EP3976931A1 - Turbine vane provided with a recess for embrittlement of a frangible section - Google Patents

Turbine vane provided with a recess for embrittlement of a frangible section

Info

Publication number
EP3976931A1
EP3976931A1 EP20726420.1A EP20726420A EP3976931A1 EP 3976931 A1 EP3976931 A1 EP 3976931A1 EP 20726420 A EP20726420 A EP 20726420A EP 3976931 A1 EP3976931 A1 EP 3976931A1
Authority
EP
European Patent Office
Prior art keywords
stilt
blade
plane
turbine
cavity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP20726420.1A
Other languages
German (de)
French (fr)
Other versions
EP3976931B1 (en
Inventor
Matthieu Claude Jean DENAUX
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Safran Helicopter Engines SAS
Original Assignee
Safran Helicopter Engines SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Safran Helicopter Engines SAS filed Critical Safran Helicopter Engines SAS
Publication of EP3976931A1 publication Critical patent/EP3976931A1/en
Application granted granted Critical
Publication of EP3976931B1 publication Critical patent/EP3976931B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/30—Fixing blades to rotors; Blade roots ; Blade spacers
    • F01D5/3007—Fixing blades to rotors; Blade roots ; Blade spacers of axial insertion type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/02—Shutting-down responsive to overspeed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/04—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for responsive to undesired position of rotor relative to stator or to breaking-off of a part of the rotor, e.g. indicating such position
    • F01D21/045—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for responsive to undesired position of rotor relative to stator or to breaking-off of a part of the rotor, e.g. indicating such position special arrangements in stators or in rotors dealing with breaking-off of part of rotor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/14—Form or construction
    • F01D5/147—Construction, i.e. structural features, e.g. of weight-saving hollow blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2220/00—Application
    • F05D2220/30—Application in turbines
    • F05D2220/32—Application in turbines in gas turbines
    • F05D2220/321—Application in turbines in gas turbines for a special turbine stage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/20—Three-dimensional
    • F05D2250/29—Three-dimensional machined; miscellaneous
    • F05D2250/294—Three-dimensional machined; miscellaneous grooved
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/70—Shape
    • F05D2250/71—Shape curved
    • F05D2250/712—Shape curved concave
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/94—Functionality given by mechanical stress related aspects such as low cycle fatigue [LCF] of high cycle fatigue [HCF]
    • F05D2260/941—Functionality given by mechanical stress related aspects such as low cycle fatigue [LCF] of high cycle fatigue [HCF] particularly aimed at mechanical or thermal stress reduction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2270/00—Control
    • F05D2270/01—Purpose of the control system
    • F05D2270/02—Purpose of the control system to control rotational speed (n)
    • F05D2270/021—Purpose of the control system to control rotational speed (n) to prevent overspeed

