METHOD FOR MOUNTING A GAS TURBINE BLADE IN AN ASSOCIATED RECEIVING RECESS OF A ROTOR BASE BODY
A gas turbine blade in an associated receiving recess of a rotor base body includes a slot in the blade root and has the shape of a straight cylinder. A blade retaining plate has a first securing region and a second securing region interconnected by a shaft region; the shaft region having the shape of a straight cylinder configured to conform to the slot of the blade root. The shaft region comes to rest on a bottom of the receiving recess of the rotor base body; the first securing region being reshaped to form a first limit stop for a first end wall of the blade root; and the second securing region being reshaped to allow the blade root to be inserted along the insertion direction into the receiving recess. The second securing region of the blade retaining plate is subsequently reshaped to allow the second securing region to form a second limit stop for a second end wall of the blade root facing opposite the first end wall, and the blade root to be secured in position in the receiving recess.
This claims the benefit of German Patent Application DE 10 2013 214 933.6, filed Jul. 30, 2013 and hereby incorporated by reference herein.
The present invention relates to a method for mounting a gas turbine blade in an associated receiving recess of a rotor base body. The present invention also relates to a rotor for a gas turbine, as well as to a gas turbine having such a rotor.
BACKGROUNDIt is generally known from the related art to configure a blade retaining plate underneath a blade root of a gas turbine blade between the bottom of a blade root and the bottom of a receiving recess of a rotor base body and to bend the same in a way that secures the gas turbine blade against displacement relative to the rotor base body. A plurality of gas turbine blades are thereby attached in corresponding receiving recesses on the rotor base body until the resulting rotor is completely bladed. The gas turbine blade—rotor base body connection is also referred to as “live rim.” The rotor base body may be configured as a rotor disk or rotor ring, for example. Alternatively, it is known from the German Patent Application DE 1 426 797 A1 to use a resilient securing element having terminal transverse ribs that is configured in a slot in the rotor base body which deepens obliquely toward an end face of the rotor base body to secure the gas turbine blade in position.
SUMMARY OF THE INVENTIONThe inherent condition of the known methods and rotors that is to be considered as disadvantageous is that critical stress concentrations can occur in what is generally referred to as the live rim of the rotor during operation of an associated gas turbine in response to a tilting or displacement of the blade retaining plate.
It is an object of the present invention to provide a method for mounting a gas turbine blade in an associated receiving recess of a rotor base body that will make it possible to reliably prevent critical stress concentrations from occurring during later operation of the rotor. It is a further object of the present invention to provide a rotor of this kind, as well as a gas turbine that is at least equipped with such a rotor.
A method for mounting a gas turbine blade in an associated receiving recess of a rotor base body includes at least the steps of providing the gas turbine blade; this including a slot in the blade root thereof that extends along the same and has the shape of a straight cylinder whose longitudinal axis extends in parallel to a direction of insertion of the blade root into the receiving recess; providing a blade retaining plate that has a first securing region and a second securing region that are interconnected by a shaft region; the shaft region having the shape of a straight cylinder that is configured to conform to the slot of the blade root; configuring the blade retaining plate to allow the shaft region to come to rest on a bottom of the receiving recess of the rotor base body; the first securing region being reshaped to form a first limit stop for a first end wall of the blade root; and the second securing region being reshaped to allow the blade root to be inserted along the insertion direction into the receiving recess; the blade root of the gas turbine blade being inserted along the insertion direction into the receiving recess of the rotor base body until the first end wall of the blade root rests against the limit stop formed by the reshaped first securing region; the shaft region of the blade retaining plate being configured within the slot of the blade root and filling the same when the first end wall comes to rest against the limit stop; and the second securing region of the blade retaining plate being reshaped to enable the second securing region to form a second limit stop for the second end wall of the blade root facing opposite the first end wall, and the blade root to be fixed in position in the receiving recess. In other words, in contrast to the related art, it is provided that the blade root of the gas turbine blade features a slot for fully accommodating the shaft region of the blade retaining plate. Both the slot and the shaft region have the shape of a straight cylinder and are configured to conform to one another. In the context of the present invention, a straight cylinder is understood to be a body that has two parallel, plane, congruent base surfaces and one lateral, respectively cylindrical surface that is formed by parallel straight lines; both the parallel straight lines, as well as the longitudinal axis of the cylinder extending orthogonally to the base surfaces. The length of the cylinder, and thus the length of the longitudinal axis thereof is defined by the distance between the two base surfaces. In general, the base surfaces may have any desired plane shape, and have a square, rectangular, circular, elliptical, etc., form, for example. The base surfaces preferably have a square or rectangular shape, so that the shaft region has a parallelepiped, respectively cuboid shape in this case. Thus, both the slot, as well as the shaft region are free of local raised portions, indentations, oblique surfaces or the like. At least during mounting, respectively in the mounted state, both the longitudinal axis of the shaft region, as well as the longitudinal axis of the slot extend in parallel to an insertion direction, respectively an insertion vector of the blade root, into the associated receiving recess, thereby making it readily possible for the blade root to be linearly inserted into the receiving recess that has the blade retaining plate mounted therein. It is understood that it is generally not necessary to reshape the second securing region if it is also possible for the blade root to be inserted along the insertion direction into the receiving recess without deforming the second securing region. Since the shaft region of the blade retaining plate fills the slot of the blade root when the gas turbine blade is mounted, and since the securing regions of the blade retaining plate rest against the mutually opposing end walls of the blade root, the blade retaining plate is located in a defined position within the slot of the blade root, as well as within the receiving recess, making a tilting or displacement of the blade retaining plate relative to the receiving recess or relative to the gas turbine blade impossible during later operation of an associated gas turbine. Thus, this also precludes any critical stress concentrations in the live rim area of the finished rotor. Moreover, the gas turbine blade may be attached to the rotor base body with the aid of one single further component, namely the blade retaining plate. There is no need for any further components. Finally, the blade retaining plate that is accommodated in certain regions of the slot also reduces the leakage cross section in the area of the gas turbine blade—rotor base body connection. The gas turbine blade may generally be disassembled in a reverse sequence.
