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Potentiels d'augmentation des performances des moteurs

Poncho (Admin)
Whisky Charlie

Potentiels d'augmentation des performances des moteurs

Message par Poncho (Admin) le Lun 2 Nov 2009 - 22:03 Powerplant Performance&channel=om

Un long article

Boosting Powerplant Performance

Nov 2, 2009

By Paul Seidenman and David J. Spanovich

As airframe manufacturers continue to develop the next generation of commercial and business jets, engine OEMs have been tasked with incorporating performance enhancements to make their products tighter on fuel burn, more environmentally sensitive, quieter and less maintenance intensive than those in service.

Improvements in engine performance are expected to be far more than incremental. For example, the "2008 Addendum To The Strategic Research Agenda, Advisory Council for Aeronautics Research In Europe" (ACARE) sets a goal for European airlines to reduce carbon dioxide emissions by 50%, nitrogen oxide by 80% and perceived external noise by 50% by 2020. At the same time, the industry must make what the council calls "substantial progress towards green manufacturing, maintenance and disposal" by 2020.

ACARE's objectives have not been lost on the engine makers. Alan Newby, Rolls-Royce chief engineer of future programs, says the OEM is trying to decrease fuel burn through two parallel research tracks--propulsive efficiency and thermal efficiency.

Pratt & Whitney's PurePower geared turbofan engine's turbine stages are made of a super nickel alloy and the compressor stages are titanium, while the gear is steel. Credit: PRATT & WHITNEY Propulsive efficiency targets increases in the engine's bypass ratio, because the higher the ratio, the greater the fuel efficiency.

"The current generation of engines normally has a bypass ratio of 10 to 11, compared to a ratio of 4 to 5" for earlier engines, Newby notes. "At Rolls-Royce, some of our research and development effort is concentrated on the open rotor design concept, which could deliver a bypass ratio of 50--or five times greater than it is today." (See sidebar p. 30 for more on open-rotor technology.)

This technology, says Newby, has the potential to improve engine fuel efficiency by as much as 30% relative to today's engines. "At the same time, we'd gain about a 30% reduction in CO2 emissions," he adds.

Thermal efficiency, Newby reports, will improve with increased engine temperatures and greater overall pressure ratios. To achieve that, Rolls-Royce is developing improved materials technology that targets the metal alloys and thermal barrier coatings to be used in turbine blade fabrication. The ceramic-based coatings would shield the turbine blades from the high operating temperatures required to increase thermal efficiency, which Newby estimates at 1,800 to 1,900 degrees Kelvin (2,780.33 to 2, 960.33 degrees F).

"The high temperature materials technologies we are developing will be applicable to all future engines," says Newby. "That includes large-engine developments, such as the Trent XWB, as well as a V2500 replacement engine for 150-seat aircraft. This technology can be applied to either improve performance by reducing cooling air requirements at a given life or to increase on-wing life and reduce maintenance costs for a given level of cooling air. Today, the airframe OEMs and their customers want to see a big reduction in operating costs," from fuel to maintenance.

Pratt & Whitney believes that technologies in its geared turbofan engine will revolutionize engine performance. It formally launched the new product family in 2008, after some 20 years of research and development. The 21,000-23,000-lb. thrust PW1500G and the 15,000-17,000-lb. thrust PW1200G geared turbofan initially will be applied to short-range narrowbody jets. Bombardier's 100-149-seat CSeries jet is the PW1500G launch customer, and Mitsubishi Aircraft's 70-100 seat MRJ is the first application for the PW1200G. Service-entry dates for the two aircraft are 2013 and 2014, respectively.

According to Alan Epstein, Pratt & Whitney's VP technology and environment, the PW1500G is projected to burn 15% less fuel than currently produced engines in its size and thrust range because of the engine's gear, which interfaces with the fan and core to allows a higher bypass ratio.

"The geared engine will have a bypass ratio of 12 compared to a ratio of 5 for the direct drive engines used on some current production 70-90 passenger aircraft," Epstein remarks. "The high bypass ratio will also make the engine 20 decibels quieter than Stage 4 noise standards."

Epstein points out that the geared turbofan represents the first fundamental shift in engine architecture since the first high bypass direct drive turbofan engines. "What's really important is that, with the incorporation of a gear, the spools spin faster without speeding up the fan," he says. "Conversely, the fan can be slowed down to speed up the rest of the engine."

Along with this, Epstein says that the gear allows for considerable engine weight savings.

"On the PW1500G, six stages of turbine machinery--three low pressure stages out of the back of the engine and three compressor stages from the front--were eliminated," he says. "Also, the gear itself weighs about as much as one low pressure turbine stage."

While the turbine stages are made of a super nickel alloy and the compressor stages are titanium, the gear is steel, a less costly material, Epstein notes. About the size of an automobile tire at 28 in. in diameter, the gear weighs under 300 lb. and can generate the equivalent of 28,000 hp. The fan case and strut will be graphite epoxy, making the PW1500G the first commercial aircraft engine with a composite fan case, according to Epstein.

"From a maintenance perspective, testing of the gear has indicated that a major inspection would not be required for about 20,000 cycles, or once every two overhaul cycles, predicated on seven to 10 years of use, on average," Epstein says. "It is very clear to us at Pratt & Whitney that a geared engine is the future. If we were in the process right now of developing a new generation of engines for widebodied aircraft, it would be a geared model."

Dr. Klaus-Peter Rued, director of advanced product design at MTU Aero Engines, reports that the company is working with Pratt & Whitney as a primary partner on the compressor and low pressure turbine for the geared turbofan engine. He explains some of the performance enhancements of the new engine.

"Compared to the IAE V2500 and the CFM56 families, the geared turbofan will deliver about a 20% reduction in fuel burn, 20% less CO2 and NOx emissions, and reduce engine maintenance costs by 30%, by using more durable metal alloys and more sophisticated design concepts for longer, on-wing life," Rued says. "The airline industry has indicated that it wants to achieve about a 40% reduction in total engine maintenance costs."

MTU, he adds, designed its share of the engine components to achieve a weight savings of 20%, also in comparison to the equivalent components on the V2500 and CFM56. That has been achieved using lighter weight metal alloys, he says.

Rued believes that the geared turbofan concept will have application to the A320 and 737 replacements, which MTU estimates will have a 2018 entry into service.

Leaping Into The Future

CFM International, the joint company of GE and Snecma, also is going after the next-generation narrowbodied transport market through the development of a 25,000-35,000 lb. thrust engine, currently referred to as LEAP-X. LEAP (Leading Edge Aviation Propulsion Program) is CFM's overall technology development program, which succeeded Project TECH56, a similar program that ended in 2005. According to LEAP Program Director Ron Klapproth, a LEAP-X engine is slated for roll-out in 2012 as a technology demonstrator.

"Our goal is to reduce fuel burn by 16% for the propulsion system, compared to the CFM56-5B and -7B models, and to reduce noise output by 15 decibels relative to today's regulations describing Stage 4," Klapproth says. "This will be the equivalent of reducing the noise level by 50% over current airplane measurements."

