Corso di Motori Aeronautici

Mauro Valorani

Laurea Magistrale in Ingegneria Aeronautica (MAER)Sapienza, Universita di Roma

Anno Accademico 2011-12

FP7 Aero Engine Scenario

Sett. 13: Conclusioni

1 FP7 Aero Engine ScenarioERS StrategyTargets CO2 & NOX ReductionVITAL Concepts

COUNTER-ROTATING FAN

DIRECT DRIVE TURBOFAN

GEARED TURBOFANNEWAC Core Concepts

SP 1: Whole Engine Integration

SP 2: Intecooled Recuperative Core Concept

SP 3: Intecooled Core Concept

SP 4: Active Core Concept

SP 5: Flow Controlled Core Concept

SP 6: Innovative Combustor

FP7 Aero Engine Scenario

Lez. 26: Conclusioni

FP7 Aero Engine Scenario

FP7 Aero Engine Scenario

FP7 Aero Engine Scenario

ERS Strategy

ERS Strategy

FP-5: EEFAE (Efficient and Environmentally Friendly Aero Engine) andSILENCER (Significantly Lower Community Exposure to Aircraft Noise) were inpreparation towards the ACARE targets on engine level. The CLEAN(Component Validator for Environmentally-friendly Aero-Engine) demonstratoraimed at the validation of components for the future concepts.

FP-6: two integrated projects have been set-up:

VITAL focused on technologies for low pressure system improvements toreduce CO2 and noise.New combustor technologies and new engine core configurations will bedeveloped to find a significant and durable reduction of pollution within theNEWAC (NEW Aero engine Core concepts) programme

FP7 Aero Engine Scenario

Targets CO2 & NOX Reduction

Targets CO2 & NOX Reduction

FP7 Aero Engine Scenario

VITAL Concepts

VITAL Concepts

Technologies developed in VITAL will be incorporated in three basic configurationsinvolving the low-pressure section including the fan. The improvements expected fromeach of these layouts will be evaluated against the requirements of the type of flight(short or long-haul). Three basic architectures are investigated:

Direct Drive Turbofan (DDTF), a re-optimized tradeoff between fan and turbinerequirements considering the low weight technologies introduced in VITAL.

Geared Turbofan (GTF), combining a fan with a reduction gear train, to allowdifferent rotating speeds for the fan, and the booster and turbine.

Contra Rotating Turbofan (CRTF), with two fans turning in opposite directions,allowing even lower rotation speeds, since the two fans split the loads involved.

FP7 Aero Engine Scenario

VITAL Concepts

COUNTER-ROTATING FAN

The counter-rotating turbofan (CRTF) concept developed by Snecma isparticularly innovative. This layout simply means that there are two independentshafts, rotating in opposite directions. At the other end of the low-pressuresection, they are joined to a low-pressure turbine with several stages ofcounter-rotating blades. For a given aerodynamic load, this configuration willreduce the fan rotating speed by 30 percent or more. This fan concept is a greatleap by offering the same performance as a conventional fan it manages the sameairflow -, but with slower tip speeds, reducing fan noise. Therefore, enginesdevelopment would be able to follow a new trend enabling a higher bypass ratiowith lower fuel burn. Acoustic tests will be carried out at different speeds, withdifferent blade configurations. Each rotor will have significantly fewer blades thana conventional fan. Tests will be performed on a 1/4-scale model at the Russianresearch center CIAM (Central Institute of Aviation Motors), already a partner toSnecma on several initiatives.

FP7 Aero Engine Scenario

VITAL Concepts

DIRECT DRIVE TURBOFAN

The Direct Drive Turbofan (DDTF), concept developed by Rolls-Royce, remainson a similar configuration as engines of today, but would contain the increase ofweight of the engine through novel lightweight materials and structures. Thetargeted high bypass ratio is 10 to 12. As a result of the higher bypass ratio thefan speed and pressure ratio will be reduced. Acoustic and aerodynamic tests of afan rig will be performed at Anecom in Germany. Designs for low weight and noiseLP turbines will be aerodynamically and acoustically tested in Germany, Italy andSpain. Mechanical tests of the novel fan blade, casings and structures will also becarried out.

FP7 Aero Engine Scenario

VITAL Concepts

GEARED TURBOFAN

The Geared Turbofan (GTF), concept developed by MTU, is also based on astandard technology but targeting higher bypass ratios (12-15). The GTF whichrevivals through the use of a gear placed on the engine axe, needs that VITALteams to develop new technologies for compressors and the low-pressure turbine.The GTF evaluations will use the same fan technology as the DDTF, bothaerodynamic and mechanical.

