Patent ID: 12209510

DETAILED DESCRIPTION

Aspects of the present disclosure provide a blisk whose safety behavior is improved in the event of damage or extreme loads.

An aspect of the present disclosure provides a blisk in a gas turbine, which includes at least one blade with a blade airfoil and a blade root, and a platform, in particular a rotor disk platform. The blade may be integrally attached to the platform. A fillet may be arranged at the blade root and between the blade airfoil and the platform. The fillet may merge into the blade airfoil at a blade connection, and the fillet may merge into the platform at a platform connection. The fillet may extend with a longitudinal extent around the blade root and a transverse extent from the platform connection on the platform to the blade connection on the blade airfoil. The fillet may have a variable radius along the transverse extent. The at least one blade, the platform and the corresponding connection includes the fillet form a blade-platform connection, and also different blade-platform connections can be provided on a blisk.

According to an aspect, the present disclosure provides for the variable radius, at least in a first section of the fillet, that has a minimum radius which, at least in the first section along the transverse extent of the fillet, is spaced from the platform by at least 15%, preferably at least 30%, of the transverse extent. The distance from the platform advantageously prevents the platform and thus the rotor disk from cracking in the event of damage. Such a distance of the minimum radius to the platform thus represents a crack-influencing device. This advantageously introduces a first means of decoupling static and dynamic stresses in the blade into the geometry. This significantly reduces the risk of disk failure. It may be provided that the distance to the platform is at least 35%, in particular at least 40%, especially preferably at least 45% of the transverse extent of the fillet. This can favorably influence crack growth into the blade and away from the rotor disk in the event of damage to the blade. In addition, it may be provided that the minimum radius is not only linear, but also band-shaped. The minimum radius can be constant at least in the first section over a central region of the transverse extent. Accordingly, the variable radius should be viewed as a function that can also have constant values in sections. The structural band of a minimum radius formed in this way can extend along the longitudinal extent of the fillet, whereby the fillet can have a radius with a constant minimum value or a straight line along the transverse extent in the structural band. The first section of the fillet can make up 5% of the longitudinal extent of the fillet. However, it can also be provided that the first section is larger or smaller. For example, the first section may account for 2%, 3% or 4% of the longitudinal extent of the fillet, but the first section may also account for 10%, 15% or 20% of the longitudinal extent of the fillet.

In a preferred embodiment of the present disclosure, the minimum radius along the transverse extent of the fillet to the blade airfoil can be distanced at least 30% of the transverse extent. This can advantageously ensure that even damage that occurs at a low radial height of the blade does not lead to crack growth in the disk, but instead runs in the blade. In this way, a second means of decoupling static and dynamic stresses in the blade can be advantageously introduced into the geometry. It may be provided that the distance to the blade is at least 35%, in particular at least 40%, especially preferably at least 45% of the transverse extent of the fillet. The resulting structure of the fillet radius along the transverse extent is trough-shaped or U-shaped.

In a further preferred configuration of the blisk, the fillet is completely concave along its transverse extent, at least in the first section. The fact that no convex or straight areas are provided means that the component stresses can be favorably distributed and, in addition to the lower aerodynamic effects, lower mechanical stress peaks are advantageously achieved.

In addition, it may be provided that the course of the radii of the fillet along its transverse extent is also completely concave, at least in the first section. This means that the course of the radii has a monotonically increasing first derivative along the transverse extent with a zero crossing at the minimum radius.

In addition, in a further configuration of the blisk, it can be provided that the minimum radius at least in the first section is 5 mm or less, in particular 3 mm or less, especially preferably 2 mm or less. Such small radii allow the material stresses to be specifically influenced, so that crack propagation into the disk can be advantageously reduced or prevented. This is a particularly advantageous third decoupling means that allows static and dynamic stresses to be influenced separately from each other. It may be provided that the minimum radius is at most 5 mm, in particular at most 4 mm. This means that the remaining extent of the radius has larger values, which allows a particularly good distribution of surface stresses.

In a further embodiment of the blisk, the variable radius has a maximum radius on the blade airfoil and/or on the platform, at least in the first section, the variable radius having a monotonically decreasing course between the maximum radius and the minimum radius along the transverse extent of the fillet. As a result, a blade connection with a maximum radius can be formed between the fillet and the blade, and/or a platform connection with a maximum radius can be formed between the fillet and the platform. The fact that the maximum radius is formed at the blade connection and/or at the platform connection means that there are no local stress concentrations along the transverse extent of the fillet that could contribute to component failure.

Furthermore, in a still further embodiment, at least in the first section, a ratio of the minimum radius to the maximum radius on the blade airfoil and/or on the platform can be at least 1.5, in particular at least 5, especially preferably at least 5. Such a radius distribution along the transverse extent in at least one section along the longitudinal extent of the fillet can bring about a targeted increase in stress to influence cracking.

