FR3042812B1 - CENTRAL TUBE OF VENTILATION PRE-CHARGE - Google Patents

CENTRAL TUBE OF VENTILATION PRE-CHARGE Download PDF

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Publication number
FR3042812B1
FR3042812B1 FR1560134A FR1560134A FR3042812B1 FR 3042812 B1 FR3042812 B1 FR 3042812B1 FR 1560134 A FR1560134 A FR 1560134A FR 1560134 A FR1560134 A FR 1560134A FR 3042812 B1 FR3042812 B1 FR 3042812B1
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France
Prior art keywords
support
turbomachine
ventilation tube
central ventilation
tube
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Active
Application number
FR1560134A
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French (fr)
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FR3042812A1 (en
Inventor
Laurent Jean Guibert
Benoit Jean Henri GOMANNE
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Safran Aircraft Engines SAS
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Safran Aircraft Engines SAS
SNECMA SAS
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Priority to FR1560134A priority Critical patent/FR3042812B1/en
Publication of FR3042812A1 publication Critical patent/FR3042812A1/en
Application granted granted Critical
Publication of FR3042812B1 publication Critical patent/FR3042812B1/en
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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
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/18—Lubricating arrangements
    • 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
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/04—Antivibration arrangements
    • 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
    • F05D2240/00—Components
    • F05D2240/60—Shafts
    • F05D2240/61—Hollow
    • 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
    • F05D2260/60—Fluid transfer
    • F05D2260/605—Venting into the ambient atmosphere or the like
    • 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
    • F05D2260/60—Fluid transfer
    • F05D2260/609—Deoiling or demisting

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

Abstract

Support (30) de tube central de ventilation (CVT) de turbomachine débouchant à l'arrière de la turbomachine au niveau d'une tuyère d'éjection (14) à laquelle une première extrémité (16A) de ce support est destinée à être fixé, le support comportant des organes de pré-charge (32) adaptés pour pré-charger le tube central de ventilation en traction et ainsi, en augmentant sa rigidité, repousser sa fréquence propre hors de plages de vibration de ladite turbomachine.Support (30) for a central turbomachine ventilation tube (CVT) opening at the rear of the turbomachine at an ejection nozzle (14) to which a first end (16A) of this support is intended to be fixed , the support comprising pre-load members (32) adapted to pre-load the central ventilation tube in tension and thus, by increasing its rigidity, push its own frequency out of the vibration ranges of said turbomachine.

Description

Arrière-plan de l'invention

La présente invention se rapporte au domaine général des turbomachines et plus particulièrement à l'évacuation d'air huilé de certaines enceintes du moteur.

Classiquement cette évacuation est effectuée par un tube central de ventilation dit CVT pour « Center Vent Tube » qui débouche à l'arrière du moteur par un alésage à l'extrémité de la tuyère d'éjection appelée aussi « plug ». Du fait de la longueur de ce tube (près de 1,5m) et de sa fixation en porte-à-faux au niveau du palier le plus aval de la turbomachine (support du palier arrière rattaché à une structure fixe comme illustré par exemple dans la demande EP1878894), il est prévu un support entre le CVT et le plug.

La figure 2 montre un tel support 10 monté entre le tube central de ventilation 12 et la tuyère d'éjection ou plug 14. Comme illustré, ce support comporte un cône 16 solidaire par une première extrémité 16A avec la tuyère d'éjection et dont une seconde extrémité 16B est prolongée par un élément de guidage 18 reposant sur deux demi-disques 20, 22 enserrant le tube central de ventilation 12 supporté à une extrémité au niveau d'un palier 24 relié à une structure fixe de la turbomachine telle un carter d'échappement et débouchant à une autre extrémité à l'arrière de la turbomachine au niveau du plug 14. Afin d'avoir une situation modale acceptable, c'est-à-dire repousser les modes de flexion des plages de fonctionnement des étages basses et hautes pressions du moteur, le tube présente un diamètre d supérieur à un diamètre minimal dmjn qu'imposerait la seule contrainte de ventilation, ce qui entraîne une augmentation non souhaitée de la masse comme de l'encombrement de ce tube. En effet, le mode propre du tube est donné par l'équation :

Wo = c2/L2*VEI/p*S avec : E : Module d'Young du matériau formant le tube, I : Inertie de la section transversale du tube, S : Section transversale du tube, p; Masse volumique du matériau, L : longueur du tube, et c constante dépendante des conditions aux limites.

