 10, wherein the blade (5) is at least partially provided on its surface (13) with an erosion protection layer (14). Rotor (1) with a rotor (2), in which at least one groove (3) is introduced, and with at least one blade (4) according to one of claims 1 to 11, wherein the blade root (6) of the blade (4) in the groove (3) rests, and wherein this in the groove (3) fixed in position, with the rotor (2) is connected. A rotor (1) according to claim 12, wherein the brackets (25) are supported on the side surfaces of the groove (3). Rotor (1) according to claim 12 or 13, wherein the holders (25) substantially fill the groove cross-section. Rotor (1) according to any one of claims 12 to 14, wherein both the groove (3), and the holders (25) are formed substantially trapezoidal.

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