RR Trent XWB

Rolls-Royce has drawn up a technology-insertion roadmap aimed at enabling its Trent XWB turbofan to deliver the nominal 92,000lb (409kN) of take-off thrust required by the stretched A350-1000 when it enters service in 2015.

sevrien a écrit: (i) J'avas dit que des BCL parlaient dans le vide sur les "airframe" A350-XWB et moteurs Trent XWB,.. & leur ai répété ad nauseam que les "thrust settings" des RR Trent XWB-800 / -900 / - 1000 n'avaient pas été approchés, sans parler d'être définis ! J'avais dit qu'il incombait à Airbus de préciser suffisamment la définition générale de l'avion, pour permettre à RR de travailler concrètement avec Airbus sur cet aspect !

(ii) Nous venons d'apprendre officiellement que les réglages de poussées maximales des moteurs RR Trent XWB vont pouvoir être réduiits :
-- de 3,000lbs pour le Trent-XWB-1000 (depuis la poussée de 95,000lbs, initialement indiquée, au niveau de 92,000lbs);
-- de 4,000lbs pour le Trent-XWB-900 (depuis la poussée de 87,000lbs, initialement indiquée, au niveau de 83,000lbs);
-- de 1,000lbs pour le Trent-XWB-800 (depuis la poussée de 75,000lbs, initialement indiquée, au niveau de 74,000lbs).

(iii) du coup, le "core" va pouvoir être réduit en taille et en poids, tandis que le diamètre de la soufflante ("fan diameter") va pouvoir être maintenu à 118 pouces (il avait été déjà réduit d'un pouce depuis 119 pouces), la consommation en sera réduite, et il y aura des améliorations aérodynamiques dans le moteur, et sur le "airframe", et les pylônes, nacelles & ailes, .... ensemble "mieux optimisé" encore, pour le fuselage et le moteur !

Rolls-Royce has drawn up a technology-insertion roadmap aimed at enabling its Trent XWB turbofan to deliver the nominal 92,000lb (409kN) of take-off thrust required by the stretched A350-1000 when it enters service in 2015.

The UK manufacturer plans to introduce a strengthened fan system, and materials and aerodynamic modifications in the core of the -1000's Trent XWB, to ensure that the top-end member of the engine family offers comparable time-on-wing to the variants that will power the baseline A350-900 and -800 "shrink".

The -900 is due to enter service in 2013 equipped with an 83,000lb-thrust engine, followed by the -800 a year later, which will use an identical powerplant de-rated to 74,000lb.
Airbus and Rolls-Royce are expected to tell airline customers at an A350 programme review meeting in Hamburg in early April that these thrust ratings are being revised slightly upwards, following the airframer's recent decision to raise maximum take-off weights.

"Our basic strategy on this engine is we have a single engine type," says Trent XWB chief engineer Chris Young. "We design it originally for the -900, nominally an 83,000lb-rated engine at the moment, and that engine we absolutely optimise for a 2013 entry-into-service level of technology."

However Rolls-Royce confirms that the 350-seat A350-1000, which will have a maximum take-off weight of 298t, will require a modified engine.

"What we have said is that rather than build a slightly bigger core or slightly bigger fan [to cater for the -1000], we'll optimise it as well as we can for [the -900 in] 2013, then we'll insert new technology for 2015 that will allow us to build the thrust rating up," says Young.

The basic 118in (3m) titanium fan will be retained for the -1000, but the blades and casing will be strengthened to allow for the higher flow rate.

There will also be an increase in the operating temperature capability of the core, taking advantage of new turbine technologies developed through the European Environmentally Friendly Engine (EFE) research programme.

"The technology insertion is really more around recovering your time-on-wing back to the same sort of levels as the 83k engine, by giving you a greater turbine gas temperature margin," says Young.

Core changes will mainly concern turbine blade design, materials, coatings and cooling technology.

The stakes could not be higher as Rolls-Royce begins transitioning its newest large turbofan into production. The Trent XWB is the sole offerable powerplant to equip the European airframer's flagship 250- to 350-seat A350 XWB long-range twinjet family, designed to single-handedly see off the formidable two-pronged competitive threat posed by Boeing's General Electric GE90-powered 777-200LR/300ER models and the long-delayed mid-market 787.