Definitions

  • the present invention relates to the turbine blades of a turbomachine and, in particular, to a stilt arrangement of a turbine blade.
  • the vane stilt is a supporting portion of the vane blade that extends radially between a lower attachment portion of the vane called a "fir tree" and a vane platform.
  • the invention relates to the turbine blades of a free-turbine turbomachine.
  • the invention also relates to a turbomachine comprising such blades.
  • a free-turbine turbomachine comprises a gas generator 1, comprising at least one compressor which comprises one or more compression stages 2, a combustion chamber 3, and a turbine in which the Hot gases under pressure from the combustion chamber expand and in which the kinetic and thermal energy of the gases is transformed into mechanical energy to drive in rotation a shaft which connects the turbine to the compressor, in order also to drive the compressor.
  • a turbine 4 called a free turbine, which comprises one or more turbine stages, is arranged downstream of the turbine of the gas generator 1, and mechanically decoupled from the latter. The free turbine 4 is driven in rotation by the gases from the gas generator 1.
  • the free turbine In free turbine engines, used for example, but not exclusively, in helicopter propulsion units, the free turbine is mechanically independent of the helicopter rotor, a reduction gear being interposed between the shaft line and the rotor main .
  • the turbine may be in a overspeed situation due to the disappearance of the resistive torque applied to the turbine blades.
  • the stilt 4 of the blade which extends between the base of the fir tree 6 and a platform which forms the base of a profile aerodynamic 5 or blade of the vane, has a concave leading edge 7 making it possible to form in the stilt a frangible zone of minimum section capable of allowing the vane to detach from the disc from a threshold speed protection.
  • FIG. 4 shows the radial stress which is applied in the stanchion of the blade under the effect of thermomechanical forces.
  • the creation of a concave leading edge 7 locally reducing the cross section of the stilt generates the appearance of a zone Z of maximum stress on the leading edge, in the corners of the reduced cross section. .
  • This increase in maximum stress is accompanied by the appearance of an additional moment due to the off-center of the airfoil from the minimum section of the neck of the stilt.
  • the invention aims to provide a turbine blade provided with a frangible section making it possible to adjust the breaking speed value of the blade without increasing the maximum stress in the blade.
  • the object of the invention is therefore a turbine blade comprising a blade and a root, the root comprising a stilt having lateral flanks with a curvilinear profile, said stilt comprising a frangible zone adapted to undergo a rupture of the stilt if radial forces greater than a threshold are exerted on the blade, in particular centrifugal forces during a state of overspeed of the turbine.
  • the frangible zone comprises at least one oblong frangibility cavity formed on at least one of the lateral flanks of the stilt, said oblong cavity extending in an axial direction of the stilt along a longitudinal axis parallel to or included in a plane of minimum section in which there is a minimum cross section of the stilt.
  • This cavity thus makes it possible to weaken the frangible section of the stilt by increasing the average stress exerted in the neck of the stilt, without significantly increasing the maximum stress generated locally under the action of thermomechanical forces. It therefore makes it possible to optimize the setting of the limiting speed from which the blades break.
  • the blade is mounted on a disc, the longitudinal axis of the or each oblong cavity being included in a frangibility plane located at a distance from an axis of rotation of the disc between h + 0.06h and h- 0.06h, preferably between h + 0.04h and h-0.04h, h denoting the distance between the axis of rotation and the plane of minimum section, the plane of frangibility and the plane of minimum section being parallel between them and the axis of rotation.
  • the frangible zone of the stilt is formed by a concave zone of the stilt made on a front face and on at least one of the lateral flanks of the stilt, the most deep of the oblong cavity being intersected by the minimum section plane of the stilt.
  • the maximum depth of the oblong cavity is between 9% and 35% of the width of P stilt, preferably between 10% and 25% of the width of P stilt, considered at the deepest point of the cavity.
  • the maximum depth of the oblong cavity is between 10% and 25% of its length, preferably between 14% and 20% of the length of the cavity.
  • the stilt comprises an oblong frangibility cavity, the distance between the barycenter of the cavities and the projection of the center of gravity of the vane on the plane of minimum section is between 0 and 20% of the axial length of the stilt, of preferably between 0 and 15% of said width of P stilts.
  • the oblong cavity has a curvilinear cross section.
  • the oblong cavity has a cross section in an arc of a circle.
  • the object of the invention is also a turbomachine turbine, comprising a rotor comprising at least one disk and a set of turbine blades mounted on the disc, each blade being a blade as defined above.
  • the longitudinal axis of the or each oblong cavity of each blade is included in a frangibility plane located at a distance from an axis of rotation of the disc between h + 0.06h and h-0.06h, preferably between h + 0.04h and h-0.04h, h denoting the distance between the axis of rotation of the disc and the minimum section plane, the frangibility plane and the minimum section plane being parallel to each other and to l 'rotation axis.
  • FIG 1 illustrates the general structure of a free turbine gas turbine according to the state of the art
  • FIG 3 are respectively front and perspective views of a blade according to the state of the art
  • FIG 4 shows the stress field exerted on the dawn stilt in Figures 2 and 3;
  • FIG 6 are respectively front and perspective views of a blade according to the invention.
  • FIG 7 is a detail view on a larger scale of the blade of Figure 6;
  • FIG 8 is a cross sectional view of the vane stilt of Figures 5 and 6 at the deepest point of the cavities;
  • FIG 9 shows the blade of Figures 5 and 6 mounted on a rotor disc
  • FIG 10 is a perspective view of Fig 8.
  • FIG 1 1 shows the stress field exerted on the blade stilt of Figures 5 and 6.
  • This blade 10 comprises a blade 11, a fir tree root 12 intended for fixing the blade to a rotor disc, by engagement of the root 12 in a housing also called a "cell" of corresponding shape made in the disc, a stilt 13 extending the base of the tree 12 and a platform 14.
  • the fir tree base extends along a longitudinal axis, which in a manner known per se can form an angle with the axis of rotation AA 'of the turbine disk, in order to increase the contact length between the fir tree base and the disc.
  • the axis of the tree base once the dawn has risen on the disc extends in the direction of the corresponding cell in the disc.
  • the cells of a free turbine disk can each be provided more or less obliquely in a plane tangential to the disk, relative to the axial direction of the disk. In other words, an angle in a plane tangential to the disc is formed between the direction of a cell and the axis of the disc.
  • the stilt 13 has a curvilinear shape.
  • the blade 10 furthermore comprises oblong cavities 17, that is to say having a longitudinal dimension greater than their lateral dimension, which are formed in the lateral sides of the stilt 13.
  • Each cavity 17 extends along an axis longitudinal X-X 'parallel or substantially parallel to the longitudinal axis of the fir tree base.
  • the X-X ’axis of each cavity can therefore, like the axis of the tree base, form an angle with the axis of rotation A-A’ of the turbine disk, shown in Figure 9.
  • Each cavity constitutes a pocket locally reducing the cross section of the neck of the stilt in order to weaken the frangible zone of the stilt and to adjust the overspeed limit speed from which the blade detaches from the disc.
  • each lateral flank of the stilt has at least one cavity.
  • Each lateral flank here comprises a cavity, L the stilt comprising a pair of cavities formed symmetrically.
  • each cavity has a concave cross section, considered perpendicular to the longitudinal axis of the cavity, preferably a round cross section, without ridge.
  • the radius R of the cavity is preferably between 10 and 25% of the length of the cavity, advantageously between 14% and 20% of the length of the cavity.
  • Its depth, which may for example correspond to the radius of the cavity, is advantageously between 9% and 35% of the minimum width Imin of the stilt, considered at the level of the deepest point of the cavity (FIG. 8).
  • the depth of the cavity is preferably between 10% and 25% of the width Imin of the stilt.
  • each cavity is made in the concave surface of a lateral flank of the stilt and extends parallel to a longitudinal plane P which coincides with the minimum width of the stilt neck.
  • the axis X-X' of each cavity is included in a plane, hereinafter referred to as the frangibility plane, which either coincides with the plane P, or is parallel to the plane P and is located slightly above or above the plane P. More precisely, the plane of frangibility is located at a distance from the axis of rotation A-A 'of the disc between h-0.06h and h + 0.06h, preferably between h-0.04h and h + 0.04h. Moreover, if the stilt includes a pair of cavities formed symmetrically, the frangibility plane includes the two respective X-X ’axes of the two cavities.
  • the distance d between the barycenter B of all the cavities and the radial projection of the center of gravity G of the blade on the cutting plane is comprised between 0 and 20% of the axial length L of the stilt at the location of its minimum section, preferably between 0 and 15% of this length L
  • the axial length L is measured in a direction parallel to the axis of the fir tree base, which can advantageously form an angle with the axis of rotation A-A ′ of the disk of the turbine. This angle is for example between 5 ° and 20 °.
  • the length of the cavities is for example about 40% of the total length of the base of the fir tree at the location of the minimum section and their depth is about 20% of the width of the neck.
  • Each lateral flank of the stilt may include any number of cavities in order to locally reduce the cross section of the stilt and thereby adjust the limit speed of rotation of the blades.
  • the cavities are devoid of sharp angles so as not to induce a concentration of stresses greater than those already induced by the concave shape made in the anterior face, on the leading edge side.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

The invention relates to a turbine vane of a turbine engine which comprises a blade (11) and a root (12), the root comprising a stilt (13) having lateral flanks with a curvilinear profile, said stilt comprising a frangible zone suitable for undergoing a breakage of the stilt if radial forces higher than a threshold are exerted on the vane, in particular centrifugal forces during an overspeed state of the turbine. The frangible zone comprises at least one oblong frangibility recess (17) formed on at least one of the lateral flanks of the stilt, said oblong recess extending in an axial direction of the stilt along a longitudinal axis (X-X') parallel to or included in a minimum cross-sectional plane (P) which contains a minimum cross-section of the stilt.

