RR dévoile son plan pour le marché des avions d'affaires. Je copie puisque c'est derrière le paywall:
Ne reste qu'à trouver une plateforme à motoriser.
Rolls Unveils Business Jet Engine Game Plan.
Apr 11, 2017 Guy Norris | Aviation Week & Space Technology
Rolls-Royce is taking greater advantage of its larger civil engine advanced technology initiatives to boost development of a new generation of business aviation powerplants. The first full-up fan demonstrator is expected to run later this year.
The ramp-up of work on the technology demonstrator, dubbed Advance2, signals a new phase for the manufacturer, which has revealed few details of its future business aviation family initiative until now. Covering the 10,000-20,000-lb.-thrust range, the plan is to develop three Advance2 demonstrators with two different core sizes and three different low-pressure systems.
These will p
rovide a springboard into a new family series for entry into service in the early 2020s, with market demand driving the thrust level of the launch variant. The initial demonstrator is targeted to provide similar thrust levels to the BR725, the most powerful engine in Rolls’s business aviation portfolio.
The Advance2 initiative closely parallels the company’s next-generation commercial turbofan development plan, which is centered on a new-technology core dubbed Advance3. The new commercial core is scheduled to run at the heart of a full demonstrator engine in Derby, England, around midyear, and is intended to form a steppingstone toward development of the Advance and UltraFan engine families next decade.
Future Two-shaft Family Tests
Advance2 targets 10,000-20,000-lb.-thrust range
Tests will focus on two cores and three low-pressure spools
Entry into service from 2020
Program closely aligned with Advance3 commercial demonstrator
“The key point from business aviation is that we have refocused our technology programs over the past year to get much more synergy between the commercial large engines and the business aviation products,” says Joe Hoelzl, chief project engineer for future programs at Rolls-Royce Deutschland, the company’s center of excellence for two-shaft engine development.
Although Rolls continues to dominate the high-thrust engine market for large-cabin, long-range business jets with more than 3,000 powerplants in service and continuing sales of the BR700 and AE3007, the company’s position is under attack. Rolls is therefore stepping up its next-generation plan after acknowledging its grip on the sector has slipped following aggressive competition from General Electric and Pratt & Whitney Canada.
Both GE and P&WC have made significant incursions into Rolls territory during the past seven years. GE’s Passport engine, originally the TechX, was launched in 2010 for Bombardier’s Global 7000/8000, while P&WC’s 16,000-lb.-thrust-class PW800 was announced in 2014 as the powerplant for the Gulfstream G500/600 family. Despite these losses, Rolls believes everything is in play in a market that it forecasts will need up to 9,000 new aircraft over the next 10 years.
Architecturally similar to today’s BR700 family, the core of the Advance2 will be smaller but more powerful, and efficient. Credit: Rolls-Royce
“We have nowhere to go but down,” says Scott Shannon, senior vice president for customers at Rolls-Royce Business Aviation. “GE has made no secret of getting into business aviation in a big way and wanting to break up the Rolls monopoly, in part because it is an attractive market. But make no bones about it, we will defend our position very vigorously. We are investing in the technology but it is going to be tough competition, no doubt about it,” he adds.
“We can’t stand still,” says Rolls’s business aviation product strategy executive, Frank Moesta. “We have lost a little bit, but we are fairly sure we can keep our market position and extend it again. So what’s the next step? We call it Advance2.”
Building on the baseline core architecture of the 10-stage high-pressure compressor and two-stage high-pressure turbine used in the BR700 series, the Advance2 introduces a suite of new technologies that will provide the foundation for a new family.
The Advance2 plan aims to achieve a technology readiness level ready for full-scale development by the 2020s with a specific fuel burn 10% lower than for the BR710. In terms of emissions, the new family will have a 50% margin to the latest International Civil Aviation Organization Committee on Aviation Environmental Protection regulations while dispatch reliability is targeted at 99.99%. Thrust-to-weight ratio relative to the BR700 is expected to grow by 20% and the bypass ratio to about 6.5:1.
