World's Most Powerful Turbofan Engine
THE INTRODUCTION
The engineering is so difficult that to this day, GE is the only company with composite fan blades in service. They work inside the GE90 and the GEnx engines that power many Dreamliners. The material allowed GE engineers to design blades that result in lighter and more efficient engines, allowing airlines to save fuel by shedding precious pounds. Now the engineers are busy building the future. They are working on a fourth generation of the blade for the GE9X, GE’s largest engine yet, designed exclusively for Boeing’s next-generation wide-body jet, the 777X. GE has already received orders and commitments for 700 GE9x engines valued at $29 billion (list price) from several growing Middle Eastern airlines like Emirates, Qatar and Etihad, as well as Lufthansa, Cathay Pacific and All Nippon Airways. Last November at the Dubai Air Show, Emirates also signed a $16 billion deal with GE Aviation to service its GE9X engines for a dozen years after they enter service.
The GE90 Engine
Built by General Electric in conjunction with SNECMA of France, IHI of Japan and FiatAvio of Italy, and first commissioned by the British Airways for its new fleet of Boeing 777s recently (September 1995), it is the most powerful commercial aircraft engine today. Certified at a Take-Off Thrust of 380 kN (85,000 lb.), only two engines suffice for a huge aircraft like the 777 with a seating capacity of 375 (weight approx. 230 tonnes). A derivative of the GE/NASA Energy Efficient Engine (E 3) program, it is also the most fuel efficient, silent and environment friendly engine of today. In addition to the highest thrust to be offered, the GE90 is expected to provide airlines with a 5-6% improvement in fuel burn, lower noise pollution, and NOX emissions 33% lower than today’s high bypass ratio engines.
Higher Thrust Variant
For Boeing's next-generation 777 long-range versions (later named 777-200LR and 777-300ER), greater thrust was needed to meet the specifications. General Electric and Pratt & Whitney insisted on a winner-take-all contract due to the $500 million investment in engine modifications needed to meet the requirements. GE received sole engine supplier status for the higher-thrust engine variants for the 777-200LR, -300ER, and 777F/.
These higher-thrust variants, GE90-110B1 and -115B, have a different architecture from the earlier GE90 versions, with one stage removed from the HP compressor and an extra stage added to the LP compressor. A net increase in core flow was achieved. General Electric performed a similar re-staging exercise when they upgraded the CF6 from the -6 to the higher thrust -50. However, this thrust growth route is expensive, since all the downstream components (e.g. turbines) must be larger for flow capacity. The fan is an advanced, larger diameter unit made from composite materials and is the first production engine to feature swept rotor blades.
The higher-thrust GE90-115B mounted on GE's Boeing 747 test aircraft.
The GE90-115B is powerful enough to fully operate GE's Boeing 747 testbed on its own power, an attribute demonstrated during a flight test.
GE90 Ground and Flight Testing
With FAA certification of the GE90, GE Aircraft Engines brought to close one of the most extensive ground and flight test programs ever undertaken by an engine manufacturer.
GE announced the development of the GE90 in January 1990. In November 1992, the first full-scale engine core went to test; the first full engine followed in March of 1993. Since that time, GE and its revenue sharing participants have run a total of 13 development engines which have verified the engine’s inherent design benefits. Overall, the engines have logged more than 5,000 hours, including 228 flight hours on GE’s modified Boeing 747 flying test bed.
GE90 endurance engines completed more than 14,000 cycles and demonstrated excellent section durability. Seven engines have operated at more than 100,000 lb. (444.5 kN) of thrust, with one achieving a recordbreaking 110,000 lb. (489 kN) of thrust. In fact, GE90 development engines have sustained thrust levels in excess of 100,000 lb. (444.5 kN) for more than 65 hours.
As part of the required certification testing, the GE90 successfully completed both the 2.5 and 8 lb. (1.13 and 3.63 kg) bird ingestion tests on the engine’s composite blades.
In October 94, four 2.5 lb. birds were ingested with the engine running at speeds required to produce 85,000 lb. (377.8 kN) of thrust at takeoff on a hot day. There was no thrust loss and the engine responded to all throttle commands during the required 20 minutes of operation following the ingestion. All fan blades were in excellent condition and have continued to run in other engine tests.
In mid-November 94, GE conducted the fan bladeout test with the FAA present. The release blade was detonated at a fan speed of 2,485 rpm, 10 rpm over the target, with the engine generating more than 105,000 lb. (466.8 kN) of sea level static (SLS) corrected thrust. The engine mount system performed as designed and the test demonstrated fan blade containment.
The ruggedness of the composite fan blade was successfully demonstrated, 8 and the observed trailing blade damage matched pre-test analysis, verifying the inherent benefits of the composite blade design.
The GE90 flew for the first time in late 1993 installed on the 747 flying testbed. Throughout the first phase of testing, the engine accumulated nearly 228 hours in 45 flights. The engine performed exceptionally well, demonstrating performance levels that were better than specification and provided pilots unrestricted throttle movement throughout the flight envelope.