He points out that in addition to a 16% cut in carbon dioxide emissions, the new engine will reduce nitrogen oxide output by 50-60% relative to current certification requirements under ICAO's Committee on Aviation Environmental Protection (CAEP). "All of these improvements will use the most advanced technology under development by both Snecma and its GE partner without sacrificing the reliability record of today's products."

As Klapproth explains, LEAP-X is being designed as "a clean-sheet engine" that incorporates new materials, aerodynamic designs and cooling technology to accomplish the objectives put forward by LEAP. Among the examples of new materials he cites is the fan itself.

"In the CFM56 family, the fan blades are solid titanium, but for the LEAP-X, we will use graphite epoxy composite blades that incorporate a three-dimensional woven resin transfer molding. This will be the first time a composite has been applied to the construction of the fan blades of a small diameter (70-75 in.) fan. This is one of the key technologies in the engine," he says. "The fan case will also be composite. Together this will achieve a 1,000-lb. weight savings at the airplane level, compared to a fan of similar size made of solid metal."

State-of-the-art technology will enable CFM to realize the 50-60% NOx emissions reduction, which Klapproth calls "an unprecedented achievement," if successful. "It would be accomplished by going from a rich burn to a lean burn combustion, which uses less fuel and more air in the combustion process," he says. "To do that, the combustor will incorporate a twin annular premix swirler (TAPS), which was developed under Project TECH56."

TAP was certified by GE for its GEnx, the 70,000-75,000 lb. thrust engine selected by Boeing to power the 787 and the 747-8. "For LEAP-X, this will be the second generation of TAPS, which will deliver a lower nitrogen oxide output than the first generation TAP technology," he notes.

Other new technologies being incorporated into LEAP-X include the application to the low pressure turbine of titanium aluminide, an alloy used in the high pressure GEnx turbine. For the LEAP-X high pressure turbine, a next generation of super alloys will be employed. CFM also is evaluating a type of ceramic matrix composite for both the low and high pressure turbine airfoils and shrouds.

New powdered nickel alloy technology for the compressor and the high pressure turbine will permit the engine to run at higher heat cycles, yet deliver faster rotor speeds. "This will help us to achieve our fuel savings goal and give the engine longer life on-wing," says Klapproth.

Darin DiTommaso, manager of preliminary design and systems technology for GE Aviation, reports that the company's engine performance research and development efforts are focused on multiple platforms, from small business jets to widebodied commercial transports.

"A big area of industry focus is on the next generation of narrow-bodied airplanes, since there will be a number of those being produced," DiTommaso says. He says GE hopes to cut fuel burn by 16% over current production engines.

"To achieve that, one of the technologies we're looking at is silicon carbide-based ceramic matrix composites (CMC), which would replace super metal alloys, in such areas as the high pressure turbine. CMCs are about one-third the density of the metal alloys currently used. In addition, they are durable and more heat resistant, and therefore require less cooling air," he says.

Weight reductions and increased durability also are being achieved with the use of carbon fiber composites of bonded plies to be used in the fan blades and case. Along with lighter weight, those composites have no corrosion issues and show higher impact resistance. Carbon fiber bonded plies are used in both the fan blades and fan case on the GEnx, and for the fan blades, only, on the GE90.

"We can also get further weight reductions with the use of metal alloys such as a titanium aluminide alloy in the low pressure turbine blades," DiTommaso says. And, because the blades weigh less, the turbine disc can be made of lighter weight materials.

GE is evaluating technologies to address the issue of noise reduction, including "looking at the wake that is created by the fan blades and the interaction of that wake with the outlet guide vane," he explains.

Maintenance cost reductions also are one of GE's goals, and in that regard DiTommaso points to TAPS. "Along with reducing nitrogen oxide emissions, TAPS provides a more uniform temperature distribution which improves the lifespan of the hardware downstream of the combustor, including such high pressure turbine hardware as the nozzles, blades and shrouds. At the same time, the TAPS design eliminates the dilution holes--used to mix out the combustion gases--in the combustor liner, which should extend the liner's life. "

Honeywell Materials

Ron J. Rich, director of advanced technology for Honeywell Aerospace, says that one of the small-engine OEM's primary areas of focus is on green technology, with the objective of a 5-10% improvement in fuel burn and a 50% reduction in nitrogen oxide.

"In addition, we want to reach a noise level of Stage 4 minus 20 decibels, improved time on-wing, and more on-condition maintenance."

Among the approaches Honeywell is pursuing, says Rich, is the use of materials and technologies that will permit higher turbine temperatures and extend engine life.

"This includes the use of Alloy 10, a nickel-based, powder metal super alloy for the turbine disk, along with the next generation of ceramic thermal barrier coatings, and better effusion cooling techniques and improvements to the liner and dome of the combustor," Rich explains. Because the ceramic coatings should improve cooling of the vanes, blades and surrounding components, he says Honeywell will have more options for optimizing the combustion system. That should translate to better durability, longer time on the wing and lower emissions.

Another goal is a 40% improvement in engine power (thrust) to weight ratio. That, says Rich, means reducing the absolute weight of the engine without a power tradeoff.

Rich reports that these technological developments will be incorporated into Honeywell's new-production engines. Two near-term examples are the HTF7250G, and HTF7500E. Gulfstream has selected the HTF7250G for its G250, which is expected to enter service in 2011. The 7,400-lb. thrust engine is slated for certification by year-end 2010.

The HTF7500E, to be certified in late 2011, will be rated at 6,500 lb. thrust, and will power the Embraer 450 and 500 model business jets, projected to enter service in 2013 and 2012, respectively. Both engines are rated in the 7,000 lb. thrust range.

"The new engines will come with the ability to generate significant amounts of data for prognostics and diagnostics," says Rich, "giving the operator a better understanding of how the engines are performing and when to schedule maintenance on the various components."

Un long article donc qui fait la synthèse des nouveauté à venir

Bonne lecture

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Sam 24 Juil 2010 - 11:16

Bonjour !

Un article trés intéressant d'AIN / GE !
Concerne l'évolution à tous les niveaux des matériaux tournants dans les moteurs !
Ce qui arrive côté NG ... et pour un peu plus tard !
Je l'ouvre complet !
A lire !

-------------------------- AINonline L'article ----------------------

Engine makers engaged in quest for material grail

By: Thierry Dubois
July 20, 2010
Air Transport and Cargo Aircraft

Snecma and GE Aviation are developing new materials to make future engines lighter and improve their efficiency. In the works are alloys using exotic metals such as niobium, and composites using organic, ceramic or metal matrices. The two companies will employ these technologies for the Leap-X engine they are developing under their CFM joint venture (Hall 4 Stand B13) and possibly for other projects.