Airbus can perhaps sleep a little easier in the knowledge that the Trent XWB is the latest evolution in a long line of three-shaft large turbofans that began with the introduction of the Trent 700 on the A330 in the 1990s. The family subsequently grew to include the Trent 800 for early 777 models, followed by the Trent 500 for the A340-500/600, Trent 900 for the ultra-large A380 and, most recently, the 787's bleedless Trent 1000.

Despite the Trent XWB's heritage, R-R has not missed the opportunity to incorporate cutting-edge technology into the new powerplant and has made some significant advances even compared with the Trent 1000, which is yet to fly on the 787.

An unprecedented challenge for the engine maker has been the requirement to design from the outset a common engine for all three major A350 variants: the baseline -900, -800 shrink and -1000 stretch, due to enter service in 2013, 2014 and 2015 respectively.

"There is a clear mix of heritage: a great platform to build on, but great technologies being built into the engine," says Trent XWB chief engineer Chris Young.
Airbus's decision to abandon its initial plans for the A350 (which would have essentially involved bolting 787-technology engines on to a revamped A330 airframe) and switch to the all-new XWB concept, left R-R with the task of addressing the 74-92,000lb-thrust (329-409kN) band with one engine family.

Young describes this as "a reasonably large thrust range, but nothing outside the capability of what we've done in the past. It's pretty much the same as the Trent 800". He adds, however, that a key difference is that a "very planned approach right up front" is being taken to that thrust range.

Historically, engines at the higher end of such a family have tended to be "throttle-pushed" ('thrust-bumped") and run at hotter temperatures, while those at the lower end have been oversized for the airframe and therefore too heavy.
"The challenge is catering for a very large thrust range while making sure that you don't kill the maintenance costs for the engine at the top of the thrust class, and you don't kill the fuel burn of the one at the bottom of the thrust class," says Young.

THRUST RATINGS
Following recent airframe weight increases announced by Airbus, the final thrust ratings for the three A350 variants are due to be revealed to airline customers at a programme progress review in Hamburg on 2 April.

The current ratings, nominally 74,000lb (for the -800), 83,000lb (-900) and 92,000lb (-1000), are expected to be revised slightly upwards to cater for the new airframe operating weights.

"Our basic strategy on this engine is we have a single engine type," says Young. "We design it originally for the -900, nominally an 83,000lb-rated engine at the moment, and that engine we absolutely optimise for a 2013 entry-into-service level of technology.
"The -800 engine is identical, we just derate down to that [74,000lb] level, but that allows us to deliver outstanding hot-and-high performance," he adds.

However, the 350-seat A350-1000, which will have a maximum take-off weight of 298t, will require a modified engine.

"What we have said is that rather than build a slightly bigger core or slightly bigger fan [to cater for the -1000], we'll optimise it as well as we can for [the -900 in] 2013, then we'll insert new technology for 2015 that will allow us to build the thrust rating up," says Young. The message from existing and prospective A350 customers was "make sure that you don't compromise the smaller aircraft through total commonality", he adds.

The engine that will power the A350-1000 will therefore incorporate two significant modifications. The first of these is a new fan system, although the basic 3m (118in) fan diameter and blade aerodynamics will be retained. "If you looked at it from 10 paces you wouldn't notice the difference," says Young.
For the -1000, the fan will be run at a higher speed to achieve the required flow rates, and will therefore be equipped with thicker titanium fan blades and a stronger fan casing.

...... C'est une question de "hot & high", dont Airbus n'a pas dû avoir la même appréciation fine que le motoriste (normal ; ce n'est pas son job).

Aujourd'hui, le motoriste n'a envie de changer ni la configuration du moteur ni ses dimensions, car toute modification dans ces domaines entraînerait des complications indues, créerait des risques de déséquilibre jouant sur l'aérodynamique de l'ensemble de l'appareil, et, ensuite, pouvant empêcher la réalisation / l'obtention des efficacités visées, surtout celle de la consommation !

Young points out that using the strengthened fan system across the whole engine family would have added excessive weight to the variant for the A350-800, while the fan "doesn't need much maintenance and can stay with aircraft", therefore mitigating the impact of the loss of commonality.

