Patent Application
20180100398
This application claims priority to German Patent Application DE10 2016 219 815.7 filed on Oct. 12, 2016, the entirety of which is incorporated by reference herein.
The invention relates to a rotor blade assembly group for an engine with a ring-shaped or disc-shaped blade carrier with multiple rotor blades.
Such a rotor blade assembly group can for example be part of a compressor or a turbine of the engine, in particular of a gas turbine engine. Here, the rotor blades are provided along a circle line about a central axis of the rotor blade assembly group, wherein this central axis usually coincides with the rotational or central axis of the engine. The blade carrier, at which the rotor blades are integrally formed or at which separately manufactured rotor blades are fixated via respectively one blade root, has a carrier section that extends radially inwards in the direction of the central axis with respect to the rotor blades. This carrier section usually forms a part of a disc body, which is formed—in consideration of the available installation space—with a comparatively large surface, so as to be able to withstand the loads that result from the fast rotation of the rotor blade assembly group about the central axis as they occur during operation of the engine. The higher the rotational speed of the blade carrier with the rotor blades and thus the load on the blade carrier, the larger the carrier section and consequently the weight of the blade carrier.
What is proposed in DE 101 63 951 C1 and DE 102 18 459 B3 for reducing the weight of a rotor blade assembly group and a rotor comprising the same is to provide a stiffening structure with first and second stiffening elements made of a metal matrix composite (“MMC”, in short) at the blade carrier at a connection area of the carrier section. At that, respectively one stiffening element is embodied as a fiber-reinforced MMC ring and is arranged at respectively one face side of the blade carrier. Thus, for example two MMC rings are fixedly attached in a mirror-inverted manner at a connection area of a radially inwardly extending carrier section of a blade carrier, and namely at a first frontal face side and at a second rear face side of the blade carrier. Through the additional stiffening elements in the form of MMC rings, higher rotational speeds can be applied to the blade carrier while the carrier section has a smaller radial extension, and thus the blade carrier can be subjected to higher loads. Thanks to the MMC rings, the weight of the blade carrier is considerably lower as compared to a blade carrier with the same loadability having a larger carrier section.
In the rotor blade assembly groups that are proposed in DE 101 63 951 C1 and DE 102 18 459 B3, the stiffening elements in the form of the MMC rings are fixated independently of each other in a form-fit manner at respectively one face side of the carrier section, and where necessary additionally shrunk onto an axially extending projection of the connection area. At that, each MMC ring is separately axially secured at the respective face side of the carrier section and arranged above the corresponding axially extending projection at the connection area of the carrier section with respect to a radially outwardly pointing transverse direction. The fixation and in particular axial securing of the individual stiffening elements in the form of MMC rings is thus comparatively laborious. Further, the manufacture of the blade carrier with the connection area, which has to additionally integrate a form-fit axial securing possibility, is complicated and entails relatively high costs.
The invention is thus based on the objective to provide a rotor blade assembly group that is improved in this respect, and in which the previously mentioned disadvantages are avoided or at least reduced.
This objective is achieved with rotor blade assembly groups with features as described herein.
What is proposed according to a first aspect of the invention is a rotor blade assembly group for an engine with a ring-shaped or disc-shaped blade carrier having multiple rotor blades, in which at least two, first and second, stiffening elements of a stiffening structure, which is fixedly attached at a connection area of a carrier section of a blade carrier, are respectively connected not only to the connection area, but in which also the first and second stiffening elements are additionally connected to each other.
Through the additional connection of the stiffening elements, which are arranged at different face sides of the blade carrier, an axial securing of the stiffening elements at each other and with respect to the blade carrier is achieved, without each individual stiffening element itself having to be separately axially secured at the carrier section of the blade carrier. Here, according to the first aspect of the invention, the solution according to the invention is based on the basic idea that, at the connection area of the blade carrier, stiffening elements are arranged at first and second face sides of the blade carrier that are facing away from each other—with the stiffening elements being preferably embodied so as be symmetrical to a transverse direction that extends radially with respect to the central axis and so as to be facing each other —, and that are axially secured through their additional connection to each other (with respect to the central axis).
Here, in one embodiment variant, the axial securing of both stiffening elements of the stiffening structure is realized via at least one separate connection element of the stiffening structure that directly connects the two stiffening elements arranged at different face sides, and secures them axially with respect to each other. In this manner, none of the stiffening elements is axially displaceable relative to the other stiffening element. Both stiffening elements are thus supported at the carrier section in a position according to the intended use.