One advantageous embodiment of the present invention provides that the slot in the blade root of the gas turbine blade be produced by the deposition and/or ablation of blade material. In terms of structural design, this provides a simple method for producing the slot in the blade root. Moreover, this makes it possible to furnish existing gas turbine blades, which do not yet have a slot in the blade root thereof, with a slot, thereby allowing the use thereof in the context of the present invention. When the slot is produced by the deposition of blade material, the blade root is enlarged radially inwardly. Here the advantage is derived that the geometric cross section of passage is advantageously reduced in the slot bottom of the receiving recess, thereby achieving a reduction in leakage flows and a corresponding increased efficiency of the gas turbine during operation of the associated gas turbine. The blade retaining plate is hereby advantageously used both for securing the gas turbine blade in position, as well as for sealing the receiving recess.
Other advantages are derived by rounding at least one edge in the area of the blade root slot prior to placement of the shaft region of the blade retaining plate within the slot. In other words, a gas turbine blade is used that does not have any sharp edges, at least in the slot region. Due to the absence of sharp edges in the area of the blade root and, thus, in the area of the blade retaining plate configured in the slot, material of the blade root, of the blade retaining plate and/or of the receiving recess is reliably prevented from breaking away or tearing.
In a further embodiment of the present invention, a mechanically especially stable connection of the gas turbine blade to the rotor base body may be achieved by providing a gas turbine blade whose blade root has at least one dovetail portion and/or at least one fir tree portion. It may be provided that the blade root of the gas turbine blade feature a plurality of dovetail and/or fir tree portions in the radial direction.
A second aspect of the present invention relates to a rotor for a gas turbine that includes a rotor base body having at least one receiving recess; a blade root of an associated gas turbine blade being configured in the receiving recess and secured in position by a blade retaining plate. It is at least provided in accordance with the present invention that the gas turbine blade include a slot in the blade root thereof that extends along the same and has the shape of a straight cylinder, whose longitudinal axis is disposed in parallel to a direction of insertion of the blade root into the receiving recess. In addition, it is provided that the blade retaining plate have a first securing region and a second securing region that are interconnected by a shaft region; the shaft region having the shape of a straight cylinder that is configured to conform to the slot of the blade root. Finally, the blade retaining plate is configured in the receiving recess in a way that allows the shaft region thereof to be configured within the slot of the blade root and fill the same; the first securing region being reshaped in a way that allows it to form a first limit stop for a first end wall of the blade root; and the second securing region being reshaped in a way that allows the second securing region to form a second limit stop for a second end wall of the blade root facing opposite the first end wall. Critical stress concentrations in the live rim of the rotor blade body are hereby prevented in the case of the rotor according to the present invention since the blade retaining plate is located in a defined position and is not able to tilt within the slot in the blade root. The rotor base body may be configured as a rotor disk or rotor ring, for example. Further advantages resulting herefrom and features thereof will become apparent from the descriptions of the first inventive aspect; advantageous embodiments of the first inventive aspect being considered to be advantageous embodiments of the second inventive aspect and vice versa.
One advantageous embodiment of the present invention provides that the blade root and the shaft region of the blade retaining plate fill the receiving recess of the rotor base body at least virtually completely. A geometrically especially small leakage cross section is hereby provided in the slot bottom of the gas turbine blade - rotor base body connection, thereby advantageously enhancing the efficiency of a gas turbine equipped with the rotor according to the present invention. It is alternatively or additionally provided that the shaft region of the blade retaining plate be designed to conform to the slot of the blade root. In other words, it is provided that the geometry of the shaft region correspond exactly to that of the slot, so that, on the one hand, the shaft region is completely configured within the slot and, on the other hand, also completely fills the same.
Further advantages are derived when the blade root of the gas turbine blade is designed to be edge-free at least in the area of the slot thereof. In other words, it is provided that the blade root not have a sharp-edged form at least in the area of the slot thereof, whereby material is reliably prevented from breaking away or tearing during operation of the rotor.