Objet et résumé de l'invention

La présente invention a donc pour but de pallier de tels inconvénients en proposant un support amélioré permettant de minimiser l'encombrement et donc la masse du CVT tout en ayant en outre une situation modale acceptable au regard des fréquences moteur. A cet effet, il est prévu un support de tube central de ventilation (CVT) de turbomachine, le tube central de ventilation étant apte à être supporté à une extrémité au niveau d'un palier de ladite turbomachine et débouchant à une autre extrémité à l'arrière de la turbomachine au niveau d'un plug auquel une première extrémité de ce support est destinée à être fixé, caractérisé en ce qu'il comporte des organes de pré-charge adaptés pour pré-charger le tube central de ventilation en traction et ainsi, en augmentant sa rigidité, repousser sa fréquence propre hors des plages de vibration de ladite turbomachine.

En augmentant la fréquence propre du tube du fait de la précharge ainsi constituée, le diamètre du tube peut être réduit à sa dimension minimale admissible. Sa masse s'en trouve réduite d'autant.

Selon le mode de réalisation envisagé, lesdits organes de précharge peuvent consister en un ressort apte à être monté entre une partie radiale d'une seconde extrémité dudit support et un élément d'appui solidaire dudit tube central de ventilation ou bien encore en une ou plusieurs rondelles Belleville aptes à être montée(s) entre une partie radiale d'une seconde extrémité dudit support et un élément d'appui solidaire dudit tube central de ventilation.

De préférence, ledit tube central de ventilation possède un diamètre dmin égal au diamètre minimal admissible pour assurer l'évacuation d'air huilé de la turbomachine. L'invention concerne également une turbomachine comportant un tel support.

Brève description des dessins D’autres caractéristiques et avantages de la présente invention ressortiront de ia description faite ci-dessous, en référence aux dessins annexés qui en illustrent un exemple de réalisation dépourvu de tout caractère limitatif. Sur les figures : - les figures IA et IB sont deux vues en coupe longitudinale d'un tube central de ventilation maintenu par deux moyens alternatifs de support selon l'invention ; et - la figure 2 est une vue en coupe longitudinale d'un tube central de ventilation maintenu par des moyens de support selon l'art antérieur.

Description détaillée de l'invention

La solution technique mise en œuvre pour résoudre le problème précité consiste à pré-charger le tube central de ventilation en traction pour augmenter sa rigidité. Ceci permet de réduire le diamètre du tube et ainsi de gagner de la masse et de limiter l'encombrement de ce tube. L'application d'une pré-charge est effectuée par l'ajout d'organes déformables au niveau du support, comme un ressort (mode de réalisation de la figure IA) ou des rondelles-ressort de type Belleville (mode de réalisation de la figure IB) ou équivalent par exemple.

Ainsi sur la figure IA, le cône 16 du support 30 qui est fixé par une première extrémité 16A au plug 14 se termine à une seconde extrémité par une partie cylindrique 16B entourant à faible distance (pour permettre des dilatations différentielles) le CVT 12 et se terminant elle-même par une partie radiale formant butée 16C. Un ressort agissant en traction 32 est monté entre la butée 16C et un appui radial 12A formé sur le tube central de ventilation 12.

De même sur la figure IB, le cône 16 du support 40 qui est fixé par une première extrémité 16A au plug 14 se termine à une seconde extrémité par une partie cylindrique 16B reposant sur le CVT 12 et se terminant elle-même par une partie radiale formant butée 16C. Deux rondelles Belleville 42 agissant en traction 42 sont montées entre la butée 16C et un appui radial 12A formé sur le tube central de ventilation 12.

Avec cette configuration, la fréquence propre du tube est augmentée du fait de l'effort exercé par ces organes déformables de sorte qu'elle soit repoussée hors de plages connues de fréquences critiques de la turbomachine dépendant essentiellement des régimes de rotation de l'arbre basse pression et du rotor haute pression. En effet, il a été montré par A.Bokaian dans "Naturel frequencies of beams under tensile axiai load" (Journal of Sound and Vibration) que la fréquence propre d'une poutre augmente avec l'effort de pré-contrainte appliqué aux extrémités selon la formule suivante :

Avec : E : Module d'Young du matériau formant la poutre, I : Inertie de la section transversale de la poutre, S : Section transversale de la poutre, p : masse volumique du matériau, L : longueur de la poutre, N : effort de pré-charge, et c et t des constantes dépendantes des conditions aux limites. L'application de ce pré-chargement sur le tube central de ventilation permet ainsi d'en diminuer le diamètre qui dépend essentiellement des distances entre les supports et qui peut alors être égal à dmin diamètre minimal nécessaire pour assurer l'évacuation de l'air huilé.