At that, the solution according to the invention is principally independent of whether the rotor blades are formed integrally with the blade carrier, and the rotor blade assembly group is thus realized in Bling or Blisk design, or whether the rotor blades are separately manufactured and fixated at the blade carrier. In one embodiment variant, the ring-shaped or disc-shaped blade carrier is for example equipped with multiple individual rotor blades, which are respectively fixated at the blade carrier via a blade root of a rotor blade.
In one embodiment variant, a previously mentioned separate connection element for the connection of the first and second stiffening elements, which are arranged at different face sides of the blade carrier, to each other extends through a passage hole in the carrier section. This passage hole can be a central passage hole through the blade carrier, for example in the form of a bore. In that case, the at least one separate connection element for example extends through such a central passage hole of the blade carrier, so as to axially fixate the two stiffening elements relative to each other.
In particular in this case, the at least one separate connection element can at least partially enclose the first and second stiffening elements, so that at least parts of both stiffening elements are received between two sections of the connection element inside a cross section along the central axis. The connection element can for example have a U-shaped cross section, so that both stiffening elements, which are arranged at different face sides of the blade carrier, are received at least partially between two radially protruding legs or edges of the connection element.
Alternatively or additionally, the at least one connection element can be formed as a tensioning part that is held in a form-fit and/or force-fit manner at both first and second stiffening elements, respectively exerting a force on the first or second stiffening element that is arranged in the connection area which acts in the direction of the other second or first stiffening element. Thus, the stiffening elements are for example tensioned against each other by means of the tensioning part. Here, the tensioning part itself is held in a form-fit and/or force-fit manner at both first and second stiffening elements, for example due to an extension of the tensioning part meshing with an opening or groove in the respective stiffening element, or reversely due to a lateral extension of the respective stiffening element meshing with an opening or groove of the tensioning part.
In one embodiment variant, it is provided that at least the first or second stiffening element is formed in a ring-shaped manner. In a further development, both stiffening elements are formed in a ring-shaped manner. Compared to multiple, for example ring-segment shaped, stiffening elements per face side, the ring-shaped design of one individual stiffening element per face side has the advantage that it is simpler and quicker to assemble.
In one embodiment variant, at least one of the first and second stiffening elements is manufactured at least partially from a metal matrix composite (“MMC”, in short) for the purpose of weight reduction. Here, at least one of the first and second stiffening elements can have a core of a metal matrix composite provided with an exterior coating. The core may for example consist of a reinforced titanium in MMC design, i.e., in particular of a titanium matrix with a ceramic reinforcement.
In one embodiment variant, the blade carrier has a passage hole that extends axially, for example centrally, with respect to the central axis and that is radially delimited by an inner edge of the carrier section. A section of the first or second stiffening element that is formed by a metal matrix composite extends axially below this inner edge of the carrier section. Accordingly, it is provided in such a variant that the radially inner edge of the carrier section, which delimits the preferably centrally provided passage hole in the ring-shaped or disc-shaped blade carrier, is at least partially edged by the at least one stiffening element, for example with an L-shaped cross section, and a section of the stiffening element extends below the connection area with respect to a radially outwardly oriented transverse direction. Consequently, the section of the first or second stiffening element arranged at the first or second face side, which is made of a metal matrix composite, extends below the inner edge in the direction of the other face side, and consequently provides a support below this inner edge through the metal matrix composite. The extension of the metal matrix composite in the axial direction below an inner edge of the carrier section can thus serve to provide an additional support below the rotor blades and the thus formed circumferentially extending rotor blade row, and result in a more robust stiffening structure.
In one embodiment variant, the connection area forms at least one axial projection that is enclosed by a first or second stiffening element in a form-fit manner, so that the axial projection is received at least partially between a radially outer and a radially inner section of this stiffening element. In this way, an axially projecting section of the connection area extends between a radially outer and a radially inner section of the stiffening element. At that, the axial projection can for example be formed at the connection area so as to project locally in a web-like manner or so as to project circumferentially in a ring-shaped manner, and can for example be received between the two sections of the stiffening element inside a groove-shaped recess of the stiffening element. The form-fit enclosing of an axial projection of the connection area by at least one of the stiffening elements does not only allow for an improved force application into and support through the respective stiffening element, but also an improved connection of the respective stiffening element to the connection area of the blade carrier. In this manner, the stiffening element can for example be axially pushed on or plugged on in a simple manner at the face side of the blade carrier and the at least one axial projection, and is held at the blade carrier in a directly radially secured manner by means of the form-fit enclosing of the axial projection.