Current engines are made using titanium alloys in their cold section (that is, the fan, booster and compressor). “Titanium, which has a relatively low density, can be used up to 500 to 550 degrees Celsius,” Jean-Yves Guédou, a Snecma expert in metals, told AIN. Steel, composites and aluminum also can be found in the cold section.

For the hot section, engine makers prefer to use nickel-based and, to a lesser extent, cobalt-based materials called superalloys, he said. This means the metallurgic process has given them higher resistance to heat and mechanical stress. “Cobalt is heavier and more expensive than nickel but is slightly better at very high temperatures, around 1,100 degrees Celsius. It is also more resistant to corrosion,” Guédou said.

Next-generation Materials
In the hot section, GE has traditionally used cobalt alloys, but change is coming. About a decade ago, Japanese researchers identified cobalt-based, precipitation-strengthened superalloys as showing greater high-temperature strength. In 2006, researchers said these superalloys–made of cobalt, iridium, aluminum and tungsten–were very promising as candidates for next-generation high-temperature materials.

This is only the beginning of looming change, experts say. There are two motives driving a quest for new alloys and composites. First, as engineers try to make engines less fuel-thirsty, they tend to increase the bypass ratio. This increases the fan diameter and, in turn, makes the turbofan heavier–a condition that cries out for lighter materials.

A second way to cut fuel consumption is to improve the engine’s thermal efficiency. “If we strongly increase the compression ratio and raise combustion temperatures by around 200 degrees Celsius, we have a potential 5- to 10-percent gain in fuel efficiency,” said Vincent Garnier, Snecma’s research and technology director. This calls for higher operating temperatures for parts and therefore suitable materials, he said.

GE is already using titanium aluminide (TiAl) in its GEnx engine, which is powering both the Boeing 747-8 and 787 in test flights. A so-called intermetallic compound, TiAl features an ordered structure with strong interatomic bondings, which provide high strength at lower ductility than metal alloys. In other words, TiAl’s behavior is close to that of ceramics and, therefore, is relatively brittle. This drawback can be countered by the addition of other elements, such as niobium and chromium.

TiAl’s main feature is its ability to withstand heat up to 800 degrees Celsius, which is more than aluminum or titanium separately. Yet, its density is about half (3.9 versus Cool that of more typical nickel alloys. It also can operate in severe conditions such as high-corrosion or high- oxidation environments.

“There is a challenge in processability, which is why development has taken so long,” said Bob Schafrik, general manager for materials and process engineering department at GE Aviation. Still, the GEnx’s low-pressure turbine won’t likely be the last engine component that benefits from the use of TiAl. “We are studying other intermetallic compounds,” Guédou added.

Engineers seem to place renewed hopes in ceramics, which had been much touted in the 1980s, as they can withstand 1,300- to 1,500-degree Celsius temperatures. However, this family of materials is still in an early research stage.

Closer to production are ceramic-matrix composites, which can work at 1,100 degrees Celsius. They can used for turbine blades and nozzles, for example, Guédou said. “Ceramic-matrix composites are already tested on several of our engines,” added Schafrik, who sees applications in the next five to 10 years for powerplants such as a later version of the Leap-X.

New Metal Matrix
Another group of composites with a metal matrix also looks promising. They can be made of a titanium alloy matrix around a silicon carbide reinforcement, for example. Thanks to the strength of the silicon carbide fibers they have higher resistance, so parts can be made smaller.

“Such materials can help in designing parts submitted to high centrifugal forces and cycle fatigue,” Garnier said. This makes metal matrix composites suitable for parts in the booster and compressor, such as disks.

However, Shafrik only partly agrees with this approach. In his view, metal matrix composites are a niche material because of their high cost. “Titanium matrix composites, thanks to their strength and stiffness, are suited to certain sorts of link parts, such as long cylinders. But we usually find cheaper solutions,” he said.

Among materials used for lower temperatures, polymer resin matrix composites compete with titanium and aluminum. They can withstand temperatures of 200 degrees Celsius, or even a bit beyond, depending how long they are exposed to the temperature.

Snecma has begun full-scale endurance tests with three-dimensional-woven fan blades for the Leap-X1C–the first version of the engine, for the Chinese Comac C919 airliner. The resin transfer molding (RTM) process wraps the woven carbon fibers into a resin designed for crack resistance. The development schedule calls for the new fan blades to undergo certification tests in 2014.

The design uses the same material for the fan case. In total, Snecma expects to save 1,000 pounds in weight on the airplane, thanks to the new fan section and knock-on benefits such as the fact that a lighter pylon will be sufficient for the lighter engine. The RTM fan blade, as Snecma calls it, will be ready for the 2016 entry into service of the C919.

In the high-pressure turbine range, it is hoped that a silicon-niobium intermetallic compound will help in manufacturing more heat-resistant blades–up to 1,300 degrees Celsius. The challenge is in protecting the compound against oxidation. Tin and aluminum can be added to the mix, but while this improves the situation, it is not a complete solution so an effective coating also is needed. “We are now working on a metal-based coating,” Guédou explained. Engines equipped with silicon-niobium turbine blades will not fly until 2020, he said.

These new alloys, superalloys and compounds are less ductile–more brittle–than today’s engine materials, and engineers have to take these properties into account right from the design stage. “Manufacturing is more challenging,” Guédou said.|

Steel and Alloys
GE also wants to continue improving steel. This high-strength metal is used in bearings, shafts and gears, where strength is critical. “For a shaft, the higher the strength, the smaller the diameter, which greatly influences the configuration of the engine,” Schafrik explained.

In future engines, there is room for further improved nickel superalloys, he said. “We desire higher temperature alloys, with lower thermal expansion for some applications. Also, we have learned that protective coatings should be developed concurrently with new superalloys.”

Titanium components could be formed from “meltless” titanium powder that is derived from a vapor or liquid. “This meltless titanium technology can substantially decrease the number of major processing steps and provide large improvements in product yield, energy use and emissions,” researcher Eric Ott said in a recent paper. However, meltless titanium is still at an early stage of research and development.

Some rare materials, like rhenium, will be less commonly used mainly because there is concern about their long-term availability. “That’s a change from the past, when conventional wisdom was that such materials would always be readily available,” Schafrik said.

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Ven 30 Juil 2010 - 14:51

Bonjour !

Je ramène un poste d'un débat de !

l'intervention de M. Lightsaber ... un ingé moteurs, combustion, on ne peut plus sérieux .. me plait bien !
Au milieu d'un débat, moteurs un peu à la Cornecul, ou l'on découvre que des Check, ben ça fleurit ailleurs aussi !

L'intérêt se porte sur la comparaison entre T900 et GP7200, et Vs GE 90-115 !
Ou l'on découvre beaucoup sur les fan's aussi, dont celui du GEnX2B !

Les avis de tiers, qui sont vraiment dans le bain ... ça fait du bien de les lire de temps en temps !
Plutôt que de se laisser embobiner par des auto-proclamés experts !!!

--------------- A lire ! ------------------
rép N° 78 ! Quote Lightsaber !


