HOUSING STRUCTURE FOR A TURBOMACHINE

The invention relates to a housing structure for a turbomachine, with a housing shell and at least one containment ring arranged in therein, wherein the housing structure surrounds a flow channel in a ring-shaped manner, in which at least one rotating stage with a guide vane arrangement and a rotating blade arrangement is arranged, as well as a turbomachine having such a housing structure.

BACKGROUND OF THE INVENTION

The invention relates to a housing structure for a turbomachine with a housing shell and at least one containment ring arranged therein, wherein the housing structure surrounds a flow channel in a ring-shaped manner, in which at least one rotating stage with a guide vane arrangement and a rotating blade arrangement is arranged.

In the case of failure of a rotating rotor element, housing structures of turbomachines are set up to prevent a penetration of the housing due to high active centrifugal forces so as to avert any danger to persons and goods in the surroundings of the turbomachine.

Accordingly, one function of a housing structure of a turbomachine is to prevent any radial escape of fragments, in particular fragments of rotating blades, in the radial direction out of the turbomachine. This function is referred to as “containment.” Especially for turbomachines with fast-rotating turbines, this requirement leads to very large wall thicknesses and a correspondingly detrimentally heavy weight of the housing structure. In addition, thick housing walls hinder the dissipation of heat, so that the containment capability of the walls is further degraded on account of high material temperatures. It is known to design housing structures of turbomachines in multishell constructions. In this way, it is possible to reduce the total wall thickness and accordingly the weight and the heat capacity of the housing structure of the turbomachine.

SUMMARY OF THE INVENTION

Based on this, an object of the present invention is to make available a housing structure with an improved containment capability.

Proposed for achieving this object is a housing structure for a turbomachine with a housing shell and at least one containment ring arranged in it, wherein the housing structure surrounds a flow channel in a ring-shaped manner, in which at least one rotating stage with a guide vane arrangement and a rotating blade arrangement is arranged. In this case, at least one containment ring extends essentially over the axial length of (only) one rotating stage and is arranged spaced radially apart from the housing shell at least in sections, whereby, owing to the radial spacing, at least one cavity is formed between the at least one containment ring and the housing shell.

The housing shell of the housing structure is formed to absorb the loads acting on the housing structure internally and externally during operation of the turbomachine. The housing shell in this case indeed has a containment function, but, in particular, as such, does not have an adequate containment capability.

Arranged in the housing shell is at least one containment ring, which surrounds a flow channel of the turbomachine in a ring-shaped manner. At least one rotating stage, which has a guide vane arrangement and a rotating blade arrangement, is arranged inside of the flow channel of the turbomachine. In particular, the guide vane of the rotating stage is connected to the housing shell. The at least one containment ring is arranged, in particular, concentrically with respect to the axis of rotation or turbomachine axis of the turbomachine. At least one containment ring is designed here as a closed ring, that is, as an unsegmented ring. In the case of a closed ring—in contrast to a ring composed of individual segments—it is possible to afford uniformly the containment capability along the circumference in a positionally independent manner. This is important for the construction design. As a closed ring, a containment ring can absorb, in particular, high circumferential forces, which, for example, result from forces acting radially on it. For example, the at least one containment ring is designed as a solid rotating part without, in particular, integrally bonded joints, as a turned wrought ring or turned cast part by way of example. Depending on the required ability to withstand loads, a containment ring can also be produced from a closed sheet metal ring with welded joints

In the proposed housing structure, at least one containment ring that is arranged in the housing shell extends essentially over the axial length of (only) one rotating stage, which comprises a guide vane arrangement and a rotating blade arrangement. As the term only in parentheses indicates, the formulation “one containment ring arranged in the housing shell extends essentially over the axial length of one rotating stage” is to be understood as meaning that the containment ring does not extend, in particular, over more than the axial length of a single rotating stage. The containment ring thus surrounds the region of a rotating stage in which, in the event of failure of a rotating blade or rotating blade arrangement (which, for example, can be designed as a rotor disk with blades mounted on it or as a one-part, integrated rotor disk or blisk), the fragments thereof are accelerated radially outward, for which reason a containment capability of the surrounding housing structure is required. Owing to the limitation of the axial length of the containment ring to about the axial length of a rotating stage, the containment capability can be fulfilled only locally by the at least one additional containment ring, so that the housing shell does not need to assume this function entirely. Accordingly, the containment capability of the housing structure is increased for a relatively low additional weight, which is also associated with advantages for the turbomachine in terms of weight.

