Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Reexamination Certificate
2001-09-19
2003-05-13
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
C416S19300A, C416S248000
Reexamination Certificate
active
06561764
ABSTRACT:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/EP00/02209 which has an International filing date of Mar. 13, 2000, which designated the United States of America, the entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
The invention relates to a gas turbine rotor with an internally cooled gas turbine blade which has a blade foot and a blade platform, and with a disk possessing transverse disk grooves, into which the blade root is inserted. The blade platform is arranged outside an outer circumference of the disk and possesses, on an end wall portion of one longitudinal side, a recess into which is inserted an insert strip which engages into a corresponding recess of blade platform of a second gas turbine blade and bridges and seals off an interspace between the two blade platforms.
BACKGROUND OF THE INVENTION
DE-A1-198 10 567 discloses a sealing plate for a gas turbine moving blade. When cooling air supplied to the gas turbine moving blade escapes into the high-temperature fuel-gas duct, this results, inter alia, in a reduction in the power output of the gas turbine. The sealing plate, which is inserted into the gas turbine blade, is intended to prevent cooling air from emerging. Sealing is carried out not only by way of the sealing plate, but also by way of various sealing pins which are installed between the platforms of two moving blades. A multiplicity of sealing elements is necessary in order to produce the desired function of sealing against the emergence of cooling air.
DE-B-1 258 662 discloses a covering device for guiding the cooling gas from gas turbine disks, which consists of a plurality of individual segments sealed off relative to one another by means of sealing strips. Sealing-off is therefore carried out in an additional device which is placed in front of the gas turbine disk and the gas turbine moving blades pushed into the latter. This increases the number of elements required for constructing the seal.
U.S. Pat. No. 4,523,890 discloses sealing elements for the root regions of turbine blades. Sealing serves for reducing the cooling-air losses at the lower end of the roots. To hold the sealing elements, it is necessary to introduce into the turbine disk holding grooves into which the sealing elements are to be pushed. Complicated production steps are therefore necessary.
Similar arrangements of sealing elements are also used to prevent the ingress of hot gas into the platform region or the internal cooling system of a gas turbine moving blade. Such an ingress of hot gas may lead to severe damage to the gas turbine moving blade. In order to prevent this, a plurality of sealing elements are inserted into the blade platform on that side of the blade platform of the gas turbine moving blade which faces the hot-gas stream.
Disadvantages of the built-on parts described for sealing the platform of the gas turbine moving blade prove to be that the seal is constructed from a multiplicity of elements and therefore it becomes difficult to install the seal in the gas turbine moving blade. In addition, various securing elements also have to be attached, in order to prevent the gas turbine moving blade from slipping out of place laterally in the rotating disk of the gas turbine or even falling out.
SUMMARY OF THE INVENTION
The object of the invention is to specify a gas turbine rotor with an internally cooled gas turbine blade, in which both sealing against the ingress of hot gas and the emergence of cooling air and the securing of the gas turbine blade are to be effected at a low outlay and at the same time are highly reliable.
The object is achieved in that the recess reaches as far as a disk-side base of the blade platform, and the insert strip has a form fit to the disk which secures against axial displacement in the direction of insertion of the gas turbine blade.
The specific design of the insert strip, in particular the extension of the latter as far as the blade platform, ensure, on the one hand, that the blade platform is sealed off at its end wall portion against the penetration of hot gas or the outflow of cooling air. Sealing can be produced in a simple way and is performed by a single element which can be individually adapted in its shape to various platform configurations.
At the same time, the insert strip ensures that the gas turbine blade is fixed axially in the disk of the gas turbine rotor. The gas turbine blade, which is inserted with its blade root into a transverse disk groove of the disk and the platform of which is arranged outside the circumference of the disk, therefore cannot be displaced relative to the transverse disk groove to an undesirable extent. Axial fixing is ensured by the form fit of the insert strip to the disk. As a result, in particular, the gas turbine blade is prevented from slipping out of place in the direction of insertion in which the forces acting during the running of the gas turbine may be preferentially directed. This type of fixing can be installed and removed in a particularly stable and simple way and has low susceptibility to faults.
After thermal expansion which occurs due to the load exerted by the hot gases flowing onto the wing, the insert strip returns completely into its neutral position, for example without being continuously displaced in relation to this, which, after a few runs of the gas turbine rotor, would lead to a failure of the functions of the securing element against displacement in a direction of insertion of the gas turbine blade in the transverse disk groove.
The sealing and fixing of the gas turbine blade are accordingly carried out by way of a single element, the insert strip. This constitutes an appreciable improvement, as compared with known systems, in which a multiplicity of elements and, in conjunction with this, a high outlay in terms of installation were necessary for this purpose. Another advantage, in addition to the simplicity with which securing is carried out by means of a single insert strip, is its good handleability and the possibility of quickly exchanging, cleaning or repairing it.
Preferably, highly heat-resistant material which is stable with respect to chemical attacks is to be used, so that the onflowing hot gas does not deform or corrosively destroy the insert strip. The proposed designs of the insert strip can easily be produced with these materials because of its simple shape and have high durability even where relatively brittle materials are concerned.
Comprehensive protection against axial displacements in both directions of insertion of the transverse disk groove is afforded in that there is a recess on each of the end wall portions of one longitudinal side of the blade platform, and in that its insert strips bear on two mutually opposite disk end faces and protect against axial displacements of the gas turbine blade relative to the disk. Securing against axial displacement or against a forward and backward slipping of the gas turbine blade inserted into the transverse disk groove is ensured by the two mutually opposite insert strips which in each case have a securing form fit on the two mutually opposite disk end faces of the disk. Axial movement is inhibited in as much as axial displacements of the gas turbine blade relative to the disk either are inhibited completely or are possible only within a predetermined small scope.
If there is a recess on each of the end wall portions of each longitudinal side of the blade platform and insert strips are inserted into said recesses, each gas turbine blade is secured by four insert strips, two strips in each case ensuring securing in one direction of insertion. In this way, even if one insert strip fails or is lost, the gas turbine blade is held securely against displacement in the transverse disk groove by the remaining three. In this case, in each case two gas turbine blades share between them the two insert strips seated between them in the longitudinal side of the blade platform.
The insert strips can be mounted with little outlay and are
Harness Dickey & Pierce PLC
Siemens Aktiengesellschaft
Verdier Christopher
LandOfFree
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