The initial Advance2 demonstrator is targeted at a thrust level similar to the current BR725, one of which is shown under assembly in Dahlewitz, Germany. Credit: Rolls-Royce
Because absolute size of fan diameters is necessarily limited by the conventional fuselage-mounted engine configurations and higher Mach cruise speeds of current and projected long-range subsonic designs, the fan is not expected to see the sort of dramatic growth of larger commercial engines. The relative increase in bypass ratio therefore derives from the introduction of the smaller core of the more advanced gas generator.
“We have a 48-in. fan on the BR710 and a 50-in. fan on the BR725, but the biggest Advance2 will feature only a 52-in. fan. So we are packing a much more efficient product into the same nacelle envelope and that’s one of the key factors to making high-speed aircraft work,” says Hoelzl.
With Advance3 running slightly ahead of schedule of its smaller sibling project, Hoelzl adds that “the larger engine technology will be mature, and we will have to do some miniaturization of that to get it ready for the business aviation programs.” Like the Passport and PW800, the new Rolls engine will have a one-piece blisked fan rotor. It also is expected to include a lightweight fan case to keep overall weight down, an important driver for access of large business jets to smaller, restricted airports.
“We have already done multiple rig demos, and in the aerodynamic rigs the Advance2 fan shows stability and good performance. We have done bird-strike rig tests, as well as fan blade-off rig tests. The next step is to run this in a full engine, which we will run maybe later this year. Watch this space,” Hoelzl explains.
The new high-pressure compressor “is the heart of the engine,” he notes. Comprising titanium blisks in the front stages, the design increases the pressure ratio to 24:1 from the 16:1 of today’s BR700. “This is the key enabler in terms of making the core physically smaller, lighter and higher-performing. It also results in higher temperatures that have improved the thermodynamic performance, and contribute toward a 40% higher overall pressure ratio,” Hoelzl says.
The 3D aerodynamics of the compressor have been tested extensively in a full-scale aeromechanical rig. “We have over 115 hr. of tests covering the full operational range under our belt,” Hoelzl continues. “We have fully demonstrated the pressure ratio and stability targets, and we have learned quite a lot in terms of speed, altitude and bleed settings. We have optimized the stage loading as we enter the second phase of engine testing.”
At the rear of the core is a two-stage, high-pressure shroudless turbine. “The differentiator is that today the turbine is fully shrouded,” he says. The turbine change, which leverages designs developed for military engines such as the EJ200, is possible because of the advent of improved high-temperature materials and advanced cooling technology.
“We found shrouds were limiting in terms of speed. The smaller the core goes, the faster it runs, and the speed is limited by the tip speed which is going supersonic. So shroudless is a step change and breaks a barrier in terms of turbine capability,” Hoelzl explains. Rig testing has been underway with—and without—a combustor and an all-turbine rig test is underway in cooperation with DLR, the German aerospace research agency.
Composites form a key element of the design. The Advance2 will incorporate lightweight outlet guide vanes made from composites that combine structural and aerodynamic functions, while the exhaust system will make extensive use of an oxide-oxide ceramic matrix composite material set.
The low-pressure (LP) turbine will be the most efficient and lowest noise unit ever developed by Rolls for a business jet engine. “This is where we have synergy with the large commercial engines,” says Hoelzl, who adds that the smallest Advance2 will have two LP turbine stages like the BR710, the midsize variant will have three like the BR725, and “here, for our biggest member of the Advance2, we are going for four stages.”
In conjunction with DLR in Cologne, Germany, as well as other facilities, Rolls is also conducting an extensive series of rig tests of advanced low-emissions combustor technology. The company is using additive layer manufacturing to advance both the designs themselves, as well as the time taken to test them. “It has allowed a step change in our combustor technology,” says Hoelzl. “We basically are printing the combustor cans in sectors and welding them together, which allows us to do more experiments in terms of cooling hole locations.” Time between rounds of experiments has dropped from around a year to just four months, he adds.