Alternatively or additionally to a form-fit enclosing of an axial projection of the connection area, the blade carrier can have a passage hole that extends axially with respect to the central axis and that is radially delimited by an inner edge of the carrier section, and a first or second stiffening element of the stiffening structure can extend axially with at least one section below this inner edge of the connection area. Thus, in that case, a first or second stiffening element of the stiffening structure extends with at least one section axially along the inner edge of the connection area from one face side in the direction of the other face side of the blade carrier. Through the extension of the stiffening element below the radially inner edge of the blade carrier, an improved support and stiffening of the blade carrier in the area of the carrier section can be achieved independently of the use of the metal matrix composite—and in particular independently of the design explained above, in which a section of the stiffening element made of a metal matrix composite extends axially below an inner edge.
Besides, the design of at least one axial connection area that is enclosed by the stiffening element in a form-fit manner as well as the axial extension of at least one section of a first or second stiffening element below an inner edge of the connection area for improving the mountability of the stiffening structure and the loadability of the blade carrier can be advantageously combined with an additional connection of the first and second stiffening elements arranged at different face sides of the blade carrier, but can also be used independently therefrom.
Accordingly, what is proposed according to a second aspect of the invention is a rotor blade assembly group for an engine with a ring-shaped or disc-shaped blade carrier having multiple rotor blades, in which a stiffening structure is provided that has at least one stiffening element at a first or second face side of the blade carrier. At that, the connection area according to the second aspect of the invention forms at least one axial projection that is enclosed by the at least one stiffening element in a form-fit manner, so that the axial projection is received at least partially between a radially outer and a radially inner section of the stiffening element. Alternatively or additionally, it is provided according to the second aspect of the invention that the blade carrier has a passage hole that extends axially with respect to the central axis of the blade assembly group and that is radially delimited by an inner edge of the carrier section, and the at least one stiffening element of the stiffening structure extends axially below this inner edge of the connection area, that is, from the face side in the direction of the other face side, with at least one section.
An axial projection of the connection area can principally extend in parallel to the central axis and thus substantially perpendicular to a radially extending face side of the carrier section. However, the axial projection can also take an angle to the face side that is different from 90°.
Further, a transitional area between a substantially radially extending face-side carrier surface at the connection area and an end of the projection integrally formed therewith can be curved in a concave manner. Here, the degree of curvature and thus the course of a straight line at this transitional area can be chosen differently depending on the engine and/or the position of the rotor blade assembly group, depending on how strong the forces occurring at the connection area are and with which force components these extend, for example radially and tangentially. For instance, at the transitional areas, a straight line extends at an angle of 0° to 45° with respect to the radial direction. The degree of curvature and thus the enclosed angle can for example also be realized depending on the used manufacturing material for the stiffening element. In particular with a view to a metal matrix composite and the fibers provided therein, which can bear higher stresses in the circumferential direction about the central axis than in a tangential direction, a smaller angle and thus a stronger concave curvature for the transitional area (and thus a less “soft” transition between the face surface and projection) may be advantageous.
The at least one axial projection can be part of a profile of the connection area that has a T-shaped, I-shaped or firtree-shaped cross section. In a T-shaped profile, two projections that axially extend in opposite directions are integrally formed at the connection area. Accordingly, in a profile that is formed in an I-shaped manner, i.e., in the manner of the cross sectional profile of a double T-girder, two pairs of such two projections extending axially in opposite directions are provided, being arranged at a radial distance to one another. Provided in a firtree-shaped profile are at least two or three pairs of projections that extend axially in opposite directions and are arranged radially above each other and at a distance to each other, with their axial extension decreasing or increasing in a step-wise manner along a radial direction.
In one embodiment variant, a T-shaped, I-shaped or firtree-shaped profile of the connection area extends at least in certain sections along a circle line about the central axis. In a further development, the connection area of the ring-shaped or disc-shaped blade carrier is provided with a complete circumferential T-shaped, I-shaped or firtree-shaped profile.