The second change to the A350-1000's Trent XWB will be an increase in the operating temperature capability of the core, taking advantage of new turbine technologies developed through the European Environmentally Friendly Engine (EFE) research programme.
"We've a number of options as to what we need to do [for the A350-1000], but we don't need to finalise our decision until around about the middle of next year," says Young.

The changes will mainly concern turbine blade design, materials, coatings and cooling technology, and capitalise on concepts due to be tested on the EFE demonstrator.
"That suite of technologies, if they all come good, is more than we need [to achieve 92,000lb for the -1000]," says Young. "We can have a drop-out rate of them not quite being ready on time, and we'll still be perfectly capable of achieving the required thrust rating."

Lire notre post ci-dessus, du Mer 4 Mar - 0:25 !
Due to the common fan size, which enables the use of an identical titanium forging for the casing, "the level of commonality actually ends up being huge", says Young.

Although the baseline Trent XWB - optimised for 83,000lb of take-off thrust for the A350-900 - would be able to run at up to 92,000lb for the -1000, the fan and core changes are being introduced to maintain durability..

"The technology insertion is really more around recovering your time-on-wing back to the same sort of levels as the 84,000lb engine, by giving you a greater turbine gas temperature margin," says Young. "It's a maintenance cost resetting via use of technology.".

The engine core improvements developed for the 2015 entry-into-service of the A350-1000 could eventually be incorporated into earlier versions of the Trent XWB that will by then be in service on the -800/900 models..

"The intent is that the new core [for the -1000] would have the capability of being read across to all of the previous [-800/900] engines" says Young, who adds that decisions to upgrade engines already in service will be looked at on a case-by-case basis..

Ultimately, the cruise thrust required across the three A350 derivatives is broadly similar, because they share a highly common wing..

"When people ask how can you effectively and efficiently do one [engine] that covers the whole [A350] family - well, it's not the headline take-off thrust number that you're really trying to optimise around," says Young..

The basic architecture of the Trent XWB was finalised in mid-2007, including fan diameter, the number of compressor and turbine stages and core size. Subsystem configuration was frozen in September 2008. Towards the end of last year contracts were agreed with the 12 risk- and revenue-sharing industrial partners.
"We're on the point of freezing the design, launching all of the parts into manufacture and some of the long lead time parts are there already," says Young. Bench testing of the first engine is to begin in the second quarter of 2010, with certification targeted for the end of 2011.
The flight-test programme for the A350 itself is scheduled to get under way in early 2012, but the Trent XWB is due to get airborne aboard A380 MSN001 during the first half of 2011..

COMPUTER MODELLING
Young says that to make maximum use of the latest computer modelling techniques and rig-testing to reduce the risk of development problems arising downstream, "far more resource" has been put into this programme in the early stages than before, "when it can have the biggest effect and we have time to react"..

On previous programmes maturity testing began after certification, but these two "streams" of work are being done in parallel for the Trent XWB. "It's a restructuring of the way we run these programmes," says Young. .

The Trent XWB's 3m, 22-blade titanium fan is 51mm (2in) wider than the Trent 900's and therefore the biggest yet produced by R-R..

"We've ended up with a core a bit smaller than the Trent 900, even though the thrust is a bit higher," says Young. The 9.3:1 bypass ratio XWB is also the first Trent to feature a two-stage intermediate-pressure turbine, which Young says "puts growth capability into the engine", ...........

........and is the first to incorporate blisks, which have seen several years of successful service in the Boeing 717's BR715 turbofan..

Another milestone for the Trent XWB is the ability to modulate the amount of air bled to cool the turbine blades, further optimising cruise efficiency.
Relative to the engines powering first-generation widebodies such as the 747, R-R predicts the Trent XWB will deliver 28% better fuel burn, and expects a 15% improvement relative to the first iteration of the Trent 700.

Having worked so closely with Airbus to tailor the three-shaft Trent XWB to meet the requirements of the A350, R-R sees challenges for rival engine manufacturers GE or Pratt & Whitney, should they choose to offer an alternative powerplant.
"We've had the benefit of being able to set the [A350's] engine cycle around the three-shaft engine," says Richard Keen, R-R head of marketing for Airbus programmes........

...... "There'd be compromises for a two-shaft engine that tried to adapt to the same cycle and fan size that we've set," he adds.