Background of the invention

The present invention relates to the general field of turbomachines and more particularly to the removal of oil air from certain engine enclosures.

Classically this evacuation is carried out by a central ventilation tube said CVT for "Center Vent Tube" which opens at the rear of the engine by a bore at the end of the ejection nozzle also called "plug". Because of the length of this tube (nearly 1.5m) and its cantilevered attachment at the bearing downstream of the turbomachine (support of the rear bearing attached to a fixed structure as shown for example in application EP1878894), provision is made for a support between the CVT and the plug.

FIG. 2 shows such a support 10 mounted between the central ventilation tube 12 and the ejection nozzle or plug 14. As illustrated, this support comprises a cone 16 secured by a first end 16A with the ejection nozzle and a second end 16B is extended by a guide member 18 resting on two half-disks 20, 22 enclosing the central ventilation tube 12 supported at one end at a bearing 24 connected to a fixed structure of the turbomachine such as a casing. exhaust and opening at another end to the rear of the turbomachine at the plug 14. In order to have an acceptable modal situation, that is to say push the bending modes of the operating ranges of the low floors and high engine pressures, the tube has a diameter d greater than a minimum diameter dmjn that would impose the only constraint ventilation, resulting in an undesired increase in mass as the congestion of this tube. Indeed, the eigenmode of the tube is given by the equation:

Wo = c2 / L2 * VEI / p * S with: E: Young's modulus of the material forming the tube, I: Inertia of the cross section of the tube, S: Cross section of the tube, p; Density of the material, L: length of the tube, and c constant depending on the boundary conditions.

Object and summary of the invention

The present invention therefore aims to overcome such drawbacks by providing an improved support for minimizing the size and therefore the mass of the CVT while also having an acceptable modal situation with respect to the motor frequencies. For this purpose, there is provided a central ventilation tube support (CVT) turbomachine, the central ventilation tube being adapted to be supported at one end at a bearing of said turbomachine and opening at another end to rear of the turbomachine at a plug to which a first end of this support is intended to be fixed, characterized in that it comprises pre-charge members adapted to pre-charge the central ventilation tube in tension and thus, by increasing its rigidity, push its own frequency out of the vibration ranges of said turbomachine.

By increasing the natural frequency of the tube due to the precharging thus formed, the diameter of the tube can be reduced to its minimum admissible dimension. Its mass is reduced accordingly.

According to the embodiment envisaged, said preloading members may consist of a spring adapted to be mounted between a radial portion of a second end of said support and a support element secured to said central ventilation tube or even in one or more Belleville washers adapted to be mounted between a radial portion of a second end of said support and a support element integral with said central ventilation tube.

Preferably, said central ventilation tube has a diameter dmin equal to the minimum diameter permissible to ensure the removal of oiled air from the turbomachine. The invention also relates to a turbomachine comprising such a support.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings which illustrate an embodiment having no limiting character. In the figures: - Figures IA and IB are two views in longitudinal section of a central ventilation tube held by two alternative support means according to the invention; and - Figure 2 is a longitudinal sectional view of a central ventilation tube maintained by support means according to the prior art.

Detailed description of the invention

The technical solution implemented to solve the problem mentioned above is to pre-load the central ventilation tube in tension to increase its rigidity. This makes it possible to reduce the diameter of the tube and thus to gain mass and to limit the bulk of this tube. The application of a pre-charge is carried out by adding deformable members to the support, such as a spring (embodiment of FIG. 1A) or Belleville spring washers (embodiment of FIG. Fig. 1B) or equivalent, for example.

Thus, in FIG. 1A, the cone 16 of the support 30 which is fixed by a first end 16A to the plug 14 ends at a second end by a cylindrical portion 16B surrounding the CVT 12 at a small distance (to allow differential expansion) and terminating itself with a radial portion forming a stop 16C. A spring acting in tension 32 is mounted between the stop 16C and a radial support 12A formed on the central ventilation tube 12.

Likewise in FIG. 1B, the cone 16 of the support 40 which is fixed by a first end 16A to the plug 14 ends at a second end with a cylindrical portion 16B resting on the CVT 12 and ending itself with a radial portion forming a stop 16C. Two Belleville washers 42 acting in tension 42 are mounted between the stop 16C and a radial support 12A formed on the central ventilation tube 12.