Description

DE SCRIPTION OF SCRIPTION
TITRE : Aube de turbine dotée d’une cavité de fragilisation d’une section frangible Domaine technique de l’invention TITLE: Turbine blade with an embrittlement cavity with a frangible section Technical field of the invention
La présente invention concerne les aubes de turbine d’une turbomachine et, en particulier, un agencement d’échasse d’une aube de turbine. L’échasse d’une aube est une partie de support de la pale de l’aube qui s’étend radialement entre une partie d’attache inférieure de l’aube appelée "pied de sapin" et une plateforme de l’aube. The present invention relates to the turbine blades of a turbomachine and, in particular, to a stilt arrangement of a turbine blade. The vane stilt is a supporting portion of the vane blade that extends radially between a lower attachment portion of the vane called a "fir tree" and a vane platform.
Plus particulièrement, l’invention concerne les aubes de turbine d’une turbomachine à turbine libre. More particularly, the invention relates to the turbine blades of a free-turbine turbomachine.
L’invention concerne également une turbomachine comprenant de telles aubes. The invention also relates to a turbomachine comprising such blades.
Etat de la technique antérieur State of the prior art
Classiquement, tel qu’illustré à la figure 1 , une turbomachine à turbine libre comporte un générateur de gaz 1 , comprenant au moins un compresseur qui comporte un ou plusieurs étages de compression 2, une chambre de combustion 3 , et une turbine dans laquelle les gaz chauds sous pression issus de la chambre de combustion se détendent et dans laquelle l’énergie cinétique et thermique des gaz est transformée en énergie mécanique pour entraîner en rotation un arbre qui relie la turbine au compresseur, afin d’entraîner aussi le compresseur. Une turbine 4, dite turbine libre, qui comporte un ou plusieurs étages de turbine, est disposée en aval de la turbine du générateur de gaz 1 , et découplée mécaniquement de cette dernière. La turbine libre 4 est entraînée en rotation par les gaz issus du générateur de gaz 1 . Conventionally, as illustrated in FIG. 1, a free-turbine turbomachine comprises a gas generator 1, comprising at least one compressor which comprises one or more compression stages 2, a combustion chamber 3, and a turbine in which the Hot gases under pressure from the combustion chamber expand and in which the kinetic and thermal energy of the gases is transformed into mechanical energy to drive in rotation a shaft which connects the turbine to the compressor, in order also to drive the compressor. A turbine 4, called a free turbine, which comprises one or more turbine stages, is arranged downstream of the turbine of the gas generator 1, and mechanically decoupled from the latter. The free turbine 4 is driven in rotation by the gases from the gas generator 1.
Dans les turbomoteurs à turbine libre, utilisés par exemple, mais non exclusivement, dans les ensembles propul sifs d’hélicoptère, la turbine libre est mécaniquement indépendante du rotor de l’hélicoptère, un réducteur étant interposé entre la ligne d’arbre et le rotor principal . In free turbine engines, used for example, but not exclusively, in helicopter propulsion units, the free turbine is mechanically independent of the helicopter rotor, a reduction gear being interposed between the shaft line and the rotor main .
En cas de rupture de la ligne de transmi ssion de puissance, par exemple en cas de rupture de la ligne d’arbre ou de la ligne de transmission reliée au réducteur, la turbine peut se trouver dans une situation de survitesse en raison de la disparition du couple résistif qui s’applique sur les aubes de la turbine. In the event of a break in the power transmission line, for example in the event of a break in the shaft line or the transmission line connected to the reducer, the turbine may be in a overspeed situation due to the disappearance of the resistive torque applied to the turbine blades.
Cette situation de survitesse peut être particulièrement dangereuse, conduire à la rupture d'au moins un di sque tournant qui supporte les aubes d'un étage de la turbine, sous l’effet de la force centrifuge, et provoquer la libération de débri s à très haute énergie qui ne peuvent être contenus par le blindage prévu sur le moteur. This overspeed situation can be particularly dangerous, lead to the rupture of at least one rotating di sque which supports the blades of one stage of the turbine, under the effect of centrifugal force, and cause the release of debris to the turbine. very high energy which cannot be contained by the shielding provided on the motor.
Il est donc nécessaire de prévoir dans les turbines des systèmes de protection qui empêchent la survitesse. It is therefore necessary to provide protection systems in the turbines which prevent overspeeding.
II a déj à été proposé, dans l’état de la technique, des systèmes de protection contre la survitesse, connus sous le nom de « blade- shedding » dans la terminologie anglo-saxone, qui consistent à créer dans les aubes une zone frangible de sorte qu’elles se rompent à une vitesse de rotation prédéterminée évitant tout risque de rupture du disque qui serait causée par les efforts centrifuges. On pourra à cet égard se référer au document GB 881 , 850 qui décrit une turbine destinée à l’entrainement d’accessoires dans laquelle des perçages sont pratiqués à la base des pales des aubes. It has already been proposed, in the state of the art, protection systems against overspeed, known under the name of “blade-shedding” in English terminology, which consist in creating a frangible zone in the blades. so that they break at a predetermined speed of rotation avoiding any risk of rupture of the disc which would be caused by centrifugal forces. In this regard, reference may be made to document GB 881, 850 which describes a turbine intended for driving accessories in which bores are made at the base of the blades of the blades.
Ainsi, en cas de risque de survitesse, après rupture des aubes, la turbine, ayant perdu ses profils aérodynamiques, ralentit naturellement, et peut s’arrêter de tourner. Le ralentissement de la turbine libre pour revenir à des vitesses acceptables évite de la sorte le risque d'une rupture du disque causée par les efforts centrifuges. Thus, in the event of a risk of overspeeding, after the blades break, the turbine, having lost its aerodynamic profiles, naturally slows down, and may stop rotating. Slowing down the free turbine to return to acceptable speeds in this way avoids the risk of the disc breaking caused by centrifugal forces.