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC Core Concepts

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC SP 1: Whole Engine Integration

For all core concepts the requirements and objectives are defined, starting with whole

engine performance cycle data. The programme compares, assess and ranks the benefits

of the advanced concepts, ensuring consistency of the results and monitoring progress

towards the ACARE technical and economic objectives. The new engine designs will be

assessed in typical aircraft applications as indicated in figure 1.

Environmental Risk Analysis), previously created in the VITAL programme, in order to

compare the environmental and economic impacts of the new designs. Issues to be

addressed include performance, weight, engine installation, NOX and CO2 emissions,

noise, fuel costs, maintenance cost and aircraft flight path and altitude. The

socio-economic model will identify engines with minimum global warming potential and

lowest cost of ownership as shown in figure 2.

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC SP 2: Intecooled Recuperative Core Concept

This concept exploits the heat of the engines exhaust gas and maximises the heat pickup capacity of the combustor inlet air by intercooling in front of the HP compressor.EEFAE-CLEAN results showed potential in the optimisation of the recuperatorarrangement (innovative duct design, radial compressor in a new design area).

Centrifugal HP Compressor

Centrifugal compressor efficiency improvement and high hub-tip-ratioOptimisation of radial compressor/ducting interfaceRadial/axial compressor comparison

Recuperator

Improved heat exchanger and nozzle arrangementLow loss heat exchanger integrationStructural and overall IRA integration aspects

Future innovative core configuration

Variable core cycleInnovative combustionContra-rotating coreUnconventional heat management

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC SP 3: Intecooled Core Concept

To utilise the CO2 benefits of a high overall pressure ratio cycle for a given NOX leveland material technology, an intercooler is included in front of the HP compressor. Twokey technologies of the intercooled core concept will be investigated in detail. One keytechnology is the intercooler and the related ducting, which has to handle the full coremass flow and will be validated by rig tests.Then, specific HPC technologies are needed to react on the increased operability needsdue to the added volumes in the compression system (intercooler, ducting) and the highOPR. These HPC technologies will be validated with rig tests.

Intercooler an related ducting

Design and test advanced cross-corrugated plate heat exchangerDesign and validation of low pressure loss ductsAdvanced OGV/diffuser

Improved HPC (higher overall pressure ratio)

Stability enhancement for intercooled core operability needsImproved blading and secondary flow pathImproved tip clearance design

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC SP 4: Active Core Concept

Active systems offer the possibility to adapt the core engine to each operating conditionof the mission and, therefore, the potential to optimise component and cycle behaviour.The active cooling air cooling system will be investigated for reduced cooling airconsumption. To increase the effiency and the operability, the HP compressor will beequipped with a active clearance control system for the rear stages and a active surgecontrol system for the front stages.

Active clearance control system (rear stages)

Improved tip clearance with active clearance control system (thermal ormechanical)Comparison with alternative technologies for tip clearance improvement

Active surge control (front stages)

Development of an active surge control with air injectionComparison to the passive alternative multi stage casing treatment

Active air cooling

Gerneral conceptAir cooler and control systemCombustor case cooling air flow pathHPC rear cone cooling

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC SP 5: Flow Controlled Core Concept

High BPR direct driven turbofan engines require a compact HP compressor with veryhigh PR, which has to compensate for the low booster PR. Flow control technologiesare investigated in NEWAC, which help in the specific field of very high aerodynamicloaded HPC to strongly increase efficiency and stall margin.

Tip flow control and advanced aero

Advanced casing concepts (Casing treatment, casing aspiration, tip injection)3D optimised aerodynamicStall active control integration

Aspiration concept on blade profiles

Aspiration concept on blade profilesEvaluation and optimisation of aspiration technology on stator vane/hubs orbladeIdentification of potential benefits

Rub management

FP7 Aero Engine Scenario

NEWAC Core Concepts

NEWAC SP 6: Innovative Combustor

All promising approaches for significant NOX emission reduction are on the basis of

lean premixing combustion technology. Lean combustion technology operates with an

excess of air to significantly lower flame temperatures and consequently significantly

reduce NOX formation. The optimisation of homogeneous fuel-air mixtures is the key

to achieve lower flame temperatures and hence lower thermal NOX formation.

However, this homogenisation has a strongly adverse effect on combustion lean

stability, drastically narrowing the operating and stability range. Low NOX technology

is difficult to scale to various engine sizes. As a consequence, depending on the overall

pressure ratio of the particular engine application, different injector and combustor

technologies have to be considered.