With this configuration, the natural frequency of the tube is increased due to the force exerted by these deformable members so that it is pushed out of known ranges of critical frequencies of the turbomachine essentially dependent on the rotational speeds of the low shaft pressure and high pressure rotor. Indeed, it has been shown by A.Bokaian in "Natural frequencies of beams under tensile axiai load" (Journal of Sound and Vibration) that the natural frequency of a beam increases with the pre-stressing force applied to the ends according to the following formula:

With: E: Young's modulus of the material forming the beam, I: Inertia of the cross section of the beam, S: Cross section of the beam, p: density of the material, L: length of the beam, N: effort pre-charge, and c and t constants depending on the boundary conditions. The application of this pre-loading on the central ventilation tube thus makes it possible to reduce the diameter, which depends essentially on the distances between the supports, and which can then be equal to the minimum diameter dmin necessary to ensure the evacuation of the air. oil.

Claims (5)

REVENDICATIONS 1. Support (30, 40) destiné à supporter un tube central de ventilation (CVT) de turbomachine, une première extrémité (16A) de ce support étant destinée à être fixé à l'arrière de la turbomachine au niveau d'un plug (14), caractérisé en ce qu'il comporte au niveau d'une seconde extrémité (16B) destinée à entourer ledit tube central de ventilation des organes de pré-charge (32, 42) adaptés pour pré-charger le tube central de ventilation en traction et ainsi, en augmentant sa rigidité, repousser sa fréquence propre hors de plages de vibration de ladite turbomachine.1. Support (30, 40) for supporting a central ventilation tube (CVT) turbomachine, a first end (16A) of this support being intended to be attached to the rear of the turbomachine at a plug ( 14), characterized in that it comprises at a second end (16B) intended to surround said central ventilation tube pre-charge members (32, 42) adapted to pre-load the central ventilation tube in traction and thus, by increasing its rigidity, push its own frequency out of vibration ranges of said turbomachine. 2. Support selon la revendication 1, caractérisé en ce que lesdits organes de pré-charge consistent en un ressort (32) apte à être monté entre une partie radiale (16C) de ladite seconde extrémité dudit support et un élément d'appui (12A) solidaire dudit tube central de ventilation.2. Support according to claim 1, characterized in that said pre-load members consist of a spring (32) adapted to be mounted between a radial portion (16C) of said second end of said support and a support member (12A ) integral with said central ventilation tube. 3. Support selon la revendication 1, caractérisé en ce que lesdits organes de pré-charge consistent en une ou plusieurs rondelles Bellevilie (42) aptes à être montée(s) entre une partie radiale (16C) de ladite seconde extrémité dudit support et un élément d'appui (12A) solidaire dudit tube central de ventilation.3. Support according to claim 1, characterized in that said pre-load members consist of one or more Bellevilie washers (42) adapted to be mounted (s) between a radial portion (16C) of said second end of said support and a support member (12A) integral with said central ventilation tube. 4. Support selon la revendication 2 ou la revendication 3, caractérisé en ce que ledit tube central de ventilation possède un diamètre dmin égal au diamètre minimal admissible pour assurer l'évacuation d'air huilé de la turbomachine.4. Support according to claim 2 or claim 3, characterized in that said central ventilation tube has a diameter dmin equal to the minimum diameter allowed to ensure the removal of oiled air from the turbomachine. 5. Turbomachine comportant au moins un support (30, 40) selon l’une quelconque des revendications 1 à 4.5. Turbomachine comprising at least one support (30, 40) according to any one of claims 1 to 4.
FR1560134A 2015-10-23 2015-10-23 CENTRAL TUBE OF VENTILATION PRE-CHARGE Active FR3042812B1 (en)

Priority Applications (1)

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FR1560134A FR3042812B1 (en) 2015-10-23 2015-10-23 CENTRAL TUBE OF VENTILATION PRE-CHARGE

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Application Number Priority Date Filing Date Title
FR1560134 2015-10-23
FR1560134A FR3042812B1 (en) 2015-10-23 2015-10-23 CENTRAL TUBE OF VENTILATION PRE-CHARGE

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FR3042812B1 true FR3042812B1 (en) 2019-06-14

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2997997B1 (en) * 2012-11-12 2014-12-26 Snecma AIR TUBE SUPPORT SUPPORT IN A TURBOMACHINE

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2995634B1 (en) * 2012-09-19 2018-04-20 Safran Aircraft Engines EXHAUST TUBE FOR A DEGASSING TUBE OF A TURBOMACHINE
FR2997996B1 (en) * 2012-11-12 2015-01-09 Snecma AIR TUBE SUPPORT SUPPORT IN A TURBOMACHINE

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