Il a à cet égard été proposé d’usiner le bord d’attaque du pied de l’aube de la turbine afin d’ajuster la section du col de l’aube pour que celle-ci se rompe à une vitesse souhaitée, tout en conservant une longueur de contact suffisante entre le pied de sapin de l’aube et l’alvéole correspondante du di sque qui reçoit le pied de sapin pour garantir la tenue mécanique de l’attache de l’aube sur le disque. In this regard, it has been proposed to machine the leading edge of the root of the blade of the turbine in order to adjust the section of the neck of the blade so that the latter breaks at a desired speed, while maintaining a sufficient contact length between the base of the blade of the blade and the corresponding cell of the di sque which receives the base of the tree in order to guarantee the mechanical strength of the attachment of the blade to the disc.
On a représenté sur les figures 2 et 3 une aube dotée d’une section frangible destinée à se rompre pour empêcher la survitesse. There is shown in Figures 2 and 3 a blade provided with a frangible section intended to break to prevent overspeed.
Comme on le voit, L échasse 4 de l’aube, qui s’étend entre le pied de sapin 6 et une plateforme qui forme la base d’un profil aérodynamique 5 ou pale de l’aube, comporte un bord d’attaque concave 7 permettant de former dans l’échasse une zone frangible de section minimale apte à permettre à l’aube de se détacher du disque à partir d’une vitesse de seuil de protection. As can be seen, the stilt 4 of the blade, which extends between the base of the fir tree 6 and a platform which forms the base of a profile aerodynamic 5 or blade of the vane, has a concave leading edge 7 making it possible to form in the stilt a frangible zone of minimum section capable of allowing the vane to detach from the disc from a threshold speed protection.
On a représenté sur la figure 4 la contrainte radiale qui s’applique dans l’échasse de l’aube sous l’effet des efforts thermomécaniques. Comme on le voit, la création d’un bord d’attaque concave 7 réduisant localement la section de l’échasse engendre l’apparition d’une zone Z de contrainte maximale sur le bord d’attaque, dans les coins de la section réduite. Cette augmentation de la contrainte maximale s’accompagne de l’apparition d’un moment supplémentaire en raison du décentrage du profil aérodynamique par rapport à la section minimale du col de l’échasse. FIG. 4 shows the radial stress which is applied in the stanchion of the blade under the effect of thermomechanical forces. As can be seen, the creation of a concave leading edge 7 locally reducing the cross section of the stilt generates the appearance of a zone Z of maximum stress on the leading edge, in the corners of the reduced cross section. . This increase in maximum stress is accompanied by the appearance of an additional moment due to the off-center of the airfoil from the minimum section of the neck of the stilt.
Il a été constaté que cette contrainte maximale conditionne la durée de vie en fatigue de l’aube de sorte que la réalisation de cette zone concave dans le bord d’attaque pour fragiliser localement l’aube requiert des travaux de conception relativement complexes afin de définir la valeur de seuil à partir de laquelle les échasses se rompent tout en limitant l’augmentation de la contrainte maximale nui sible à la durée de vie en fatigue de l’aube. It has been observed that this maximum stress conditions the fatigue life of the blade so that the production of this concave zone in the leading edge to locally weaken the blade requires relatively complex design work in order to define the threshold value from which the stilts break while limiting the increase in the maximum stress detrimental to the fatigue life of the blade.
Par ailleurs, l’utilisation de matériaux ayant une résistance accrue pour la réalisation des aubes engendre, pour une même section frangible, une augmentation de la vitesse de seuil à partir de laquelle les échasses se rompent. In addition, the use of materials with increased strength for the production of the blades generates, for the same frangible section, an increase in the threshold speed from which the stilts break.
La réalisation d’une zone concave de dimensions accrues dans le bord d’attaque de l’aube de manière à diminuer localement la section de l’échasse de l’aube ne permettrait pas de réduire la valeur de vitesse limite de rupture de l’échasse sans augmenter de manière rédhibitoire la contrainte maximale sur la section minimale de l’échasse et en conséquence réduire la durée de vie en fatigue de l’aube. Il est donc souhaitable de pouvoir réduire la valeur de vitesse de rupture de l’échasse lorsque l’on utilise un matériau de résistance accrue pour la réalisation de l’aube. Exposé de l’invention The production of a concave zone of increased dimensions in the leading edge of the blade so as to locally reduce the section of the blade stilts would not make it possible to reduce the breaking limit speed value of the blade. stilt without increasing the maximum stress on the minimum cross-section of the stilt in a crippling manner and consequently reducing the fatigue life of the blade. It is therefore desirable to be able to reduce the breaking speed value of the stilt when using a material of increased strength for the production of the blade. Disclosure of the invention
Au vu de ce qui précède, l’invention vise à proposer une aube de turbine dotée d’une section frangible permettant de régler la valeur de vitesse de rupture de l’aube sans augmentation de la contrainte maximale dans l’aube. In view of the above, the invention aims to provide a turbine blade provided with a frangible section making it possible to adjust the breaking speed value of the blade without increasing the maximum stress in the blade.
L’invention a donc pour obj et une aube de turbine comprenant une pale et un pied, le pied comprenant une échasse présentant des flancs latéraux à profil curviligne, ladite échasse comprenant une zone frangible adaptée pour subir une rupture de L échasse si des efforts radiaux supérieurs à un seuil sont exercés sur l’aube, en particuler des efforts centrifuges lors d’un état de survitesse de la turbine. The object of the invention is therefore a turbine blade comprising a blade and a root, the root comprising a stilt having lateral flanks with a curvilinear profile, said stilt comprising a frangible zone adapted to undergo a rupture of the stilt if radial forces greater than a threshold are exerted on the blade, in particular centrifugal forces during a state of overspeed of the turbine.