I could read but not post (due to location firewall restrictions).

I'm borrowing a friend's computer to post. Baraque and Zeke have already adequately discussed the fuel burn differences.
Quoting astuteman (Reply 47):
No, they didn't.
One would expect the cruise conditions to interpolate somewhere between climb thrust and approach thrust, I guess

However, all of this data is for the estimate emissions into the 'uban air shed.' That data is made public. No airframer wishes to publish cruise emissions data. Fuel burn is published, but they usually obscure thrust by tying it to the airframe performance.

At altitude, cruise thrust is generally at 11% to 16% of maximum thrust. But the blades in the engine are much more loaded than approach thrust, but less than climb thrust.

So it isn't an apple to oranges comparison.

But, from the various data, engine performance can be estimated. The Trent 900 and GP7200 do have a lower TSFC than the GE-90-115. Technology has moved on since that engine was designed.

I've posted before that the Trent 900 promised so much (and delivered) on the A388 that GE/Pratt had to step up to the plate and add technology to the GP7200 that wasn't in the original plan. I've also posted before that Pratt *exceeded* expectations on the low spool. In particular the fan, but to a lesser degree the low turbine.

To be clear, before the GP7200, GE could not make a fan as efficient as the GP7200 fan.

The GEnX-2B has a fan that would beat the GP7200. The GEnX-1B will receive a better fan soon. Nothing like learning from the competition. (Yes, I realize this is the first time in the mid-1980's that Pratt could engineer a more efficient fan than GE. Most of my coworkers won't believe me as they're stuck believing GE is always ahead of Pratt in fan technology. Technology is never a constant.)

This isn't to say the GE-90-115 couldn't be improved. The fan and low turbine are very behind today's technology curve. Heck, GE improved the high compressor quite a bit in the GEnX.

But the technology leaps the GEnX-2B has over the GE-90-115
1. Contra-rotation (not retrofitable to the GE-90)
2. Higher Mach number high compressor (not fully retrofitable to the GE-90) Actually, not really implemented in the GP7200... but in the GEnX (but there are new tricks left to be applied).
3. "BLISK" compressors (in the past I called this 'integrated blade rotor' compressor). (Past due to put into the GE-90 for the low compressor. But to make the 777 extra competitive, this should be partially done on the high compressor. Say the first 4 or 5 stages.)
4. Newer technology fan. (Past due to put into the GE-90.) We're talking a 0.5% to 0.7% cut in fuel burn...
5. Higher aspect ration low turbine blades (tough to do on the 'hot' high turbine). This can only be partially done on the GE-90, but there is room to improve.

Quoting astuteman (Reply 49):
I noticed that also. And I am made to wonder if bypass ratio varies with thrust...

The bypass ratio does vary with thrust. It is the 'rebalancing' of the engine at high loading. In many cases, 'fluidics tricks' are applied so that the core has more airflow at higher thrust (to allow for more fuel burn).

There is a slight fuel burn penalty to design this in. Some of the extra air that goes into the GE-90-115 is by re-designing the first stage of the low compressor. (e.g., shrink the ID of the hub a little to give more area to 'capture' more air. A fan re-design must also be done to 'push' more air to the engine centerline. This isn't as efficient as designing a compressor from day #1 for 115k of thrust... but it is a heck of a lot cheaper in the engine design.)

Quoting astuteman (Reply 52):
I couldn't find a sheet for the GP7000 in the ICAO's Engine databank. I

Odd that there isn't one there...

Quoting astuteman (Reply 52):
I love RR engines, but then I love GE, P W and EA engines too.

I love engines more.

Quoting Baroque (Reply 68):
How long do we have for the chemistry lesson?

My masters degree was in combustion. How much do you want?
But seriously, everything is broken down as the non-CO/CO2 carbon atoms are counted in the chem meter. So it doesn't matter if the gas going in is CH4, C2H4, C2H6, C3H8 (combustion engineer should be shot if there is much of that coming out), etc.

Quick answer is the GE-90-115 was the 'top dog' for a while. But it is a very compromised design for the thrust due to the growth from a lower thrust engine. (e.g., as was the PW4098... sigh... it had a lower bypass ration than the PW4090, but that was done with a much larger diameter low compressor growth). The GE-90-115 had the most efficient fan at EIS and other components were excellent.

But technology has moved on. Today the most efficient fan goes to the GEnX-2B (by no means the GEnX-1B! The difference in fan technology between those two related engines is staggering). The best low compressor also goes to the GEnX-2B (duh... first BLISK compressor on a large engine. Think, BLISKS are far more effective when the Mach number of the compressor is more optimal which is never the case on a LPC on a twin spool (non-GTF)).

As to the combustor and those hydrocarbon and CO emissions. Do recall that the GE has had a ton of issues on the GE-90 combustors. Remember when they were supposed to be dual anualar lean burn? Look at a current cross section. It is a *fat* single anular design that isn't lean burn. So there is a bunch of wasted cooling air that will quench the combustion process creating those high emissions. The TAPS combustor in the GEnX is a far better concept than the dual anular.

As to the Trent-900. It is a good engine. It would be the best in the world from TSFC if GE/Pratt hadn't been 'blown off' by customers demanding a GP7200 that beat the T900 mission fuel burn. In fact, GE expected the GP7200 to tie the T900. Pratt pulled off a few surprises. There isn't any weak area I know of with the T900. So why does the GP7200 have lower fuel burn (this thread's topic):
1. The fan. Pratt kept quiet on their technology to surprise both GE and RR.
2. Higherr 'Overall Pressure Ratio' (by about 10% vs. the T900).
3. The Pratt low turbine is also more efficient than the RR low turbine. Not by much, but every bit matters. In fact, Pratt is obsessed with LPT efficiency as that is the most critical component of the engine. *
4. The "GE-90" derived components in the GP7200 have been improved to be slightly better (more efficient, in particular the high compressor) than the GE-90-115. It isn't as if GE stands still either... GE delivered a GP7200 high compressor (HPC) that was better than anything Pratt was willing to promise (and pay penalties for missing) at the time.

Now for the triple spool fans, I've gone into how the Low pressure compressor (LPC) is at a much more efficient Mach number and more importantly the mid-turbine that powers the LPC. RR is no slouch on compressors and fans either. But a summation of small advances beat them.

I'm very excited about the Trent XWB. The new 'intermediate spool' will be quite the game changer for RR.

* Final comment. Pratt internally is convinced they are far ahead of RR in turbine design. But somehow RR always beats Pratt's estimates on turbine efficiency. RR knows a trick with shrouded turbines that Pratt doesn't. For Pratt (and GE) could easily design a shrouded turbine, but their math says that the RR shrouded turbines are much more efficient than any shrouded turbine Pratt or GE could design. Hence why RR designs shrouded turbines and Pratt and GE do not bother.

Note ... si ça peut aider Sévrien à défendre un peu mieux ses RR boy's !