In a complementary or alternative embodiment of the blisk, wherein the blade comprises a blade chord extending from a leading edge to a trailing edge, it may be provided that a ratio of the maximum radius to the minimum radius on the blade airfoil and/or on the platform is maximum at a maximum point of the fillet located between 5% and 95% of a blade chord. The projected distance of the maximum point on the blade chord to the leading edge is at least 5% of the chord length of the blade. This can favorably influence crack growth into the blade and away from the rotor disk in the event of damage to the blade. It may be provided that the distance to the platform is at least 5%, 10%, 15%, 20%, preferably at least 25%, 30%, 35%, in particular at least 40%, or particularly preferably at least 45% of the transverse extent of the fillet. It may be provided that the distance to the blade is at least 5%, 10%, 15%, 20%, preferably at least 25%, 30%, 35%, in particular at least 40%, or particularly preferably at least 45% of the transverse extent of the fillet. It may be provided that the maximum point is arranged in the first section.

In a further embodiment, it may be provided that the fillet has a second section spaced from or adjacent to the first section, wherein at least in the second section a ratio of the maximum radius to a minimum radius on the blade and/or on the platform is at most 1.5, in particular at most 1.2, particularly preferably at most 1.1. In particular, areas can be specifically created in this way that can withstand one of the static or dynamic stresses in particular. This advantageously provides a fourth decoupling means that allows static and dynamic stresses to be specifically influenced separately from one another.

According to a further aspect of the present disclosure, the ratio of the maximum radius (rmax) to the minimum radius (rmin) can be larger on the suction side than on the pressure side of the blade airfoil, in particular the ratio on the suction side can be on average twice as large, preferably three times as large, as on the pressure side.

In a preferred further embodiment, the first section extends from a leading edge to a trailing edge of the blade. However, it may also be provided that the first section extends between 30% and 70% of a blade chord of the fillet. Furthermore, other or smaller local sections are also proposed, which have the characteristics of the first section. For example, such a section may be spaced from the leading edge by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% of the chord length. Such a section may also, for example, be spaced from the trailing edge by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% of the chord length.

In addition, in a further embodiment, it may be additionally provided that the first section is arranged on the pressure side and/or the suction side of the blade. The arrangement of the first section on the suction and/or pressure side can be used specifically to compensate for the static stresses due to a blade inclination. This provides a fifth decoupling means that allows static and dynamic stresses to be influenced separately from each other.

In an advantageous further development, the blisk can be designed in such a way that the first section is arranged on the suction side of the blade and the second section is arranged on the pressure side of the blade. This opposing arrangement of the two different sections of the fillet can have a particularly beneficial effect on stresses that occur due to a pitch of the blade.

A further preferred embodiment of a blisk according to the present disclosure in a gas turbine, which embodiment may be claimed independently, comprises at least one blade with a blade airfoil and a blade root, a platform, in particular a rotor disk platform, wherein the blade is integrally attached to the platform, a fillet arranged at the blade root and between the blade airfoil and the platform, wherein the fillet merges into the blade airfoil at a blade connection and wherein the fillet merges into the platform at a platform connection. The fillet extends with a longitudinal extent around the blade foot and a transverse extent from the platform connection on the platform to the blade connection on the blade airfoil, wherein the fillet has a variable radius along the transverse extent. The at least one blade, the platform and the corresponding connection comprising the fillet form a blade-platform connection, wherein different blade-platform connections can also be provided on a blisk.

According to an aspect of the present disclosure, a composite fillet is provided. Hereby, the radial offset/distance of the blade connection from the platform connection ABdist is greater than the offset of the platform connection relative to the blade connection EBdist when viewed in the circumferential direction. The more precise definition of the boundary curves represents (in addition to the patent already filed for the qualitative radius curves) a further possibility for influencing the control of the static and dynamic load distribution of the component. Thus this element also contributes to an increase in damage tolerance (no crack growth in the disk).

During the structural-mechanical design work, it was shown that so-called “composite blends” have a positive effect on the separation of static and dynamic loads.

In addition to the radii of the fillet contour, the definitions of the rotor-side boundary curve (endwall boundary/platform connection) and the blade-side boundary curve (airfoil boundary/blade connection) are of decisive importance.

According to the present partial aspect of the present disclosure, the limiting curves can be defined parametrically based on the maximum profile thickness (tmax0) of the blisk blade and/or the blade airfoil.

The platform connection/endwall boundary can be created by a rolling ball, a variable rolling ball or an offset of the blade surface around a constant/variable value.