In the proposed housing structure, at least one containment ring is arranged spaced radially apart, at least in sections, from the housing shell. A radial spacing of the containment ring from the housing shell, at least in sections, makes possible an appreciable thermal decoupling of the containment ring from the housing shell. In particular, by way of an abutting contact between a containment ring and the housing shell, a thermal coupling is also smaller than for a one-part thicker design of the wall of the housing shell.

The radial spacing between the at least one containment ring and the housing shell results in the formation of at least one cavity. The at least one cavity, in conjunction with an insulation effect, in particular of air present in it, makes possible an effective cooling function of the housing structure. Furthermore, the spacing of the at least one containment ring from the housing shell results in a larger radial extension of the containment region, so that, in the region of a cavity, there does not exist, in particular, any direct mechanical interaction between the at least one containment ring and the housing shell.

The proposed housing structure has containment regions in a multishell construction, as a result of which the load on the individual shells or containment rings can be kept in the more favorable damage mechanism of denting and subsequent rupturing under predominant tensile load. Cracks in a radial containment ring are stopped at the respective containment ring, so that an overstress due to a crack cannot lead to a rapid failure of the housing structure. Accordingly, the summed wall thickness and thus the weight of the housing structure and thus also of the turbomachine can be reduced. In particular, when a plurality of containment rings are used, each of these rings can be designed as a separate, isolated component, which, in itself, can be inspected separately and, as such, can be replaced. Accordingly, each containment ring can be manufactured individually, also from various materials, for example.

Beyond this, owing to the multishell construction of the housing structure in the containment regions, it is possible to use the containment rings arranged in one another to carry cooling air in order to keep the material temperature low and thereby the containment capability high.

In an embodiment, the housing structure has at least two containment rings that extend over the same rotating stage. In this case, the at least two containment rings are arranged, in particular, concentrically with respect to one another and radially in one another. Accordingly, the load on the individual containment rings can be kept in the already mentioned favorable damage mechanism of denting and subsequent rupture under predominant tensile load. It is also possible here to keep the wall thickness of each individual containment ring advantageously smaller than is the case when only one containment ring is used. Furthermore, a multipart construction of the housing structure also makes possible expanded possibilities for design of the housing structure and of the at least two containment rings. Thus, they can be designed to adapt better to the respective requirements of the housing structure, in particular in terms of containment capability and heat dissipation.

In an embodiment of the housing structure, the at least two containment rings are arranged spaced radially apart from one another at least in sections. Analogously to the spacing of a containment ring of the housing shell, this results in a thermal decoupling of the at least two containment rings from one another, whereby a thermal coupling by way of an abutting contact between two containment rings is smaller than for a one-part thicker design of a containment ring.

In an embodiment of the housing structure, the radial spacing between the at least one containment ring and the at least one second containment ring results in the formation of at least one cavity. The at least one cavity, in conjunction with an insulating effect of air present in it, makes possible, in particular, a further effective cooling function of the housing structure. Furthermore, the spacing of the at least two containment rings results in a larger radial extension of the containment region, so that, in the region of a cavity, in particular, there does not exist any direct mechanical interaction between the at least two containment rings.

In an embodiment of the housing structure, the at least one cavity is formed for carrying a flow of cooling air. In particular, the at least one containment ring and/or the housing shell are or is hereby designed in such a way that the at least one cavity or the walls thereof makes or make it possible to carry suitably a flow of cooling air streaming through the cavity, as a result of which a further improved cooling function of the housing structure can be achieved. In particular, the cavity has air inlet openings and air outlet openings arranged at suitable positions, as a result of which the cavity forms a flow channel through which a flow of air can stream and thus makes possible an improved cooling function of the housing structure. In particular, by way of a suitable design of at least one of the walls of, in particular, the at least one containment ring or the housing shell forming the cavity, the at least one cavity can be designed to divert a flow of cooling air in the cavity, in particular in the manner of a kind of labyrinth seal, as a result of which a further improved cooling effect can be achieved.

In an embodiment of the housing structure, the at least one cavity is formed so that cooling air can flow through it from an upstream lying cooling air source and, in another embodiment of the housing structure, the at least one cavity is formed so that cooling air can flow through it from a downstream lying cooling air source. Depending on the circumstances inside of the housing structure, the cavity and, in particular, the air inlet openings and air outlet openings thereof are formed and arranged so that a suitable flow of cooling air through the at least one cavity can be created in order to dissipate heat from the housing structure and thereby to improve further the containment function of the housing structure.