La zone frangible comprend au moins une cavité oblongue de frangibilité pratiquée sur au moins l’un des flancs latéraux de L échasse, ladite cavité oblongue s’étendant dans une direction axiale de L échasse selon un axe longitudinal parallèle à ou compris dans un plan de section minimale dans lequel se situe une section transversale minimale de L échasse. The frangible zone comprises at least one oblong frangibility cavity formed on at least one of the lateral flanks of the stilt, said oblong cavity extending in an axial direction of the stilt along a longitudinal axis parallel to or included in a plane of minimum section in which there is a minimum cross section of the stilt.
Cette cavité permet ainsi de fragili ser la section frangible de L échasse en augmentant la contrainte moyenne qui s’exerce dans le col de L échasse, sans augmenter de manière significative la contrainte maximale engendrée localement sous l’action des efforts thermomécaniques. Elle permet par conséquent d’optimiser le réglage de la vitesse limite à partir de laquelle les aubes se rompent. This cavity thus makes it possible to weaken the frangible section of the stilt by increasing the average stress exerted in the neck of the stilt, without significantly increasing the maximum stress generated locally under the action of thermomechanical forces. It therefore makes it possible to optimize the setting of the limiting speed from which the blades break.
Avantageusement, l’aube est montée sur un disque, l’axe longitudinal de la ou chaque cavité oblongue étant compris dans un plan de frangibilité situé à une distance d’un axe de rotation du disque comprise entre h+0,06h et h-0,06h, de préférence comprise entre h+0,04h et h-0,04h, h désignant la distance entre l’axe de rotation et le plan de section minimale, le plan de frangibilité et le plan de section minimale étant parallèles entre eux et à l’axe de rotation. Advantageously, the blade is mounted on a disc, the longitudinal axis of the or each oblong cavity being included in a frangibility plane located at a distance from an axis of rotation of the disc between h + 0.06h and h- 0.06h, preferably between h + 0.04h and h-0.04h, h denoting the distance between the axis of rotation and the plane of minimum section, the plane of frangibility and the plane of minimum section being parallel between them and the axis of rotation.
Selon une autre caractéri stique, la zone frangible de L échasse est formée par une zone concave de L échasse réalisée sur une face avant et sur au moins Lun des flancs latéraux de L échasse, la zone la plus profonde de la cavité oblongue étant intersectée par le plan de section minimale de r échasse. According to another characteristic, the frangible zone of the stilt is formed by a concave zone of the stilt made on a front face and on at least one of the lateral flanks of the stilt, the most deep of the oblong cavity being intersected by the minimum section plane of the stilt.
Par exemple, la profondeur maximale de la cavité oblongue est comprise entre 9% et 35% de la largeur de P échasse, de préférence comprise entre 10% et 25% de la largeur de P échasse, considérée à l’endroit le plus profond de la cavité. For example, the maximum depth of the oblong cavity is between 9% and 35% of the width of P stilt, preferably between 10% and 25% of the width of P stilt, considered at the deepest point of the cavity.
Dans un mode de réalisation, la profondeur maximale de la cavité oblongue est comprise entre 10% et 25% de sa longueur, de préférence comprise entre 14% et 20% de la longueur de la cavité In one embodiment, the maximum depth of the oblong cavity is between 10% and 25% of its length, preferably between 14% and 20% of the length of the cavity.
Dans un mode de réalisation, dans lequel chaque flanc latéral de In one embodiment, in which each side flank of
P échasse comprend une cavité oblongue de frangibilité, la distance entre le barycentre des cavités et la proj ection du centre de gravité de l’aube sur le plan de section minimale est compris entre 0 et 20% de la longueur axiale de P échasse, de préférence entre 0 et 15% de ladite largeur de P échasse. The stilt comprises an oblong frangibility cavity, the distance between the barycenter of the cavities and the projection of the center of gravity of the vane on the plane of minimum section is between 0 and 20% of the axial length of the stilt, of preferably between 0 and 15% of said width of P stilts.
Avantageusement, la cavité oblongue comporte une section transversale curviligne. Advantageously, the oblong cavity has a curvilinear cross section.
De préférence, la cavité oblongue comporte une section transversale en arc de cercle. Preferably, the oblong cavity has a cross section in an arc of a circle.
L’invention a également pour obj et une turbine de turbomachine, comprenant un rotor comportant au moins un disque et un ensemble d’aubes de turbine montées sur le disque, chaque aube étant une aube telle que définie ci-dessus. The object of the invention is also a turbomachine turbine, comprising a rotor comprising at least one disk and a set of turbine blades mounted on the disc, each blade being a blade as defined above.
Avantageusement, l’axe longitudinal de la ou chaque cavité oblongue de chaque aube est compris dans un plan de frangibilité situé à une distance d’un axe de rotation du disque comprise entre h+0,06h et h-0,06h, de préférence comprise entre h+0,04h et h-0,04h, h désignant la distance entre l’axe de rotation du disque et le plan de section minimal, le plan de frangibilité et le plan de section minimale étant parallèles entre eux et à l’axe de rotation. Advantageously, the longitudinal axis of the or each oblong cavity of each blade is included in a frangibility plane located at a distance from an axis of rotation of the disc between h + 0.06h and h-0.06h, preferably between h + 0.04h and h-0.04h, h denoting the distance between the axis of rotation of the disc and the minimum section plane, the frangibility plane and the minimum section plane being parallel to each other and to l 'rotation axis.
D’autres buts, caractéristiques et avantages de l’invention apparaîtront à la lecture de la description suivante, donnée uniquement à titre d’exemple, et faite en référence aux dessins annexés. Brève description des dessins Other objects, characteristics and advantages of the invention will become apparent on reading the following description, given solely by way of example, and made with reference to the appended drawings. Brief description of the drawings
[Fig 1 ], dont il a déj à été fait mention, illustre la structure générale d’une turbine à gaz à turbine libre selon l’état de la technique ; [Fig 1], which has already been mentioned, illustrates the general structure of a free turbine gas turbine according to the state of the art;
[Fig 2] [Fig 2]
[Fig 3 ], déj à évoquées, sont respectivement des vues de face et en perspective d’une aube selon l’état de la technique ; [Fig 3], already mentioned, are respectively front and perspective views of a blade according to the state of the art;