The 12 partners on the Trent XWB are responsible for just over 40% of the workshare (see graphic), of which three are described by R-R director of risk and revenue sharing partners Bill Boyd as "cornerstone". ITP, in which R-R owns a large minority stake, is responsible for the design and manufacture of the low-pressure turbine (LPT) module, while Kawasaki Heavy Industries has the intermediate-pressure (IP) compressor module, and Mitsubishi the LPT blades, IP turbine discs and parts of the combustor.

TRIM2 a écrit:Bonjour,
Oui, sevrien.

RR a beaucoup d'atouts en main sur ce TRENTXWB.

Dommage que le site de RR soit devenu moins explicite..

A+

Beochien a écrit:Ben, s'ils l'essaient sur l'A380 ! le Trent XWB !
Ils feraient aussi bien d'en mettre 4 d'un coup un jour !
Et 2 sur le A330 (s'il est encore au catalogue dans 3-4 ans)!
Comme celà, 3 avions pour le même moteur !
La commonalité pour la flotte LC ... le pied !
Sévrien, pense que ce sera le T900 qui évoluera pour le A380 !
Moi ... je n'en suis pas convaincu ...
Surtout si le corps du T-XWB est plus petit que celui du T900!

sevrien a écrit:

Beochien a écrit:
Je me demandes d'ailleurs ou va aller le GP7200, si les incidents se multiplient ! Ils vont rester sur une petite centaine d' A380, et aprés ...
Et, avec des upgrades à prévoir vers 2013 .... en plus, et le 380/900 !

Le problème est que les Associés de l'EA, GE & P&W, ont de mauvaises relations entre eux, et n'ont aucune volonté stratégique, industrielle, commerciale ou financière dans la poursuite de ce projet, en termes d'évolution technologique.

Ils savent que le moment viendra, où il serait impératif de faire, comme avec n'importe quelle projet de motorisation, un genre de "mid-life upgrade" / 'amélioration de mi-vie' (ou équivalent), pour 'rafraîchir' les moteurs en opération, de manière à aider les clients à "rajeunir" leur flotte respective , en lui donnant un coup de fouet, comme :
-- RR est en train de faire / de préparer avec les RR Trent 700EP (pour les A330 en opération ; ou "new build") ;
-- IAE a commencé à faire avec les IAE V2500 selon la formule "SelectOne".

En fonction :
-- du 'diagnostic' / de l'évaluation des flottes et de la base-moteurs installée,
-- des desiderata des clients, et des possibilités envisageables & / ou disponibles et réalisables,
-- dans des conditions mutuellement acceptables sur les plans économique / financier & du "timing",......

une panoplie de solutions peut être proposée, selon un planning adapté aux clients sur mesure : (i) 'kits' d'améliorations ciblées pour rétro-insertion, (ii) rétro-fit majeur de modules substantiels, (iii) remplacement des moteurs existants avec "standard en new-build", correspondant à une remotorisation, avec amélioration ambitieuse, mais réaliste et sans constituer un "step-change" technologique, ni entraîner d'autres grandes modifications à "l'airframe" par exemple.

RR sera bien positionné pour ce qui précède, et pourrait même prévoir une nouvelle génération de moteur pour les futurs A380-800 & -900 (distincte même des RR Trent XWB), qui s'insérerait dans la lignée des Trent, comme évolution avantageuse à risque faible, et pour un prix bien contenu.

Airbus en serait ravi, parce que cela prolongerait l'habitude qu'il apprécie d'avoir un moteur spécifique, sur mesure, pour chaque famille d'avions Airbus, comme une mini-famille de moteurs (à deux poussées bien adaptées, dans le cas des A380, pour deux variantes, par exemple, à partir d'un "same bill of material").
....

Beochien a écrit:
Commentant les comparaisons de "Gains" annoncées ...

Relative to the engines powering first-generation widebodies such as the 747, R-R predicts the Trent XWB will deliver 28% better fuel burn, and expects a 15% improvement relative to the first iteration of the Trent 700

Beochien a écrit: .... et en extrapolant, (Si c'est en sfc on peut essayer ? )... on peut penser que le T XWB va faire 10% de mieux que le dernier T700 et peut être dans les (+/- 8%) versus les T900 ??.... et devrait atteindre 5-6 % de mieux que la génération du T1000 / GEnx (Modèle de vol)!