Poncho (Admin)
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Poncho (Admin) le Ven 30 Juil 2010 - 16:12

Punaise, il dit pas mal de bien sur le GenX2B (et même un gros paquet).
Ce qui me fait dire :
a) que le 747-8 peut être un finalement bon client non ?
b) quand est-ce qu'il passe sous l'aile de l'A330 Wink

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Jeu 2 Sep 2010 - 8:12

Bonjour !

Dans la même veine chez !
Je reproduis un post de TdsCanuck, reply 7 (Quote)

Quoting rheinwaldner (Reply 3):
Quoting tdscanuck (Reply 1):
One is going after propulsive efficiency, one after thermodynamic efficiency

How good would be a combination of both?
The benefits should be cumulative...they're basically independent technologies.

Quoting keesje (Reply 4):
it seems much of the technology used by CFM and PW , doesn't exclude each other.

Quoting aerotech777 (Reply 6):
was mentioned in the first link that the core of the Leap X will use
the concepts from lower cycle wide body engines and apply them higher
cycle narrow body environment. It will be nice if some engine gurus can
post some details about these concepts.
The major drive on Leap-X is to carry all the latest aerodynamic
improvements (most of which have come on large engines recently) back
into the smaller engines, like 3D airfoils and improved combustors, plus
a higher pressure core (greater thermodynamic efficiency).

Quoting aerotech777 (Reply 6):
the same link it was also mentioned that the Leap X will use 2 stages
high pressure turbine instead of single stage. What%u2019s the benefit
of the use 2 stages HP turbine versus single stage and is this related
to lower cycle versus higher cycle?
I don't think it's a benefit so much as a necessity. Higher
thermodynamic efficiency requires a higher pressure ratio, which
requires a more powerful compressor, which requires more turbine to
drive the more powerful compressor. If you can't get enough power
extraction from a single stage, you go to two.

I don't think these particular design features are particularly cycle related.


Ou l'on voit que 1+1 pourrait faire 2 chez P&W pour le GTF !
Mais que pour le cas du LeapX, l'efficacité du grand HBP, ne sera pas là !
D'ou mon avis positif sur le GTF, et la tendance à penser, qu'il lui reste 4-6 % de croissance quant ils décideront de pousser les T° aux mêmes limites que GE !

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 13:13

Bonjour !

Je profite de cette période creuse pour ramener un cours du maître des moteurs chez !

Bonne lecture, c'est un peu long mais ça vaut la peine !
Quote : Lighsaber, Answer 12 !

A voir si ça se lit bien !


Quoting EBGARN (Reply 5):
I believe we need to wait for Lightsaber to wake up and kill this idea,

I'm going to go into a technical discussion by component on why some of
the LEAP-X technologies would help the GTF and for some not so much.
The first thing to remember is engine blades have optimum mach numbers.
Due to NDA's, I'll talk RPM instead of Mach number, but the proper
technical operating range of a blade is Mach #, not RPM.

1. First, the fan. For this size of engine, about 3,000 to 2,500RPM is optimal.

Per this link that really doesn't understand the GTF, the low spool on the LEAP-X is about 4,200RPM!

Thus GE is doing an *incredibly* advanced fan to run it that quick (high
Mach number at the blade tips). This is a technological boost.

Pratt's fan is spining at the optimal Mach number/RPM (set the gear
ratio to ensure this), so the technological advantage of the GE fan adds
little to *nothing* for fuel burn advantage.

For GE, this fan itself adds 0.5% or so of fuel burn improvement. If the fan were put into a GTF? 0.05% (or less)

2. 2nd, the low pressure tubine (LPT). For this size of engine, the optimal RPM is 7,500 to 9,000 RPM.

GE is having to go all out with LPT advances due to the poor Mach number
through their LPT. These advances would help the Pratt, but the
diameter of the LPT is matched with the gearbox to ensure the LPT is at
the optimal Mach #. Thus (which makes me laugh at the link I found)
since Pratt's LPT is at the optimal Mach number, GE's more advanced LPT,

Now a good chunk of the LEAP-X's improvement in fuel burn is due to the
higher RPM of the LPT allowed by its adavanced fan! (They technologies
are 'synergous.')

Putting a LEAP-X LPT into the GTF would probaby cut fuel burn 2%. But
Pratt, for cost, schedule, and risk chose to *not* go with their latest
LPT in the PW1000 family of GTF's. I think Pratt could match or *beat*
GE on the LPT. So the advantage is little.

Unless GE goes with the CMC turbine...

I'll talk about CMC turbine blades later.

3. High Turbine.

Any advanced technology for the high turbine would directly apply to the Pratt GTF from the
LEAP-X. It looks like GE has figured out the direct bonding of the
termal barrier coating to the turbine blades ahead of Pratt. (Both have
worked on this since at least 1995.) This is a 2% advantage in fuel
burn adapting LEAP-X technology to a GTF.

4. Low pressure compressor (LPC).

The optimal RPM for this engine size is 7,000 to 8,500 RPM (slightly
lower than the turbine). The LEAP-X compressor benefits *more* from the
advanced technology (due to the sub-optimal Mach #) than the GTF would.

Say about 0.5% drop in fuel burn adapting it to the GTF. (Much more for
the LEAP-X, possibly as much as a 2.0% drop in fuel burn.)

5. High Pressure compressor (HPC)

GE is a bit ahead of the tech curve here vs. Pratt. Any technological
advantage would be just as usefull in either engine as both have high
spools running at their optimum Mach # compromise (turbine vs.
compressor) or optimal RPM.

GE also does more work on the pre-diffuser.

GE also does lean-burn combustors which sacrifice in flight relight but
have a lower heat load on the combustor walls. This lower heat allows
less pressure drop across the combustor liner, so that is another 0.1%
pick up in fuel burn. I personally prefer the Pratt approach (keep the
engines turning). No... the in flight shutdown rate doesn't support my
bias... I still have that bias.

6. Oil delivery to the core bearings:

GE has the tubine in the TURBINE fixed stators vs. Pratt in the
COMPRESSOR fixed stators. This cuts fuel burn about 0.3%. Pratt's have
longer oil life for a reason... This is trading fuel burn for a
trivial maintenance costs (hot oil needs more attention in the form of
additive replenishment).

Quoting tdscanuck (Reply 8):
LeapX is tackling thermodynamic efficiency, GTF is tackling propulsive efficiency. They're not mutually exclusive
In an oversimplified sense... yes. But both are improvements in
thermodynamic and propulsive efficiency. The speeding up of the low
spool on the GTF really helps the thermodynamic efficiency of the GTF.

This article has a nice optimization graph by CFM and is well worth the read to compare the two techological approaches:

If you use that graph, the 'propulsion system weight' curve drops
compared to the one drawn. The slope at larger fan diameters would be
*much* lower than a non-GTF. Why? Fewer LPC and LPT stages at
*smaller diameters* (far less weight).
The difference isn't huge, but it does shift the optimization curves
toward a larger fan for a given thrust target for a given mission.