In particular in a firtree-shaped cross sectional profile of the connection area, a for example ring-shaped stiffening element can be arranged at each face side of the blade carrier, being provided with a correspondingly matching cross sectional profile as a counter-part and encloses multiple axial projections, which are defined by the firtree-shaped cross sectional profile of the connection area, in a form-fit manner. By means of such a connection between a respective stiffening element and the connection area of the blade carrier, the radial loads that occur during operation of the engine can be guided more efficiently from the blade carrier into the stiffening structure. Here, the occurring forces are also introduced into the stiffening structure at different radial positions and thus in a distributed manner, so that the force transmission between the blade carrier and the stiffening structure is improved. Additionally, the connection and safe fixation of the stiffening structure at the blade carrier is considerably simplified.
In a possible further development, sealing elements and/or cooling openings can be provided at an axial projection of the connection area, in particular at an axial projection of a T-shaped, I-shaped or firtree-shaped cross sectional profile of the connection area. In that case, cooling openings may for example serve for supplying cooling air to the blade carrier.
What can in particular be provided with a rotor blade assembly group of the invention, according to the first as well as the second aspect of the invention, is a gas turbine engine in which the weight of one or multiple rotor blade rows of a compressor and/or of one or multiple rotor blade rows of a turbine is considerably reduced as compared to the rotor blade rows as they have been commonly used so far in practice, while at the same time the mounting of the stiffening structure and its axial securing is comparatively simple. At that, rotor blade assembly groups that respectively form one rotor blade row including the stiffening structures fixedly attached thereat according to the invention can be arranged axially behind each other and fixated at each other in a torque-proof manner. However, of course it is also possible to combine a rotor blade assembly group embodied according to the invention for forming a rotor blade row with a further rotor blade assembly group of a further rotor blade row that is not embodied according to the invention.
The accompanying Figures illustrate possible embodiment variants of the invention by way of example.
The air that is conveyed via the compressor V into the primary flow channel is transported into the combustion chamber section BK of the core engine where the driving power for driving the turbine TT is generated. For this purpose, the turbine TT has a high-pressure turbine 13, a medium-pressure turbine 14, and a low-pressure turbine 15. The turbine TT drives the rotor shaft S and thus the fan F by means of the energy that is released during combustion in order to generate the necessary thrust by means of the air that is conveyed into the bypass channel B. The air from the bypass channel B as well as the exhaust gases from the primary flow channel of the core engine are discharged via an outlet A at the end of the engine T. Here, the outlet A usually has a thrust nozzle with a centrally arranged outlet cone C.
As is known, rotor blade assembly groups which rotate about the central axis M and respectively have one rotor blade row and in which the rotor blades are provided at a ring-shaped or disc-shaped blade carrier, are used in the area of the (axial) compressor with its low-pressure compressor 11 and its high-pressure compressor 12 as well as in the area of the turbine TT. In principle, the ring-shaped or disc-shaped blade carrier can be integrally bladed, and can thus be manufactured in Bling or Blisk design. Alternatively, it is possible to fixate individual rotor blades at a ring-shaped or disc-shaped blade carrier via their respective blade roots. For this purpose, a blade root may for example be axially inserted into a fastening groove of the blade carrier and axially secured at the respective blade carrier.
By way of example,
Due to the rotational speeds and the resulting loads, each blade carrier 23, 24 or 25 of a rotor blade assembly group 2a, 2b or 2c of the state of the art has a radially inwardly extending carrier section 230, 240 or 250. A disc-shaped carrier section 250 of the rear rotor blade assembly group 2c for example serves for the rotatable mounting of the rotor blade assembly groups 2a, 2b and 2c that are connected to one another in a torque-proof manner. In the carrier section 230, 240 of two (with respect to the flow direction through the engine T) frontal rotor blade assembly groups 2a and 2b, a central passage hole O1 or O2 is provided mainly for the purpose of weight reduction, for example in the form of a bore. With view to the necessary installation space of the rotor blade assembly groups 2a and 2b as well as their weight, it is most important which radial extension the blade carriers 23 and 24 have in order to be able to withstand the loads that occur during operation.