Beochien a écrit: Et on attends de voire ce que donne le GEnx2 sur le 748 pour avoir une idée aussi vis à vis du 747 !

Quel est le meilleur moteur sur le B787 ?
GEnx ou trent 1000?

A ce stade, je n'ai aucun avis. Trop tôt pour le dire ! Personne ne peut le dire.
......
Les deux produits seront excellents. Ce sont des "game-changing engines" pour un "game-changing aircraft". Les deux auront des avantages et désavantages mineurs l'un par rapport à l'autre. En vrac, sans chercher à faire un bilan plus favorable, ni hiérarchiser les avantages ou désavantages, voici quelques remarques.
--
(i) Il ne serait pas étonnant que, lors des premières mesures, le GEnx ait un minuscule avantage sur le plan de la consommation. RR arrivera, sous peu, à combler le léger désavantage. Les consommations seront à peu près identiques. Mais, voir "Efficiency Retention"/ 'Retention d'efficacité'.

(ii) Retention d'efficacité : RR Trent 1000 aura l'avantage à ce titre. Il y aura des répercussions, à l'avantage de RR, sur les plans :
-- de l'entretien,
-- et de la consommation, après 3 ou 4 mille heures d'opérations du moteur, dans chaque 'cycle entre entretiens', quand l'efficacité du moteur commencera à baisser plus vite côté GE que côté RR (avantage à l'architecture à 3 Arbres de RR par rapport a celle à 2 arbres du GEnx),
-- "time on wing" / temps sur l'aile sans dépose,... qui fait partie de l'ensemble du 'paysage'.

RR a dépensé des fortunes (Recherche, R& T, Application) sur les aspects qui permettent de prolonger le "time on wing", dans toutes ses catégories de moteurs, y compris ses moteurs à 2 Arbres (AE 3007, Tay, BR-710 / 715, et l'IAE V2550 de cette "joint-venture", notamment sous les programmes Vision et Select).

Traditionnellement RR a toujours devancé GE dans ce domaine. Le record mondial de tous les temps de "time-on wing" appartient à un RR RB211-535-E4 d'Icelandair (B757-200, avant même l'époque des Winglets, qui auraient tendance à prolonger ... ),.... qui a battu celui d'un CFM-56 (GE/SNECMA). CFM-56, à part la variante avec 'combusteur annulaire double', inaugurée par la défunte Cie. Swissair (variante qui fut un véritable désastre ; ça arrive) & vite abandonnée, est plutôt bon en "time-on wing", mais dépassé maintenant, depuis quelques années, par le rival IAE V2500, plus moderne, et construit de façon modulaire, permettant, chaque fois où cela est nécessaire & / ou opportun,...
-- de faire l'entretien sur l'aile, par le remplacement du module concerné.

Bien entendu, le but est de pouvoir déposer rapidement et remplacer, lors des cycles pre-programmés par IAE (où les principaux acteurs sont RR & P&W, à parts egales, épaulés par les FRSP MTU & le Japonais JAEC).

Cet aspect "Time on Wing" est très important dans la facilitation de la gestion des flottes, et de la compression des coûts d'entretien.

(iii) Risque "statistique" ; vu la maturité accumulée de la famille Trent, par rapport à celle -- moindre, inévitablement -- de la famille GEnx, précédée par la famille GE90, l'avantage est simplement ce qu'on appellerait le "lowest-risk option", ou, si l'on préfère, le meilleur équilibre entre 'technologie & risque'.

Mais cela n'est que le risque 'statistique'. En matière de technologie, il y a un avantage pour le RR Trent 1000, dans sa configuration "more electric", tout comme le GEnx dans cette configuration ou environnement "more electric", .. qui est le "piquage d'énergie électrique " / electric power off-take du "spool à Pression intermédiaire ", ce qui aide à réduire bruit, vibrations & consommation.

Evidemment, cet aspect important n'est tout simplement pas disponible sur un moteur à architecture à 2 arbres !

(iv) Le RR Trent 1000 sera plus court & léger que le GEnx correspondant, soit 750 kg à 800 kg. "par ship-set" (d'où moins de traînée induite, plus de compacité & de rigidité interne, là ou il faut), et plus facile à transporter, notamment dans son berceau.