[Fig 4] dont il a déj à été fait mention, montre le champ de contraintes s’exerçant sur l’échasse de l’aube des figures 2 et 3 ; [Fig 4], which has already been mentioned, shows the stress field exerted on the dawn stilt in Figures 2 and 3;
[Fig 5] [Fig 5]
[Fig 6] sont respectivement des vues de face et en perspective d’une aube selon l’invention ; [Fig 6] are respectively front and perspective views of a blade according to the invention;
[Fig 7] est une vue de détail à plus grande échelle de l’aube de la figure 6 ; [Fig 7] is a detail view on a larger scale of the blade of Figure 6;
[Fig 8] est une vue en coupe transversale de l’échasse de l’aube des figures 5 et 6 à l’endroit le plus profond des cavités ; [Fig 8] is a cross sectional view of the vane stilt of Figures 5 and 6 at the deepest point of the cavities;
[Fig 9] montre l’aube des figures 5 et 6 montée sur un disque de rotor ; [Fig 9] shows the blade of Figures 5 and 6 mounted on a rotor disc;
[Fig 10] est une vue en perspective de la figure 8 ; et [Fig 10] is a perspective view of Fig 8; and
[Fig 1 1 ] montre le champ de contraintes s’exerçant sur l’échasse de l’aube des figures 5 et 6. [Fig 1 1] shows the stress field exerted on the blade stilt of Figures 5 and 6.
Exposé détaillé d’au moins un mode de réalisation Detailed description of at least one embodiment
On a représenté sur les figures 5 et 6 une aube de turbomachine, en particulier une aube de turbine libre, désignée par la référence numérique générale 10. There is shown in Figures 5 and 6 a turbine engine blade, in particular a free turbine blade, designated by the general reference numeral 10.
Cette aube 10 comporte une pale 1 1 , un pied de sapin 12 destiné à la fixation de l’aube sur un disque de rotor, par engagement du pied 12 dans un logement aussi appelé « alvéole » de forme correspondante pratiqué dans le disque, une échasse 13 prolongeant le pied de sapin 12 et une plateforme 14. This blade 10 comprises a blade 11, a fir tree root 12 intended for fixing the blade to a rotor disc, by engagement of the root 12 in a housing also called a "cell" of corresponding shape made in the disc, a stilt 13 extending the base of the tree 12 and a platform 14.
Le pied de sapin s’étend selon un axe longitudinal, qui de façon connue en soi peut former un angle avec l’axe de rotation A-A’ du disque de la turbine, afin d’augmenter la longueur de contact entre le pied de sapin et le disque. L’axe du pied de sapin une fois l’aube montée sur le disque s’étend selon la direction de l’alvéole correspondante dans le disque. Les alvéoles d’un di sque de turbine libre peuvent être prévues chacune plus ou moins en oblique dans un plan tangentiel au di sque, par rapport à la direction axiale du disque. En d’autres termes un angle dans un plan tangentiel au disque est formé entre la direction d’une alvéole et l’axe du di sque. The fir tree base extends along a longitudinal axis, which in a manner known per se can form an angle with the axis of rotation AA 'of the turbine disk, in order to increase the contact length between the fir tree base and the disc. The axis of the tree base once the dawn has risen on the disc extends in the direction of the corresponding cell in the disc. The cells of a free turbine disk can each be provided more or less obliquely in a plane tangential to the disk, relative to the axial direction of the disk. In other words, an angle in a plane tangential to the disc is formed between the direction of a cell and the axis of the disc.
Comme on le voit, L échasse 13 a une forme curviligne. As can be seen, the stilt 13 has a curvilinear shape.
Elle comporte, sur sa face antérieure, du côté du bord d’attaque de l’aube, une forme concave 1 5 et des flancs latéraux 16 également concaves afin de réduire localement la section de L échasse pour délimiter une zone frangible dans L échasse. It comprises, on its front face, on the side of the leading edge of the blade, a concave shape 1 5 and lateral flanks 16 also concave in order to locally reduce the section of the stilt to define a frangible zone in the stilt.
L’aube 10 comporte par ailleurs des cavités 17 oblongues, c’est- à-dire présentant une dimension longitudinale supérieure à leur dimension latérale, qui sont pratiquées dans les flancs latéraux de L échasse 13. Chaque cavité 17 s’étend selon un axe longitudinal X- X’parallèle ou sensiblement parallèle à l’axe longitudinal du pied de sapin. L’axe X-X’ de chaque cavité peut donc, comme l’axe du pied de sapin, former un angle avec l’axe de rotation A-A’ du disque de la turbine, visible sur la figure 9. The blade 10 furthermore comprises oblong cavities 17, that is to say having a longitudinal dimension greater than their lateral dimension, which are formed in the lateral sides of the stilt 13. Each cavity 17 extends along an axis longitudinal X-X 'parallel or substantially parallel to the longitudinal axis of the fir tree base. The X-X ’axis of each cavity can therefore, like the axis of the tree base, form an angle with the axis of rotation A-A’ of the turbine disk, shown in Figure 9.
Chaque cavité constitue une poche réduisant localement la section transversale du col de L échasse afin de fragiliser la zone frangible de L échasse et de régler la vitesse limite de survitesse à partir de laquelle la pale se détache du disque. Each cavity constitutes a pocket locally reducing the cross section of the neck of the stilt in order to weaken the frangible zone of the stilt and to adjust the overspeed limit speed from which the blade detaches from the disc.
Par exemple, tel qu’illustré, chaque flanc latéral de L échasse comporte au moins une cavité. Chaque flanc latéral comporte ici une cavité, L échasse comprenant une paire de cavités pratiquées de manière symétrique. For example, as illustrated, each lateral flank of the stilt has at least one cavity. Each lateral flank here comprises a cavity, L the stilt comprising a pair of cavities formed symmetrically.
Tel qu’illustré sur la figure 7, chaque cavité comporte une section transversale concave, considérée perpendiculairement à l’axe longitudinal de la cavité, de préférence une section transversale ronde, sans arête. Le rayon R de la cavité est de préférence compris entre 10 et 25% de la longueur de la cavité, avantageusement compri s entre 14% et 20% de la longueur de la cavité. Sa profondeur, qui peut par exemple correspondre au rayon de la cavité, est avantageusement comprise entre 9% et 35% de la largeur minimale Imin de l’échasse, considérée au niveau du point le plus profond de la cavité (figure 8). La profondeur de la cavité est de préférence comprise entre 10% et 25% de la largeur Imin de l’échasse. As illustrated in FIG. 7, each cavity has a concave cross section, considered perpendicular to the longitudinal axis of the cavity, preferably a round cross section, without ridge. The radius R of the cavity is preferably between 10 and 25% of the length of the cavity, advantageously between 14% and 20% of the length of the cavity. Its depth, which may for example correspond to the radius of the cavity, is advantageously between 9% and 35% of the minimum width Imin of the stilt, considered at the level of the deepest point of the cavity (FIG. 8). The depth of the cavity is preferably between 10% and 25% of the width Imin of the stilt.