The value range for the area to be protected is EBdist=0.70 . . . 1.35*tmax0

The blade connection/airfoil boundary can hereby be created by a rolling ball, a variable rolling ball or an offset of the annular space surface by a constant/variable value.

The value range for the area to be protected is ABdist=0.8 . . . 2.0*tmax0

In addition, the requirement ABdist>EBdist applies in all areas to guarantee an elliptical shape of the composite blend.

In other words, the radial offset/distance of the blade connection from the platform connection can be in a range ABdist=0.8 . . . 2.0*tmax0 and the offset seen in the circumferential direction of the platform connection relative to the blade connection EBdist can be 0.70 . . . 1.35*tmax0, where ABdist is greater than EBdist.

A further aspect of the present disclosure relates to a blisk in a gas turbine comprising at least one blade having a blade airfoil and a blade root, a platform, in particular a rotor disk platform, the blade being integrally attached to the platform, a fillet connecting the blade to the platform at the blade root and between the blade airfoil and the platform. The fillet extends with a longitudinal extent around the blade root and a transverse extent from the platform to the blade airfoil, the fillet having a variable radius along the transverse extent. An aspect of the present disclosure further provides for this further blade-platform connection such that the fillet has a, in particular structural and/or geometric, decoupling means for static and dynamic stresses occurring in the blade-platform connection during operation.

FIG.1shows a perspective view of a segment of an exemplary embodiment of a blisk2according to the present disclosure. The blisk2is arranged in a gas turbine1for an aircraft engine, whereby the gas turbine1is indicated inFIG.1by its three main axes Ax, R, U. The three main axes run in the axial direction Ax, radial direction R and circumferential direction U. The three main axes run in the axial direction Ax, radial direction R and circumferential direction U. The blisk2serves as a rotor in a compressor of the gas turbine1.

The blisk2comprises a blisk disk4and a plurality of blades10, referred to as rotor blades, arranged on the blisk disk4. The blades10are arranged on a platform surface22of a platform20of the blisk disk4at a distance from one another in the circumferential direction U. The blades10, the platform20and a fillet30connecting one of the blades10and the platform20together form a blade-platform connection3. The blades10have a blade airfoil11for absorbing aerodynamic forces, a blade root14for connection to the platform surface20and a blade tip15pointing towards an annular space wall of the gas turbine1. The blisk2rotates in the circumferential direction U, whereby a suction side16of the respective blade10is arranged against the direction of rotation and a pressure side17of the respective blade10is arranged in the direction of rotation of the blisk2. The suction and pressure sides16and17each extend from a leading edge12to a trailing edge13of the respective blade10.

The blisks2have a particularly robust crack growth behavior, whereby cracks can hardly or not at all penetrate into the disk, but the blades10are separated from the platform20beforehand.

The blade-platform connections3are explained in more detail below with reference to two exemplary embodiments inFIGS.2a,2bandFIGS.3a,3b.

FIG.2ashows a first exemplary embodiment of a blade-platform connection3according to the present disclosure in a spatial, schematic representation on a suction side16of a blade10. The blade-platform connection3comprises the blade10, a platform20and a fillet30that connects the blade10and the platform20to one another. As described inFIG.1, the blade10has a blade airfoil11and a blade root14. The fillet30surrounds the blade root14along its longitudinal extent L and extends transversely to its longitudinal extent L along its transverse extent Q from the platform20to the blade airfoil11.

In the exemplary embodiment, the fillet30extends around and from a leading edge12to a trailing edge13of the blade10, a longitudinal extent L of the fillet30being defined in each case from the leading edge12to the trailing edge13. In this exemplary embodiment, the trailing edge13is formed by a cut of the blisk2, so that the blade10has two trailing edges13in a region of the blade root14, which converge at the blade airfoil11. The fillet30therefore ends at the trailing edges13and does not encircle them. The fillet30adjoins the blade10and/or the blade airfoil11with a blade connection32and adjoins the platform20with a platform connection34. In transverse extent Q, the fillet30is concave over the entire longitudinal extent L and has a variable radius r.

The variable radius r is a minimum radius rminin a central region38of the fillet30along the transverse extent Q. In practical terms, the longitudinal extent L is measured at the height of the minimum radius Rminof the fillet. The central region38is band-shaped and extends around the blade10, whereby the minimum radius rmincan extend at one point over a part or the entire width of the central region38. In this way, a surface can be formed that has the minimum radius. The central region38is spaced from the blade connection32by at least 20%, 25% or 30% of the transverse extent Q of the fillet30. Furthermore, the central region38is spaced from the platform connection34by at least 30% of the transverse extent Q of the fillet30. In the longitudinal extent L of the fillet30, the minimum radius rminis spaced from the front edge12by at least 5%, 10%, 15%, 20%, 25% or 30% of the longitudinal extent L of the fillet30. Furthermore, the minimum radius rminis at least 10%, 15%, 20%, 25% or 30% of the longitudinal extent L of the fillet30from the trailing edge13.