In an embodiment of the housing structure, at least one containment ring is arranged spaced apart, at least in sections, from the seal support radially surrounding the rotating stage. In particular, the at least one containment ring and the seal support hereby have essentially the same axial extension, as a result of which there are associated advantages in terms of the weight of the housing structure and thus of the turbomachine. Accordingly, the at least one containment ring after the seal support represents a first barrier for an element that is accelerated radially outward as a result of damage. In this embodiment, it can be advantageous for the at least one containment ring and the seal support to have, on at least one side, in particular an axial side, a common and/or interacting fastening, in particular at the housing shell or at a further element of the turbomachine and/or housing structure. In this way, a simple or efficient fastening of the at least one containment ring, in particular also in conjunction with the seal support, at the housing structure is made possible.

In an embodiment of the housing structure, a cavity that is formed between the containment ring and the seal support provides scaling against an axial flow and/or an insulating clement is arranged in it. A sealing of the seal support with respect to the radially surrounding region of the turbomachine against a throughflow of air, in particular also by use of an insulating clement, makes possible a reduction in the leakage flow in the region around the flow channel and thus also an improved efficiency of the turbomachine. Besides the sealing effect, an insulating element, in particular an insulating element surrounding the seal support, makes possible a further reduction in the heating of, in particular, the housing structure.

In an embodiment of the housing structure, a containment ring and the housing shell form at least one mount for a section of at least one adjoining guide vane. Such a mount can serve, in particular, for radial securing of the guide vane in the turbomachine. In such an embodiment, the containment ring can assume, beyond the containment function, also a structural function of the turbomachine.

In an embodiment of the housing structure, an axial front end and/or back end of at least one containment ring are or is arranged in a fastening region of the seal support and/or of the guide vane at the housing shell. This embodiment makes possible, in particular, besides a corresponding length of the containment ring and the seal support, a common fastening of the containment ring and the seal support on at least one axial side. In this way, in particular, it is possible for structural functions, for example, to be distributed onto a plurality of components and/or for structural functions to be used by a plurality of components, such as, for example, housing hooks and/or structural elements in the region of module interfaces. Correspondingly, advantages also ensue in an embodiment in which an axial front end and/or back end of at least one seal support are or is arranged in a fastening region of at least one containment ring and/or of the guide vane at the housing shell.

Preferably, the housing shell (35) (alone) does not have a required containment capability, but rather the required containment capability is afforded only together with the containment ring or containment rings. This makes possible a construction that is especially efficient in terms of weight and function.

In an embodiment of the housing structure, the axial extension of at least one of the containment rings lies in a region that extends from at least the axial extension of a rotating blade arranged inside of the containment ring up to twice the axial extension of such a rotating blade. The axial extension of a rotating blade hereby corresponds to the maximum axial distance between the leading edge (LE) of the blade and the trailing edge (TE) of the blade in the installed state. This maximum distance usually lies in a radial inner region of the blade.

In an embodiment of the housing structure, the at least one containment ring is fabricated from a material that differs from the material of the housing shell. The use of a material that, in particular, has properties suitable to meet the requirements of a containment ring, in particular in regard to strength and/or thermal conductivity, can further improve the containment function of the housing structure. Accordingly, in an embodiment, it is also possible to fabricate at least one containment ring from a material that differs from the material of at least one other containment ring in order to fulfill various requirements, in particular in regard to strength and/or thermal conductivity for further improvement of the containment function of the housing structure.

In an embodiment, the housing structure forms an outer housing of a turbomachine. On account of, in particular, a slender blade shape and the high speeds of rotation of turbine blades, increased requirements are placed on the containment capability at the housing structure of a turbomachine in the region of the turbine. The proposed housing structure is suited to fulfill such high requirements.

Proposed in an aspect is also a turbomachine with a housing structure that has at least one feature of the preceding described embodiments.

Further features, advantages, and possible applications of the invention ensue from the following description in conjunction with the figures. In general, it holds that features of the various aspects and/or embodiments described herein by way of example can be combined with one another insofar as this is not explicitly excluded in connection with the disclosure.

DESCRIPTION OF THE INVENTION

FIG.1shows a schematic illustration of an exemplary embodiment of a turbomachine10in a side view along the turbomachine axis S.