En référence à la figure 9, qui illustre une aube montée sur une portion d’un disque D, chaque cavité est pratiquée dans la surface concave d’un flanc latéral de l’échasse et s’étend parallèlement à un plan longitudinal P qui coïncide avec la largeur minimale du col de l’échasse. With reference to FIG. 9, which illustrates a blade mounted on a portion of a disc D, each cavity is made in the concave surface of a lateral flank of the stilt and extends parallel to a longitudinal plane P which coincides with the minimum width of the stilt neck.
En considérant la distance h entre l’axe de rotation A-A’ du disque de la turbine et le plan P, l’axe X-X’ de chaque cavité est compri s dans un plan, désigné par la suite plan de frangibilité, qui soit coïncide avec le plan P, soit est parallèle au plan P et se situe légèrement au- dessus ou au-dessus du plan P. Plus précisément, le plan de frangibilité se situe à une distance de l’axe de rotation A-A’ du disque comprise entre h-0,06h et h+0,06h, de préférence comprise entre h-0,04h et h+0,04h. Par ailleurs, si l’échasse comprend une paire de cavités pratiquées de manière symétrique, le plan de frangibilité comprend les deux axes X-X’ respectifs des deux cavités. Considering the distance h between the axis of rotation A-A 'of the turbine disk and the plane P, the axis X-X' of each cavity is included in a plane, hereinafter referred to as the frangibility plane, which either coincides with the plane P, or is parallel to the plane P and is located slightly above or above the plane P. More precisely, the plane of frangibility is located at a distance from the axis of rotation A-A 'of the disc between h-0.06h and h + 0.06h, preferably between h-0.04h and h + 0.04h. Moreover, if the stilt includes a pair of cavities formed symmetrically, the frangibility plane includes the two respective X-X ’axes of the two cavities.
Par ailleurs, comme visible sur la figure 10, qui illustre une vue en perspective et en coupe transversale au niveau des points les plus profonds des cavités, la distance d entre le barycentre B de l’ensemble des cavités et la proj ection radiale du centre de gravité G de l’aube sur le plan de coupe est compri se entre 0 et 20% de la longueur axiale L de l’échasse à l’endroit de sa section minimale, de préférence comprise entre 0 et 15% de cette longueur L. La longueur axiale L est mesurée selon une direction parallèle à l’axe du pied de sapin, lequel peut avantageusement faire un angle avec l’axe de rotation A-A’ du disque de la turbine. Cet angle est compris par exemple entre 5° et 20 ° . Moreover, as visible in Figure 10, which illustrates a perspective view in cross section at the deepest points of the cavities, the distance d between the barycenter B of all the cavities and the radial projection of the center of gravity G of the blade on the cutting plane is comprised between 0 and 20% of the axial length L of the stilt at the location of its minimum section, preferably between 0 and 15% of this length L The axial length L is measured in a direction parallel to the axis of the fir tree base, which can advantageously form an angle with the axis of rotation A-A ′ of the disk of the turbine. This angle is for example between 5 ° and 20 °.
La longueur des cavités est par exemple d’environ 40% de la longueur totale du pied de sapin à l’endroit de la section minimale et leur profondeur est d’environ 20% de la largeur du col . Chaque flanc latéral de l’échasse peut comporter un nombre quelconque de cavités afin de réduire localement la section de P échasse et régler de la sorte la vitesse limite de rotation des aubes. The length of the cavities is for example about 40% of the total length of the base of the fir tree at the location of the minimum section and their depth is about 20% of the width of the neck. Each lateral flank of the stilt may include any number of cavities in order to locally reduce the cross section of the stilt and thereby adjust the limit speed of rotation of the blades.
Comme indiqué précédemment, les cavités sont dépourvues d’angle vif afin de ne pas induire de concentration de contraintes plus fortes que celles qui sont déj à induites par la forme concave pratiquée dans la face antérieure, du côté du bord d’attaque. As previously indicated, the cavities are devoid of sharp angles so as not to induce a concentration of stresses greater than those already induced by the concave shape made in the anterior face, on the leading edge side.
Ces cavités permettent de régler la vitesse de rupture de l’aube en augmentant la contrainte moyenne qui s’exerce dans le col de l’échasse, sans augmenter de manière significative la contrainte maximale engendrée sous l’action des efforts thermomécaniques nuisibles à la durée de vie de l’aube. These cavities make it possible to adjust the breaking speed of the blade by increasing the average stress exerted in the neck of the stilt, without significantly increasing the maximum stress generated under the action of thermomechanical forces detrimental to the duration. of dawn life.
En effet, comme le montre la figure 1 1 , qui illustre le champ de contraintes radiales s’exerçant dans l’aube sous l’action des efforts thermomécaniques, l’introduction d’une cavité dans la zone frangible de l’échasse n’engendre pas d’augmentation significative de la contrainte maximale qui reste localisée dans la zone Z’ du bord de la concavité du bord d’attaque de l’aube. A titre d’exemple, l’introduction d’une cavité oblongue dans chacun des deux flancs latéraux de l’échasse, dans le cas représenté sur cette figure 1 1 , a augmenté localement la contrainte maximale de seulement 1 %. Indeed, as shown in Figure 1 1, which illustrates the radial stress field exerted in the blade under the action of thermomechanical forces, the introduction of a cavity in the frangible zone of the stilt n ' does not generate a significant increase in the maximum stress which remains localized in the zone Z 'of the edge of the concavity of the leading edge of the blade. For example, the introduction of an oblong cavity in each of the two lateral sides of the stilt, in the case shown in this figure 1 1, locally increased the maximum stress by only 1%.