In the different variants of a solution according to the invention, which are for example illustrated in
However, what different variants of stiffening structures 5a and 5b respectively have in common is that two ring-shaped stiffening elements, which are positioned opposite each other, are arranged in the form of (MMC) stiffening rings 50 and 51 at the face sides of the respective blade carriers 23 or 24. On the one hand, the stiffening rings 50 and 51 are directly connected to each other, preferably via at least one additional connection element. On the other hand, both stiffening rings 50, 51 respectively enclose one connection area 231 or 241 of the respective carrier section 230 or 240 in a form-fit manner at least in certain sections, with the carrier section 230 or 240 having a continuous profile in the circumferential direction that comprises at least two projections axially extending in opposite directions. Here, in the one variant of the rotor blade assembly group 2a, the connection area 231 is provided with a firtree-shaped (cross sectional) profile, while in the other rotor blade assembly group 2b of
As is illustrated based on
In the present case, both stiffening rings 50 and 51 extend so far axially below the inner edge of the carrier section 231 or 241 of the blade carrier 23 or 24 with respectively one enclosing section 50.1 or 51.2, that the stiffening rings 50 and 51 directly adjoin each other with their enclosing sections 50.1 and 51.2. Consequently, the stiffening rings 50 and 51 that are provided on both sides of the connection area 231 or 241 and that are respectively supported at the respective connection area 231 or 241 in a form-fit manner directly abut each other and the stiffening structure 5a or 5b thus created extends through the entire passage hole O1 or O2.
The stiffening structure 5a or 5b with the stiffening rings 50 and 51, which are arranged at face sides of the blade carrier 23 or 24 that are facing away from each other, mainly receives radially acting forces. But at the same time, a simpler mounting as well as a simpler radial securing of the stiffening rings 50 and 51 to be mounted at the blade carrier 23 or 24 is facilitated as a result of the circumferential profile of the connection area 231 or 241.
In a firtree-shaped cross sectional profile according to the variants of
Provided at the individual stiffening rings 50 and 51 are grooves corresponding to the projections 2310.1 to 2312.1 or 2310.2 to 2312.2 of a face side, so that the stiffening ring 50 or 51 that is respectively attached at a face side encloses each projection 2310.1 to 2312.1 or 2310.2 to 2312.2 at the respective face side in a form-fit manner, and accordingly each projection 2310.1 to 2312.2 is respectively received between a radially further internally and a radially further externally positioned section of the respective stiffening ring 50 or 51. Through a form-fit connection between the blade carrier 23 and the stiffening rings 50 and 51 that is thus formed, radial loads as they occur during operation of the engine T are introduced into the stiffening structure 5a in a manner distributed across the firtree-shaped profile. In addition, the stiffening structure 5a is thus radially fixated at the carrier section 230 of the blade carrier 23 already by plugging on the stiffening rings 50, 51, without any additional fastening means.
For axially fixating the two stiffening rings 50 and 51, at least one connection element is provided, which is not shown in any more detail in
For instance, an individual connection element can be used. In one variant, this individual connection element can extend at the stiffening structure 5a circumferentially in a ring-shaped manner, or can extend at least across the larger part of a radially inner circumference of the stiffening structure 5a. Alternatively, multiple local connection elements can be provided for axial securing in a manner offset with respect to one another along the circumference.
For instance, a connection element 6 can be formed with a U-shaped cross section, as is shown in
In the cross sectional view, both stiffening rings 50 and 51 are received between the two legs or edges 60, 61 of the connection element 6. At that, a force can be applied to each of the stiffening rings 50, 51 via the two respectively radially extending edges or legs 60, 61 that engage at the face side, pressing the stiffening ring 50, 51 in the direction of the other stiffening ring 51 or 50. Thus, the connection element 6 acts as a tensioning part, that axially tensions the two stiffening rings 50 and 51 against each other.
In contrast to the variants of
In the embodiment variants of
In
Regarding a firtree-shaped profile of the connection area 231 of a blade carrier 23, it is further illustrated by way of example based on the cross sectional rendering of
A geometry of the firtree-shaped profile can further be characterized by an angle α taken by two tangents with respect to each other, which are respectively applied in across the sectional view along the central axis M at the ends of the axial projections 2310.1 to 2312.1 or 2310.2 to 2312.2 of a face side. The larger the angle α, the larger the axial extension of the firtree-shaped profile and/or the larger the gradation in the axial extension between the projections 2310.1 to 2312.1 or 2310.2 to 2312.2 that are provided at a face side.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 219 815.7 | Oct 2016 | DE | national |