As a result, the minimum radius rminis advantageously arranged in a central area of the fillet30on the suction side16of the blade10. This enables the targeted separation of static and dynamic stress maxima and is therefore beneficial for the damage tolerance of the component.

FIG.2bshows the first exemplary embodiment of the blade-platform connection3according to the present disclosure illustrated with exemplary radii r. For the sake of clarity, not all reference numerals are shown again.

In the present exemplary embodiment, the variable radii r have a maximum radius rmaxalong the longitudinal extent L in all cases on the outside and inside at the blade transition32and at the platform transition34. In combination with the minimum radius rminin the central region38, this results in a trough-shaped or U-shaped transverse extent of the fillet30along its longitudinal extent L.

BothFIG.2aandFIG.2bshow a first section36aof the fillet30, which can have the above-mentioned properties. In particular, at a maximum point M, a ratio of the larger maximum radius rmaxto the minimum radius rmincan be maximum. The maximum point M may be spaced at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% from the leading edge12and/or the trailing edge13projected onto a chord S of the blade10at the radial height of the maximum point M. It may be provided that the first section36ais arranged at a position of the fillet30, which has the smallest distance to an adjacent blade10on the blisk2.

In the first exemplary embodiment inFIGS.2aand2b, the ratio of the maximum radius rmaxto the minimum radius rmaxdecreases along the longitudinal extent L in the direction of the leading edge12and the trailing edge13. In the present exemplary embodiment, the trough shape or the U-shape is retained between the leading edge12and the trailing edge13of the blade, but is no longer as pronounced at the leading edge12and the trailing edge13, so that a better flow of force can advantageously take place in the front region and the rear region of the blade10. In order to achieve this progression, at least one of the two maximum radii rmaxcan, for example, decrease in the direction of the leading edge and/or the trailing edge, and in particular decrease monotonically. Alternatively or additionally, it is also possible for the minimum radius rminto increase in the direction of the leading edge12and/or the trailing edge13.

The exemplary embodiment shown avoids further stress concentrations in areas subject to high static loads, for example in the fillet between the blade and platform, by introducing a larger radius.

FIGS.3aand3bshow a second exemplary embodiment of a blade-platform connection3according to the present disclosure in a spatial, schematic representation on a suction side16of a blade10. Only differences to the first exemplary embodiment are described below. Further details and differences to the first exemplary embodiment may arise from the figures.

On the pressure side17of the blade10, a first section36ahaving the characteristics described above with respect to the first exemplary embodiment is arranged in a front region of the blade-platform connection3in spatial proximity to the leading edge12of the blade10. The distance to the leading edge12along the longitudinal extent of the fillet is 20% or less. This means that a maximum ratio between the maximum radius rmaxand the minimum radius rminis arranged in the vicinity of the leading edge12.

A second section36bof the fillet30with properties differing from the first section36ais arranged in a central region along the longitudinal extent L of the fillet30. This second section36bis arranged on the pressure side and has a ratio of the maximum radius rmaxto the minimum radius rminof less than 1.5. Particularly preferably, the radius along the transverse extent Q of the fillet30is constant in the second section36b. The second section36bcan preferably be spaced apart from the leading edge12and/or the trailing edge13by at least 30% of the length of the blade chord, projected onto the blade chord S. This advantageously achieves a uniform radius in the center of the blade in the longitudinal extent L of the fillet30.

It may be provided that a third section36cof the fillet is provided in a rear region of the fillet30in the vicinity of the trailing edge13of the blade10, which is similar to the first section but has a smaller ratio of maximum radius rmaxto minimum radius rmin.

Finally, in a further embodiment example, it may be provided that a fillet30according to the first exemplary embodiment as shown inFIGS.2aand2b, which describes the fillet path on the suction side16of the blade10, and that a fillet30according to the second exemplary embodiment as shown inFIGS.3aand3b, which describes the fillet path on the pressure side17, are combined. Thus, the first section can be arranged at the same height or at a maximum 10% deviation along the chord S of the blade10as the second section36b. This directs crack propagation to one side of the blade, so that the probability of a disk crack is advantageously reduced on the more heavily loaded pressure side17of the blade10.

While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.

The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.

LIST OF REFERENCE NUMERALS

1gas turbine2blisk3blade-platform connection10blade11blade airfoil12leading edge13trailing edge14blade root15blade tip16suction side17pressure side20platform22platform surface30fillet32blade connection34platform connection36afirst section36bsecond section38central regionR variable radiusrminminimum radiusrmaxmaximum radiusS chord bladeM maximum point