Claims

REVENDICATIONS
1 . Aube ( 10) de turbine d'une turbomachine, comportant une pale (1 1 ) et un pied ( 12), ledit pied comprenant une échasse ( 13) présentant des flancs latéraux à profil curviligne, ladite échasse comprenant une zone frangible adaptée pour subir une rupture de l’échasse si des efforts radiaux supérieurs à un seuil sont exercés sur l’aube, en particuler des efforts centrifuges lors d’un état de survitesse de la turbine, l'aube de turbine étant caractérisée en ce que la zone frangible comprend au moins une cavité oblongue (17) de frangibilité pratiquée sur au moins l’un des flancs latéraux de l’échasse, ladite cavité oblongue s’étendant dans une direction axiale de l’échasse selon un axe longitudinal (X-X’) parallèle à ou compris dans un plan de section minimale (P) dans lequel se situe une section transversale minimale de l’échasse, la zone frangible de l’échasse ( 13) étant formée par une zone concave ( 15) de l’échasse réalisée sur une face avant et sur au moins l’un des flancs latéraux de l’échasse, la zone la plus profonde de la cavité oblongue ( 17) étant intersectée par le plan de section minimale (P) de l’échasse. 1. Turbine blade (10) of a turbomachine, comprising a blade (1 1) and a root (12), said root comprising a stilt (13) having lateral flanks with a curvilinear profile, said stilt comprising a frangible zone adapted to undergo rupture of the stilt if radial forces greater than a threshold are exerted on the blade, in particular centrifugal forces during a state of overspeed of the turbine, the turbine blade being characterized in that the frangible zone comprises at least one oblong cavity (17) of frangibility formed on at least one of the lateral flanks of the stilt, said oblong cavity extending in an axial direction of the stilt along a longitudinal axis (X-X ') parallel to or included in a plane of minimum section (P) in which there is a minimum cross section of the stilt, the frangible zone of the stilt (13) being formed by a concave zone (15) of the stilt produced on a front face and on at least one of the lateral flanks of the stilt, the deepest area of the oblong cavity (17) being intersected by the minimum section plane (P) of the stilt.
2. Aube selon la revendication 1 , montée sur un disque (D) de rotor de turbomachine, dans laquelle l’axe longitudinal (X-X’) de la ou chaque cavité oblongue ( 17) est compris dans un plan de frangibilité situé à une distance d’un axe de rotation (A-A’) du disque (D) comprise entre h+0,06h et h-0,06h, de préférence comprise entre h+0,04h et h- 0,04h, h désignant la distance entre l’axe de rotation (A-A’) et le plan de section minimale (P), le plan de frangibilité et le plan de section minimale (P) étant parallèles entre eux et à l’axe de rotation (A-A’). 2. Blade according to claim 1, mounted on a disk (D) of a turbomachine rotor, in which the longitudinal axis (X-X ') of the or each oblong cavity (17) is included in a frangibility plane located at a distance from an axis of rotation (A-A ') of the disc (D) between h + 0.06h and h-0.06h, preferably between h + 0.04h and h- 0.04h, h denoting the distance between the axis of rotation (A-A ') and the plane of minimum section (P), the plane of frangibility and the plane of minimum section (P) being parallel to each other and to the axis of rotation ( A-A ').
3. Aube selon l’une des revendications 1 et 2, dans laquelle la profondeur maximale (R) de la cavité oblongue ( 17) est comprise entre 9% et 35% de la largeur ( Imin ) de l’échasse, de préférence comprise entre 10% et 25% de la largeur (Imin) de l’échasse, considérée à l’endroit le plus profond de la cavité. 3. Blade according to one of claims 1 and 2, wherein the maximum depth (R) of the oblong cavity (17) is between 9% and 35% of the width (Imin) of the stilt, preferably between between 10% and 25% of the width (Imin) of the stilt, considered at the deepest point of the cavity.
4. Aube selon l’une quelconque des revendications 1 à 3 , dans laquelle la profondeur maximale (R) de la cavité oblongue ( 17) est comprise entre 10% et 25% de sa longueur, de préférence comprise entre 14% et 20% de la longueur de la cavité. 4. Blade according to any one of claims 1 to 3, wherein the maximum depth (R) of the oblong cavity (17) is between 10% and 25% of its length, preferably between 14% and 20%. the length of the cavity.
5. Aube selon l’une quelconque des revendications 1 à 4, dans laquelle chaque flanc latéral de l’échasse comprend une cavité oblongue ( 17) de frangibilité et dans laquelle la distance entre le barycentre (B) des cavités et la proj ection du centre de gravité G de l’aube sur le plan de section minimale (P) est comprise entre 0 et 20% de la longueur axiale (L) de l’échasse, de préférence entre 0 et 15% de ladite longueur de l’échasse. 5. Blade according to any one of claims 1 to 4, wherein each lateral flank of the stilt comprises an oblong cavity (17) of frangibility and in which the distance between the barycenter (B) of the cavities and the projection of the center of gravity G of the blade on the plane of minimum section (P) is between 0 and 20% of the axial length (L) of the stilt, preferably between 0 and 15% of said length of the stilt .
6. Aube selon l’une quelconque des revendications 1 à 5 , dans laquelle la cavité oblongue ( 17) comporte une section transversale curviligne. 6. A blade according to any one of claims 1 to 5, wherein the oblong cavity (17) has a curvilinear cross section.
7. Aube selon l’une quelconque des revendications 1 à 6, dans laquelle la cavité oblongue ( 17) comporte une section transversale en arc de cercle. 7. A blade according to any one of claims 1 to 6, wherein the oblong cavity (17) has a cross section in an arc of a circle.
8. Turbine de turbomachine, comprenant un rotor comportant au moins un disque et un ensemble d’aubes de turbine montées sur le disque, caractéri sée en ce que chaque aube est une aube ( 10) selon l’une quelconque des revendications 1 à 7. 8. Turbomachine turbine, comprising a rotor comprising at least one disc and a set of turbine blades mounted on the disc, characterized in that each blade is a blade (10) according to any one of claims 1 to 7. .
9. Turbine selon la revendication 8, dans laquelle l’axe longitudinal (X-X’) de la ou chaque cavité oblongue ( 17) de chaque aube est compris dans un plan de frangibilité situé à une distance d’un axe de rotation (A-A’) du di sque (D) comprise entre h+0,06h et h-0,06h, de préférence comprise entre h+0,04h et h-0,04h, h désignant la distance entre l’axe de rotation du disque (A-A’) et le plan de section minimale (P), le plan de frangibilité et le plan de section minimale (P) étant parallèles entre eux et à l’axe de rotation (A-A’). 9. Turbine according to claim 8, wherein the longitudinal axis (X-X ') of the or each oblong cavity (17) of each blade is included in a frangibility plane located at a distance from an axis of rotation ( A-A ') of the di sque (D) between h + 0.06h and h-0.06h, preferably between h + 0.04h and h-0.04h, h denoting the distance between the axis of rotation of the disc (A-A ') and the plane of minimum section (P), the plane of frangibility and the plane of minimum section (P) being parallel to each other and to the axis of rotation (A-A').
EP20726420.1A 2019-05-27 2020-05-18 Turbine blade having a fragilization cavity of a frangible section Active EP3976931B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1905588A FR3096727B1 (en) 2019-05-27 2019-05-27 Turbine blade with an embrittlement cavity with a frangible section
PCT/EP2020/063781 WO2020239490A1 (en) 2019-05-27 2020-05-18 Turbine vane provided with a recess for embrittlement of a frangible section

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EP3976931A1 true EP3976931A1 (en) 2022-04-06
EP3976931B1 EP3976931B1 (en) 2023-08-09

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US (1) US11846206B2 (en)
EP (1) EP3976931B1 (en)
CN (1) CN113891983B (en)
CA (1) CA3139054A1 (en)
FR (1) FR3096727B1 (en)
PL (1) PL3976931T3 (en)
WO (1) WO2020239490A1 (en)

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KR20230081267A (en) 2021-11-30 2023-06-07 두산에너빌리티 주식회사 Turbine blade, turbine and gas turbine including the same

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB881850A (en) 1959-05-05 1961-11-08 Gen Electric Improvements in turbine speed limiting arrangement
US5435694A (en) * 1993-11-19 1995-07-25 General Electric Company Stress relieving mount for an axial blade
FR3015553B1 (en) * 2013-12-23 2019-05-31 Safran Aircraft Engines DAWN COMPRISING AN ECHASSE, PROVIDED WITH A SINGLE PORTION IN LOW PRESSURE
US10458257B2 (en) * 2013-12-23 2019-10-29 Safran Aircraft Engines Blade comprising a shank, provided with a depressed portion
FR3025553B1 (en) * 2014-09-08 2019-11-29 Safran Aircraft Engines AUBE A BECQUET AMONT
FR3067625B1 (en) * 2017-06-16 2019-12-27 Safran Aircraft Engines METHOD FOR MANUFACTURING A ROTOR BLADE FOR AN AIRCRAFT TURBOMACHINE
CN109139123B (en) * 2018-08-09 2019-08-23 南京航空航天大学 A kind of method for customizing for flying off fracture position and flying off fracture revolving speed of turbo blade

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US11846206B2 (en) 2023-12-19
PL3976931T3 (en) 2023-12-04
FR3096727B1 (en) 2021-06-25
FR3096727A1 (en) 2020-12-04
US20220235665A1 (en) 2022-07-28
WO2020239490A1 (en) 2020-12-03
CA3139054A1 (en) 2020-12-03
CN113891983B (en) 2023-12-22
CN113891983A (en) 2022-01-04
EP3976931B1 (en) 2023-08-09

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