A third aspect of the present invention relates to a gas turbine, in particular an aircraft engine, having at least one rotor that includes a rotor base body having at least one receiving recess in which a blade root of an associated gas turbine blade is configured and secured in position by a blade retaining plate. The present invention provides that the gas turbine blade be mounted in the receiving recess of the rotor base body using a method in accordance with the first inventive aspect and/or that the rotor be designed in accordance with the second inventive aspect. The features derived herefrom and the advantages thereof are to be inferred from the descriptions of the first, respectively the second inventive aspect.
Other features of the present invention are derived from the claims, the exemplary embodiment, as well as in light of the drawings. The aforementioned features and combinations of features, as well as the features and combinations of features mentioned in the exemplary embodiment may be used not only in the particular stated combination, but also in other combinations without departing from the scope of the present invention. Specifically,
To assemble gas turbine blade 14 provided with blade root 34 according to the present invention, blade retaining plate 26 is first placed on the bottom of receiving recess 24, allowing shaft region 38 to extend therethrough. Beforehand or subsequently, a first securing region 40a is bent radially upwards to form a limit stop for a first end wall 42a of blade root 34. As is discernible in
In particular in
To prevent damage to blade retaining plate 26 or blade root 34, both during assembly, respectively disassembly, as well as during operation of associated gas turbine 10, blade root 34 is designed to be free of sharp edges and the like, in particular in the area of slot 36 thereof, to prevent material from breaking away or tearing. Sharp edges may form, for example, in the manufacturing of slot 36 at blade root 34. Such sharp edges are, therefore, preferably rounded. To this end,
Claims
1. A method for mounting a gas turbine blade in an associated receiving recess of a rotor base body, comprising the following steps:
- providing the gas turbine blade having a blade root, the turbine blade including a slot in the blade root, the slot extending along the blade root and having the shape of a straight cylinder whose longitudinal axis extends in parallel to a direction of insertion of the blade root into the receiving recess;
- providing a blade retaining plate having a first securing region and a second securing region interconnected by a shaft region, the shaft region having the shape of a further straight cylinder configured to conform to the slot of the blade root;
- configuring the blade retaining plate to allow the shaft region to come to rest on a bottom of the receiving recess of the rotor base body, the first securing region being reshaped to form a first limit stop for a first end wall of the blade root and the second securing region being reshaped to allow the blade root to be inserted along the insertion direction into the receiving recess;
- inserting the blade root of the gas turbine blade along the insertion direction into the receiving recess of the rotor base body until the first end wall of the blade root rests against the limit stop formed by the reshaped first securing region, the shaft region of the blade retaining plate being configured within the slot of the blade root and filling the same when the first end wall comes to rest against the limit stop; and
- reshaping the second securing region of the blade retaining plate to allow the second securing region to form a second limit stop for a second end wall of the blade root facing opposite the first end wall and the blade root to be secured in position in the receiving recess.
2. The method as recited in claim 1 wherein the slot in the blade root of the gas turbine blade is produced by the deposition and/or ablation of blade material.
3. The method as recited in claim 1 wherein at least one edge in the area of the slot of the blade root is rounded prior to placement of the shaft region of the blade retaining plate within the slot.
4. The method as recited in claim 1 wherein the blade root has at least one dovetail portion or at least one fir tree portion.
5. A rotor for a gas turbine comprising:
- a rotor base body including at least one receiving recess;
- a gas turbine blade having a blade root configured and secured in position in the at least one receiving recess by a blade retaining plate, the gas turbine blade including a slot in the blade root extending along the blade root and having the shape of a straight cylinder whose longitudinal axis extends in parallel to a direction of insertion of the blade root into the receiving recess;
- the blade retaining plate having a first securing region and a second securing region interconnected by a shaft region, the shaft region having the shape of a further straight cylinder configured to conform to the slot of the blade root, the blade retaining plate being configured in the receiving recess in such a way that the shaft region thereof is configured within the slot of the blade root and fills the slot, the first securing region being reshaped to form a first limit stop for a first end wall of the blade root, and the second securing region being reshaped to allow the second securing region to form a second limit stop for a second end wall of the blade root facing opposite the first end wall.
6. The rotor as recited in claim 5 wherein the blade root and the shaft region of the blade retaining plate fill the receiving recess of the rotor base body completely, or the shaft region of the blade retaining plate is designed to conform to the slot of the blade root.
7. The rotor as recited in claim 5 wherein the blade root of the gas turbine blade is designed to be edge-free at least in the area of the slot thereof.
8. A gas turbine comprising the rotor as recited in claim 5.
9. An aircraft engine comprising the gas turbine as recited in claim 8.
10. A gas turbine comprising at least one rotor including a rotor base body having at least one receiving recess in which a blade root of an associated gas turbine blade (14) is configured and secured in position by a blade retaining plate, wherein the gas turbine blade is mounted in the receiving recess of the rotor base body according to the method recited in claim 1.
11. An aircraft engine comprising the gas turbine as recited in claim 10.
Type: Application
Filed: Jul 29, 2014
Publication Date: Feb 5, 2015
Inventors: Sebastian KALTENBACH (Muenchen), Armin Kammerer (Roehrmoos), Alexander Boeck (Kottgeisering)
Application Number: 14/445,847
International Classification: F01D 5/02 (20060101);