The turbomachine10has a housing structure30and, arranged one after the other in the flow direction R, a fan11, a compressor12, a combustion chamber13, and a turbine14, through which a gas flow can stream in the flow direction R or through which the gas flow streams during operation of the turbomachine10. The turbine14can thereby be connected via a shaft16to the compressor12and/or to the fan11in order to drive them. Depicted in the schematic illustration inFIG.1are the rotating stages20, each of which has a guide vane arrangement21and a rotating blade arrangement22.

FIG.2shows a schematic sectional illustration of an exemplary embodiment of a section of a housing structure30according to the invention for a turbomachine10, with a housing shell35that fulfills the requirements for absorbing all internal and external loads and fulfills a part of the containment requirement. The housing structure30surrounds the flow channel17of the turbomachine10in a ring-shaped manner, in which a plurality of rotating stages20, each with a guide vane arrangement21and a rotating blade arrangement22, are arranged. In one exemplary embodiment, two additional containment rings36,37are arranged in the housing shell35and are fabricated, for example, from various materials. As depicted inFIG.2, a respective additional containment ring36,37extends with respect to the housing shell35essentially over the axial length of a rotating stage20. Furthermore, it can be seen in the schematic illustration of the housing structure30inFIG.2, by way of example, that at least one containment ring36,37is arranged radially spaced apart from the housing shell35at least in sections.

In the embodiment illustrated schematically inFIG.2, by way of example, the housing shell35and the two containment rings36,37are each arranged radially spaced apart from each other. at least in sections. The radial spacing between the housing shell35and the containment ring36results in the formation a cavity46and, as a result of the radial spacing between the containment ring36and the containment ring37, a cavity47is formed. The cavities46and47here are formed in such a way that a flow of cooling air can be carried in them. For this purpose, an air inlet opening42and an air outlet opening43are arranged at respectively suitable positions, so that an improved cooling function of the housing structure30is made possible. For the exemplary embodiment illustrated inFIG.2, the cavities46,47are formed so that cooling air32can flow through them from a cooling air source lying downstream.

In the exemplary embodiment illustrated inFIG.2, the containment ring37is arranged spaced apart, at least in sections, from the seal support28radially surrounding the rotating stage20, at which a sealing element29, formed in a ring-shaped manner, is arranged. A cavity formed between the containment ring37and the seal support28is thereby sealed against an axial flow, in particular, a flow of air. Further shown schematically in the illustration inFIG.2is also an embodiment in which the containment ring37and the housing shell35form a mount33for a section of an adjoining guide vane of a guide vane arrangement21. Furthermore, in the depicted housing structure30, an axial back end of the containment ring37is arranged in a fastening region of the seal support28and the guide vane of a guide vane arrangement21is arranged at the housing shell35.

FIG.3shows a schematic sectional illustration of an exemplary embodiment of a section of a housing structure30according to the invention for a turbomachine10, with a housing shell35that fulfills the requirements for absorbing all internal and external loads and fulfills a part of the containment requirement. The housing structure30surrounds the flow channel17of the turbomachine10in a ring-shaped manner, in which a plurality of rotating stages20, each with a guide vane arrangement21and a rotating blade arrangement22, are arranged. In the exemplary embodiment, a containment ring36is arranged in the housing shell35and, for example, is fabricated from a different material than that of the housing shell35. As depicted inFIG.3, a respective containment ring36extends essentially over the axial length of a rotating stage20.

In the embodiment depicted inFIG.3, by way of example, the housing shell35and the containment ring36are arranged spaced radially apart from one another, at least in sections. The radial spacing between the housing shell35and the containment ring36results in the formation of a cavity46. The cavity46is formed here in such a way that a flow of cooling air can be carried in it. For this purpose, an air inlet opening42and an air outlet opening43are arranged at respectively suitable positions, so that an improved cooling function of the housing structure30is made possible. In the exemplary embodiment illustrated inFIG.3, the cavity46is formed in such way that cooling air32can flow through it from an upstream cooling air source.

In the embodiment illustrated inFIG.3, by way of example, the containment ring36is arranged spaced apart, at least in sections, from the seal support28radially surrounding the rotating stage20, at which a sealing element29is arranged in a ring-shaped manner. An insulating element49is hereby arranged in the cavity48that is formed between the containment ring36and the seal support28. Further arranged in the depicted housing structure30is an axial back end of the containment ring36in a fastening region of the seal support28and the guide vane of a guide vane arrangement21.