Also the engine cruise TSFC drops more with larger fan diameter for a
GTF (asymptotes at a lower value) due to better match between fan Mach #
and LPT Mach #. Again, this drives the optimal optimization to a
larger bypass ratio than a non-GTF.

Hence the physics forces the two engines to be optimized very
differently! Both GE and Pratt went for the simplist engine (for each
vendor) that acheived a major improvement in fuel burn.

Note: The article mentions the low spool only adds 7% to the
maintenance costs... Wow... I'd swear there were a lot more labor hours
in the LPC and LPT than that. The HPT (or HPC) does drive when the
over-haul occurs, but is not 90% of the cost of the overhaul. Pratt is
also engineering for longer maintenance intervals. I like how GE tries
to claim higher gas temperatures into a turbine is low risk... Tell that
to any PW2000 customer.

In summary:
I see LEAP-X technology improving the fuel burn of the GTF only about 3%.

That is unless CFM goes forward with CMC turbine blades.
In that case I would expect the LEAP-X to *beat* the current promised
fuel burn and have a 7% benefit retrofiting the technology into a GTF.
The first engine to market with CMC turbine blades is going to be a
tough engine to compete against. I say this as a *huge* GTF enthusiast.
CMC turbine blades have been the 'technology of the future' for 30
years. If GE/SNECMA is ready...

Pratt has newer coating technologies and LPT technologies they *chose*
not to impliment for risk/cost/schedule reasons. But GE is ahead in
certain areas. But as already noted, not everything is additive when
you fix the poor Mach # of the conventional low spool. There is a
reason RR goes with Triple spools *other* than 'rebalancing.' That
reason is supperior efficiency for the booster compressor (LPC in Triple
spool talk) and 'intermediate turbine.' The issue for the triple
spool is that the Low turbine is at a very poor mach number and the
turbine at optimum mach # (you can think RPM for layman's discussion) is
more important than the compressor. But RR puts *one* (two with the
XWB) 'low' turbine stages at optimal mach #.
And yes... having *every* turbine stage at its own optimal Mach #
(RPM) would be the most aerodynamically advantagous, but that is a
maintenance and weight nightmare. Hence why turbine stages are ganged
together into 2 or 3 'spools.'

Neither GE nor Pratt wants to teach the other their tricks. Both
learned too much off of each other in the GP7200 for either to want to
repeat a joint venture. From a technical perspective, the combined
engine would be a little more efficient. But...

Quoting PPVRA (Reply 3):
from the "it's wrong to put a gun to someone's head and tell them what
to do" argument, you are combining not just technology potentials, but

Pratt didn't do their most advanced fan nor their most advanced LPT due
to the risks. Heck, the HPC is also not 100% 'leading edge' due to
maintenance and surge risks. The LEAP-X doesn't have everything GE
could do either (my contacts consider it quite the 'rushed engine' for
the level of technology in it). Risk management is always part of
engine design.

Quoting SEPilot (Reply 7):
There is nothing that spurs innovation more than competition

Some joint ventures work well. But that is usually because there is
some competition. (e.g., EA GP7200 vs. T900). Both Pratt and GE are
looking over their shoulders at some future Chinese engine. The V2500
produced a better engine than RR or Pratt could have done solo back
then. Today the cost of a joint venture to either Pratt or GE is more
than the value in further reduced fuel burn.

Quoting keesje (Reply 10):
Airbus tried to pull RR into the GTF via IAE. It didn't work.
Pratt's only hope to return into the civil engine market strong is the
GTF. Neither GE nor RR is ready to deliver an engine (heck, not even
launch one) soon. In about 5 years, RR will be ready (they've been
working on GTF's quietly per my rumor mill). GE would be a few years
behind if they chose to start investing the billions required to catch

So unless Pratt was *guaranteed* a partnership on every engine for the
next 20 years, they will not give up their intellectual nor patent
rights. Please ask further questions.



Merci pour le cours Lightsaber

Dernière édition par Beochien le Mar 7 Sep 2010 - 13:17, édité 1 fois
Poncho (Admin)
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Poncho (Admin) le Mar 7 Sep 2010 - 13:15

C'est petit !
Je vais triturer un peu ça

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 13:19

Merci ! Poncho !
Je viens d'en mettre une couche !
A toi maintenant, je n'y touche plus !

Poncho (Admin)
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Poncho (Admin) le Mar 7 Sep 2010 - 13:33

Le coup de l'optimisation différente entre entre un GTF et un non GTF était bien visible dans le pavé de la NASA qui tu avais donné en lien...
Deux moteurs assez différents

Cela dit 3% de mieux en injectant les techno du LeapX en pouvant se permettre d'attendre qu'elles soient mature c'est déjà pas mal.

Lu au passage un truc du style RR + GTF ? J'ai révé ou bien ? Wink

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 13:40

Non, Poncho ! Il y en a qui rêvent !
Mais d'ici 2020, le GTF posséde 4-6 % d'évolution possible, en partant dans les technos "Chaudes" présentes ou à venir type CMC, en avance chez GE !
Je poursuis l'édition de Lightsaber ça vaut la peine !
J'espère qu'il nous le pardonnera !
C'est un Ingé "Combustion" de haut niveau ayant travaillé sur xx projets, et qui peut être a changé aussi de cies US, de ce que j'ai compris !
Je publie la suite !

Poncho (Admin)
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Poncho (Admin) le Mar 7 Sep 2010 - 13:44

Enfin pour moi un réducteur n'a rien de honteux
Mais je dois être un peux trop intoxiqué par les belles machines de la SNCF à rapport de réduction modifiable à l'arrêt ou en marche, au besoin avec une grosse clé... pour faire du marchandise lourd et lent puis du voyageur moins lourd et rapide avec la même machine
et là je parle d'environ 3000 ch à réducter (sans trop de contrainte de poids).... et ça a tjs été un cauchemar opérationnel...

CC6500 notamment

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 13:59

Ben, chez moi ça a commencé avec le variateur de ma 1ere Mobylette !
Pas facile de la (Le) faire monter à 85 km/h!
Mais en Aero tous les luxes sont permis ! Matéraux, taillages hyper rectifiés etc ! Et un tx de réduction fixe, ce qui arrange bien !
Et les épicycloîdes, à engrenages multiples ça arrange bien aussi, l'effort est largement réparti, et sur toute la périphérie du carter (Hou Hou le TP 400) !
Le couple assez constant aussi, pour trouver l'équilibre !
J'ai plus confiance dans la méthode P&W, que dans les engrenages du TP 400, avis perso !
Mon ADN familial m'a dit, il y à bien longtemps (Viscount-Vanguard) que ces foutus réducteurs posaient plus de PB que les propres moteurs !
Mais le temps à passé, merci aux nouvelles technos !

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 14:06

Bonjour !

Lightsaber réponse 14 (Quote)
Merci au professeur !
La suite ce soir ! Mais pas interdit de la lire sur !