GE90 design
The GE90 is designed for :
• Thrust Growth.
• Engine commonality for the 777 Airplane Family.
• Fuel Efficiency.
• 180-Minute ETOPS (Extended Twin OPerationS).
• Low Emissions.
• Low Noise.
• Reduced Operating Cost.
Cycle Selected for significant fuel savings.
• Bypass ratio optimized.
• Overall pressure ratio optimized.
• Designed for lowest SFC and fuel burn.
Designs selected for maximum airline benefit.
• Designed and demonstrated technologies for high reliability.
• Builds on CF6 and CFM56 reliability.
• ETOPS approval.
• Operator developed maintenance procedures.
• Designed for low noise and low emissions.
• Designed for Lowest Operating Cost.
Engine Sized For Future Aircraft Requirements.
• Initial certification at 84,700 lb. (376.5 kN) thrust - February 1995
• First growth certification at 92,000 lb. (408.9 kN) thrust - May 1996.
• Potential to grow to 120,000 lb. (533.4 kN).
GE-90 Turbofan Cycle Analysis
Following are the results of a simple high bypass ratio turbofan engine cycle analysis carried with the help of a computer program. The theory of the analysis can be found in. A more extensive and accurate analysis can be obtained from. The available data on the GE90 engine was merely limited to its take-off thrust, bypass ratio (BPR) and overall pressure ratio (OPR). The rest of the data is tentative and is assumed on the basis of other similar GE engines (like CF6-80C2 and CFM56) with the appropriate improvements considered.
Engine Data
Intake efficiency = 0.980
Fan polytropic efficiency = 0.930
Compressor polytropic efficiency = 0.910
Turbine polytropic efficiency = 0.930
Isentropic nozzle efficiency = 0.950
Mechanical efficiency = 0.990
Combustion pressure loss (ratio) = 0.050
Fuel combustion efficiency = 0.990
Area of hot nozzle = 1.0111 m2
GE90-94B
General characteristics
Type : axial flow, twin-shaft, bypass turbofan engine
Length : 287 in (7,290 mm)
Diameter : overall: 134 in (3,404 mm); fan: 123 in (3,124 mm)
Dry weight : 16,644 lb (7,550 kg)
Components
Compressor : axial: 1 wide chord fan, 3 low pressure stages, 10 high pressure stages
Turbine: axial : 6 low pressure stages, 2 high pressure stages
Performance
Maximum thrust : max at sea level: 93,700 lbf (416.8 kN)
Overall pressure ratio : 42:1
Thrust-to-weight ratio : approx. 5.6:1
GE90-115B
General characteristics
Type : axial flow, twin-shaft, bypass turbofan engine
Length : 287 in (7,290 mm)
Diameter : overall: 135 in (3.429 m); fan: 128 in (3.251 m)
Dry weight : 18,260 lb (8,283 kg)
Components
Compressor : axial: 1 wide chord swept fan, 4 low pressure stages, 9 high pressure stages
Turbine: axial : 6 low pressure stages, 2 high pressure stages
Performance
Maximum thrust : max at sea level: 115,300 lbf (514 kN) ; world record set at 127,900 lbf (568.9 kN) in testing 827 feet above sea level
Overall pressure ratio : 42:1
Thrust-to-weight ratio : approx. 6.3:1
GE-90 And The Environment
Reduced Emissions and Smoke
• Dual Dome Combustor.
• Reduced Noise.
• Low Fan Pressure Ratio and large aspect ratio low pressure turbine.
• Overall lower mission total fuel burn = Lower total mission pollutants.
• Higher thrust to core flow ratio.
GE90 Combustor Provides Improved Operability with Reduced Emission Levels
• Double Annular Combustor.
• Pilot dome optimized for operability - main dome optimized for high power.
• Emissions reduction Based on 15 years of NASA and Advanced Military Engine Development.
• Full-scale GE90 Testing.
• Exit temperature profiles meet design intent.
• Emission levels verified.
Transportability
• Designed for Standard Engine Transport Methods.
GE-90 Propulsor
• Smaller than the high bypass turbofans of today
• Allows replacement of propulsor only
• Separate Propulsor/Nozzle from Fan Stator Module
• Fan stator module remains at main base or with aircraft
• Removal and Replacement Time Estimated at Less than 6 Hours
FUTURE OF GE90
Thrust Growth
GE90 components are sized for growth. If the market requires it, 110,000 lb.
(511 kN) of thrust could be produced by a GE90 with further investment. The
following are the ways General Electric intends to achieve the thrust
increment -
• 376.5 kN Fan
Certification Engine.
B777 “B” Market.
• 409 kN Fan
Improved LPT Materials.
Increased HPT Cooling and 1st Stage Blade TBC.
B777 “B” Market.
B777 Stretch.
• 422.3 - 435.6 kN Fan
Improved Turbomachinery.
• 466.8 kN Fan
Higher P/P Fan with Destaged Core.
• 511.2 + kN TF
Higher Speed and P/P Fan with Destaged Core.
Komentar
Posting Komentar