(v) Chaque moteur, Trent & GEnx, sera conçu pour être "environmentally friendly", et réalisera de belles performances, voire des prouesses à ce titre.

(vi) Les côuts "of operations & ownership" pourraient être légèrement mieux cernés côté RR Trent, grâce à toute l'expérience accumulée dans la gestion de la famille Trent (avantage / retombée de la maturité précitée).
--------------

(vii) Un point spécifique : dans l'état de l'art actuel ("in current state of the art") l'architecture à 3 arbres permet une meilleure gestion "at idle" des moteurs, et, par là, une économie au niveau de l'usure des freins. Pendant le roulage, moteurs à "idle", dans le 'taxi-ing avant décollage', les avancées par petites distances, lorsqu'on est dans la queue, en attente de décollage, et en train de progresser par a-coups vers le décollage, les moteurs à 3 arbres sont plus faciles à gérer / contrôler. Les petits bonds en avant, par a-coup, sont bien moins saccadés que dans le cas de moteurs à 2 arbres. De ce fait, les multiples petits freinages usent moins les disques sous motorisation Trent (3 arbres ) que sous P&W ou GE (2 arbres). Mesures faites sur des dizaines d'années, déjà ! Economies annuelles considérables, au niveau de la flotte, surtout si la flotte est grande(environ GB£ 1 million par an, par avion) !

Ceci explique, pour partie, pourquoi on continue les recherches sur des moteurs électriques, fonctionnant sur l'atterrisseur du nez, pour aider à conduire l'avion jusqu'à son lieu de décollage, sans faire marcher les réacteurs. On fait des économies de carburant & sur entretien des freins !
---
Malgré ces commentaires, il est impossible, à ce stade, de dire quel moteur, RR Trent 1000, ou GEnx, est 'le meilleur'.

The Engine
As a member of the Trent family, the Trent 800 is built on sound fundamentals:
Three-shaft architecture
Commonality is provided across all its members through use of the successful three-shaft architecture. Derived from the reliable RB211 family, this architecture permits low-risk scaling from existing designs providing lower development costs, proven technology and in-service reliability leading to optimised engines for specific aircraft applications.

Wide-chord fan
The hollow, titanium wide-chord fan blade, pioneered by Rolls-Royce and introduced into airline service in the 1980s, set new standards in aerodynamic efficiency and resistance to foreign object damage. Designed specifically for high-bypass turbofans, the breadth of these blades sets them apart from the narrow and less efficient equivalents of earlier times.

Lightweight structure
The three-shaft engine design makes the Trent engine shorter and simpler. The simplicity and inherent efficiency of its design also means that modern three-shaft engines produce significant weight benefits. A Trent 800-powered Boeing 777 is around 7,500lb (3,402 kg) lighter than the same aircraft powered by the heavier of the competing engines. Low weight and high thrust equates to optimum revenue earning capability.

Best performance retention
Its three-shaft configuration provides good performance retention resulting in more time on wing and fewer shop visits throughout its life. Deterioration characteristics have been minimised through: preliminary design (e.g. single case combustor for reduced leakage, advanced clearance control in the turbines, and optimised clearances in the compressor); and operation (advanced engine health monitoring, and engine core washing).

Best environmental credentials
The Trent 800 produces the lowest NOx and the lowest total legislated gaseous emissions during landing & take-off with significant margins to both current and future regulations whilst using a simple, cost effective single-annular combustor. The Trent 800 also has significant margin to both Stage 3 and Stage 4 community noise legislation levels.

Superior economics
Due to its low weight, three-shaft architecture and proven reliability record; coupled with low idle thrust reducing brake wear, and low oil consumption the Trent 800 continues to demonstrate superior operating life-cycle economics.

Intelligent Engine Health Monitoring will facilitate pro-active maintenance in order to eliminate operational disruption and maximise part usage through cycle counting. The Trent XWB will incorporate the latest noise and emissions reduction technology. The combustion system will be further developed from the Trent 900, which has the lowest emissions of any in-service engine, and from the Trent 1000. This will ensure the Trent XWB will beat all current and proposed environmental legislation.

art_way a écrit:Bonsoir à tous,

une question bête :

Est-ce que les moteurs RR sont plus chers ou moins chers que les GE ou PW ?