Typo above:
The fan should have an optimal RPM of 3,000 to 3,500 RPM.

Quoting faro (Reply 13):
for the detailed reply Lightsaber. IIRC however, doesn't the EJ200
already have CMC turbine blades? In that case, what is the impediment to
having them on civil engines? Not reliable enough maybe?
There have been several engines with CMC blades adapted to them... PR
releases touting the technology and then a quiet replacement of the
blades (and rotors) with conventional materials.

Also recall the cycle life difference between a military engine and a civilian engine.

Wide body civilian engines go for 2,500 to 4,000 cycles between overhauls.
Narrowbody civilian engines go for 6,000 to 10,000 cycles between overhauls.

The US military does the most training, so they demand a cycle life near a widebody engine.

Most other Air Forces demand a far shorter life. The shortest I'm aware
of was a cycle life of 200 for many of the cold war Russian designs.
(The war was won or lost by the 20th cycle per their theory.)

I do not know the Eurofighter engine cycle life, but I know it at most
1/3rd of what Pratt is promising with the GTF. The high turbine is the
most expensive part to service... its cycle life sets the overhaul
interval. Hence why CMC's will have to be mature for the LEAP-X. I
missed they were in the Eurofighter. If SNECMA was the vendor... then
they can help do the LEAP-X turbines...

The issue with CMC's is fatigue life. In particular thermal stress
crack propagation. This is a NASA paper for a different application,
but it does a good job of explaining the fatigue and stress on vanes.
Civil aviation turbine blades would be designed with less stress (far
longer cycle lives), but the design methodology is the same:

High cycle fatigue, low cycle fatigue, and creep as still and issue with
CMC vanes. Thermal stress is far more of an issue with CMC vanes than
nickel vanes (where it is still a major issue!). Hence, why it has been
the technology of the future for a long time...

Quoting faro (Reply 13):
Wouldn't the GTF derive some % fuel burn benefit from these too, if only in reducing overall engine weight?
Yes, but due to the lower fan RPM (in this case RPM is the appropriate
engineering term), the reduced centrifugal force on each fan blade makes
the weight penalty *far* less in a GTF than in the high RPM LEAP-X.


Merci Lightsaber !
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 19:59

Bien, comme promis !

Professeur Lightsaber Part 3 nous parle des re-motorisations des MC !
Quote Lightsaber , réponse 17 !


Quoting aerotech777 (Reply 16):
I am not mistaken CFM-5C and CFM-565B are fitted with the same core
engine. How each engine is optimized to each use: one for short/medium
range aircraft and the other for long range aircraft.

I apologize if this post is out of the subject

Its on subject enough to talk how optimizing the same components ends up with different results.

First, let's understand the background of the core of the CFM-56. The
F101 engine for the F-15. It is a core designed to take rapid
transients and a decent number of cycles (IIRC, contract target for the
F100/F101 was 3,000 cycles). By pushing the cores a little less, one
gets excellent narrow body cycle life.

But this is a high cycle core. In other words, it is lacking a 2nd
stage HPT and associated compressor stages. So it is a core that is
'sub-optimal' for long stage lengths. Why? Overall pressure in the
engine is lower as a twin stage high turbine (HPT) is the most efficient
way in a twin spool to achieve thermodynamic efficiency.

So how does one get more thrust and better long haul TSFC? It is
possible to put on additional low pressure turbine stages. Thus
powering a larger fan.

By taking a cycle durability hit, the core is being 'pushed harder'
(higher temperatures rotate the core faster producing a higher pressure
ratio). The combination of enlarging the fan and pushing the core
harder (dumping in more fuel into otherwise the same engine) produces
the added thrust required on the A343 at a lower TSFC. (Running a core
harder always produces better efficiency.)

Due to the extra low turbine stage, the exhaust pressures of the fan and
turbine are compatible to be 'mixed.' This improves propulsion
efficiency (the core air is still exiting faster than the fan air, so
'mixing' creates a more homogeneous exit velocity profile which is
always more efficient).

The cost? Weight. Thus not an optimal engine for short hops. Also, by
pushing the core so hard, the ratio of climb thrust to max takeoff
thrust is less. (The harshest wear and tear on the turbine is at the
end of climb and so a core that has more fuel dumped into it will wear
far more than the -5B variation of the engine with its smaller fan.) So
a -5C on the A320 wouldn't be economical just do to the low cycle life.
But on the A343, which was intended to do far longer missions than the
A333 (its stable mate for a long time), is unlikely to see 'high cycle

The cost benefit is one reason widebody engines almost always have half
the cycle life of narrow body engines. For long missions, the cost
savings are greater cutting fuel burn versus how many takeoffs to the
next shop visit. (More hours of fuel burn per takeoff is another way of
looking at it.)

Quoting Starlionblue (Reply 15):
Indeed. For a good aviation example, just look at WWII. 20-30 years of technological progress packed into 5-6.[/size]

While true, the cost was high in 'upheaval.' Just talking about the aerospace industry, let's talk winners and losers.

Curtis: Went from being a *major* global aerospace provider to a component vendor.
Boeing: Blew Consolidated out of the water, which gave them a profitable franchise (707 tanker was helped)
Douglas: The C-47 (military DC-3) made them the defunct global propeller transport supplier.
Pratt: Became the dominant transport engine vendor.

Now, I only mentioned US companies as WWII made aerospace a 'mass
produced' industry instead of a 'craft industry.' For example, Merlin
engines made by RR had higher horsepower and reliability than Packard
produced engines (team built versus assembly line engines). But the
assembly line allowed Pratt to out-produce everyone.


Merci Lightsaber !

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 20:08

Et un petit couplet pour remonter le morale de Jeddih !

Du professeur Lightsaber !
Qui verrait bien un petit trois arbres pour les MC NEO !

Quote Lightsaber Rép: 20 !

-----------------------Toujours De ------------

Quoting thegeek (Reply 18):
From reading Lightsaber and Tdscanuck's posts, I'm starting to wonder why not a triple spool narrow body engine?
I wonder too. All indications were that RR was ready for a competitive
triple spool down to 25k of thrust. Airbus rejecting their proposals on
fuel burn implies that the weight penalty for the bearings and such is
too much for this low thrust level.

I need to be clear. A triple spool, due to the inherently more
efficient RPM of the intermediate turbine (and booster compressor) is
lighter than a double spool at high thrust (> 90k lbf). Why?
Component efficiency (more optimum Mach number on the turbrine and
compressor blades) allows for fewer parts (fewer rows of compressor or
turbine blades). But for a small engine, the added weight of the
shafts, bearings, and rotors (having two rotors is much heavier than one
for the 'low spool' of a double spool becomes the 'low spool' and
'intermediate spool' on a triple spool).

I expected RR to counter with an effective triple spool on the A320
re-engine. I'm enthusiastic as to the theoretically excellent costs of a
narrow-body triple spool. I would have to have someone from RR break
their non-disclosure for me to understand why their projected fuel burn
wasn't good enough.

Note: I expect cruise fuel burn to be less than the GTF or LEAP-X. But
climb fuel burn and maintenance would be so much better that most
narrow body missions would benefit. I really thought the greatest
threat to the GTF would be a small triple-spool and not the LEAP-X. So
if anyone has any good links, I'd like to learn more as to why Airbus
rejected the triple spool (Yea, I read cruise fuel burn, but there is
more to it than that...The climb fuel burn should have offset that


Merci Lightsaber !

Whisky Quebec

Re: Potentiels d'augmentation des performances des moteurs

Message par Vector le Mar 7 Sep 2010 - 20:21

Lightsaber vs. Darth Vador,
Jeddih vs. Daddy
On est en plein délire freudien !
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 20:29

Mouais Vector !

Suis bien content d'avoir repéré un vrai Ingé qui bosse sur les sujets, et est à jour, lui !
Ca vaut mille on dits, des soi disant porteurs de la vérité universelle !
Lightsaber est ouvert pas manichéen pour 2 ronds, et ses avis sont à noter !
Il connaît mieux d'ailleurs GE et P&W, que le Phœnix inter-galactique , spécialiste actuel de la mise sur orbite, des disques de MPT : RR, à Derby, doit encore compter les étoiles filantes dans leur firmament ! !
Ne le répêtez pas, un des disque du TRENT1000 serait sur le point de quitter notre système solaire, direction Alpha du Centaure, pour témoigner de la puissance universelle de RR !
Lobbying unlimited, maintenant les équipes sont presque en route pour les appuis locaux peut être nécessaires !

Whisky Quebec

Re: Potentiels d'augmentation des performances des moteurs

Message par Vector le Mar 7 Sep 2010 - 21:13

Oui, tout à fait d'accord, cela fait pas mal de temps que je suis ses posts. Seul réserve, c'est un spécialiste de la combustion, il n'a qu'une vue superficielle des aspects thermodynamiques du cycle compression étagée-détente. C'est une constatation habituelle avec les Américains, ils sont spécialisés dans une niche étroite. J'aimais mieux discuter avec les ingénieurs de SNECMA qui avaient une vue plus vaste, bien que la technologie ne soit pas exactement la leur, avec un fort accent germanique (pour les ATARs).
Personnellement, j'aurais une préférence pour P&W. Ce sont de vrais inventeurs de technologies, alors que GE a toujours plus ou moins copié et amélioré des modèles étrangers. Quant à RR, ils ont le mérite d'avoir sorti l'Olympus 593 du Concorde dont l'économie n'était pas la principale qualité (je voulais mettre une photo, mais ça marche pas). SNECMA a conçu les TRA-28, double reverse à paupières.,r:3,s:0
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 7 Sep 2010 - 21:19

Ca marche trés bien ! superbe !
Whisky Quebec

Re: Potentiels d'augmentation des performances des moteurs

Message par Vector le Mar 7 Sep 2010 - 21:23

Oui, mais je voulais le mettre en URL et ça ne marche pas. Le lien est OK. Je ne suis pas doué avec les manips de graphiques !
Ceci dit, le décollage du Concorde de SIA/BA de Heathrow est une des choses les plus impressionnantes que j'aie vues. Les 2/3 de la piste en roulant et une rotation qui porte bien son nom, puis une fusée. Remarque j'ai vu la même chose avec le B-1B au Bourget depuis le chalet de Boeing, mais il devait être à vide car il n'a même pas fait la moité de la piste. Une station de coco devait l'attendre pas loin !
Le plus drôle, c'était la ruée des Russes et satellites avec des téléobjectifs comme je n'en avais jamais vu. C'est sûr qu'ils étaient intéressés... pour le Blackjack.
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Jeu 10 Fév 2011 - 9:25

Bonjour !

Un très long et intéressant article de Geoffrey Thomas sur ATWonline !
Concerne la fiabilité, en immense progrès, et les ETOPS !
Une longue historique de ces progrès réalisés depuis 30 ans!
Du 1° Février, pas encore vu, je crois !
De vieilles et moins vieilles histoires apparaissent de temps en temps ... Wink

A lire, bon courage !

When Failure Is Not An Option !

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Mar 4 Déc 2012 - 21:07

Un article bien intéressant de Flight Global !

Les possibles retombées de programmes de recherche du côté de l'"Air Cooling "
C'est dans le camp de la très haute vitesse today, mais ça pourrait redescendre !
On l'espère bien, mais pas pour demain !
Peu d'explications sur la techno !

----------- A lire ! de FG, Dan Thisdell, un extrait et le lien -------------

Reaction Engine's SABRE rocket engine relies on an exotic heat exchanger capable of cooling intake air - from as much as 1,000˚C (1,832˚F) at Mach 5.5 to an almost-cryogenic -150˚C - to provide the near-liquid oxygen required to provide rocket thrust when mixed with tanked liquid hydrogen.

The technology, formally "signed off" by the European Space Agency in November as viable, will now be the subject of a £250 million ($400 million) investment drive, which Reaction Engines hopes will raise funds to develop a demonstrator.

However, while the company's focus will be on its SABRE concept, Reaction Engines believes its cooling technology, which transfers heat from the air to tanked liquid hydrogen fuel by running it over a huge network of 1mm tubing, could augment a "standard" aero gas turbine in two ways.

Reaction Engines technical director Richard Varvill says a SABRE-style heat exchanger could feed cool air to compressor blades. In current gas turbines, the hot-section blades are running at temperatures above the melting point of the metals they are made from, and have to be cooled by pumping less-hot air through internal holes, the formation of which greatly complicates blade manufacture. Better cooling with colder air may permit even hotter combustion.

Another technique would be to use a heat exchanger to take heat from the exhaust and feed it back into the combustion chamber, thereby getting work from energy that would otherwise be wasted.

Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Jeu 14 Juil 2016 - 1:47

Tiens, marrant, un peu de recherche nocturne sur le pitch de fan variable ....

Trouvé qq chose qui a été breveté en 1999, preuve qu'on s'y intéresse depuis longtemps, l'ennui étant le poids et les énormes forces centrifuges sur les aubes encore nombreuses, et les solutions sont rares !

Au centre des brevets et autres expérimentations, nombreuses, et une cie, Rotating Composite Technologies Ct, issue de AC I (Aerocomposites) et grands amis de UTC, Hamilton Sustrand !
Plus qq contacts avec GE, des brevets qui ont circulé vers Textron aussi pour l'exploitation du moins !
Harry Griswold, (PH) dans tous ces coups , un ancien de chez UTC -  Hamilton S.
Whisky Charlie

Re: Potentiels d'augmentation des performances des moteurs

Message par Beochien le Jeu 14 Juil 2016 - 2:08

Et marrant, au passage le brevet qui couvre le Fan Alu de UTC/ P&W !
La protection Titane collée à l'époxy ...

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Re: Potentiels d'augmentation des performances des moteurs

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