Achievements

Air traffic is increasing by an average annual growth rate of around 5 per cent on a global scale. To reduce the environmental footprint LEMCOTEC is addressing in particular the emission targets of the ACARE 2020 Vision for CO2 reduction of minus 15 to 20% for the engine alone and for NOx-reduction of minus 60% for the combustion system alone, relative to the year 2000 datum.

LEMCOTEC is developing further core-engine technologies at sub-system and component level that allow operation at higher pressures and temperatures which are increasing the engine efficiency. The objective is to increase the compression system overall pressure ratio of up to 80% relative to the year 2000 datum.

Benefits are coming in through reduced weight of components and by application of improved materials with higher temperature capability, lower density and lower costs, depending on the component. The engine casings are designed for higher stiffness. The cooling air requirements of the hot structures and of the intermediate and high-pressure turbine will be reduced.

LEMCOTEC is a so-called LEVEL 2 integrated project validating the techno­logies developed further by component and full-scale sub-system tests at relevant test conditions. As such it is closing the gap between basic research and innovation actions (LEVEL 1) and pre-competitive technology demon­stra­tion in Clean Sky (LEVEL 3).

The LEVEL 2 projects, such as LEMCOTEC, are taking up promising technology concepts, which have proven their potential at basic research level, to mature them further and by integration into sub-system modules, which are tested and validated in large demanding rig tests.

LEMCOTEC validates core-engine technologies, which are needed for the future ultra-high overall pressure ratio (OPR) aero-engines. Depending on the complexity and confidence in successfully tested sub-system technologies these can be passed further to LEVEL 3 engine integration and demonstration like in Clean Sky or directly to commercial Engine Development Programmes. It can be expected that successful sub-system technologies can enter into service in 5 to 10 years after completion of the project.

In LEMCOTEC three generic study engine architectures have been defined to perform accurate assessments of the actual achievements. These generic study engines are representing regional, medium and long range applications.

Regional Turbofan

The small regional turbofan engine (Fig. 1) has an OPR of around 50:1. Because of its small size the compression system needs a centrifugal impeller stage to replace the last 4 rear stages of the axial high-pressure compressor to avoid low efficiencies from these stages. The architecture integrates a lean burn technology based on the PERM (Partially Evaporating Rapid Mixing) combustor concept with an advanced injection system aimed to meet the NOx targets for the high OPR cycle.

Figure 1: Regional Turbofan (RTF)

Mid-size Open Rotor

The Mid-size Open Rotor engine (Fig. 2) has an OPR of around 60:1 and is designed for a short/medium range mission. The propulsor archi­tecture consists of a contra-rotating geared drive pusher configuration. The engine is equipped with a MSFI (Multi-Stage Fuel Injection) lean com­bustion system with innovative fuel controls that will enable NOx reduction and allow for improved com­bustor-turbine interaction.

Figure 2: Mid-size Open Rotor (MOR)

 

Large Turbofan

The large thrust turbofan aero-engine (Fig. 3) is aim­ing at OPR 70:1. The engine integrates ad­vanc­ed core-engine modules and technologies in direct drive 3-shaft architecture.

It applies several new aerodynamic and mech­anical features on the Intermediate Pressure Com­pressor (IPC), High-Pressure Compressor (HPC), High-Pressure Turbine (HPT), advanced lean burn combustion systems based on LDI (Lean Direct Injection) technology and stiffer light-weight struc­tures.

Figure 3: Large Turbofan (LTF)

 

Tab.1 summarizes the corresponding aircraft design features for the RTF, MOR and LTF appli­ca­­tions. Maximum Take-off Weight (MTOW) is given in tons; range in nautical miles (NM).

Table 1: Design features of the underlying generic aircrafts

 

Mission

Regional

Short-medium

Long-range

Study Engine

RTF

MOR

LTF

PAX

100

150

270

Range (NM)

2000

3000

6500

MTOW (t)

50

82

230

 

 

 

Assessment of Improvements

The technologies developed include an improved centrifugal diffuser, improved mechanical and aerodynamic designs of IPC and HPC. The aim is to increase the compression system efficiency and stability, reduced size effects and less compressor dete­rio­ration. The expected compressor improvement for all three engine architectures is about +1%-point efficiency.

The development and testing of the three low emission combustor technologies is currently on-going. Tab.2 summarises the targets for the three study engines.  Percentages are defined with res­pect to year 2000 references for CO2 emissions and with respect to CAEP/2 limits for other gas­eous and particulate emissions.

Table 2: Reduction Targets

 

 

Datum

RTF

MOR

LTF

CO2

vs. Year 2000

20%

30%

24%

NOx

vs. CAEP/2

65%

70%

65%

CO

vs. CAEP/2

50%

50%

50%

UHC

vs. CAEP/2

50%

50%

50%

Smoke

vs. CAEP/2

75%

75%

75%

 

The results of a preliminary emissions and perfor­man­ce assessment are available. For the RTF both, the PERM and LDI style combustion sys­tems have been used in this preliminary assessment.

 

Table 3: Preliminary Reductions Achieved

 

 

Datum

RTF

MOR

LTF

CO2

Year 2000

19.0%

28.5%

23.4%

Injection System

LDI

PERM

MSFI

LDI

NOx

vs. CAEP/2

77%

63.2%

70.3%

66.1%

CO

vs. CAEP/2

79%

n/a

n/a

77.6%

UHC

vs. CAEP/2

87%

n/a

n/a

79.3%

Smoke

vs. CAEP/2

<75%

n/a

n/a

< 75%

 

These preliminary results are very encouraging (Tab. 3). For all three engine types the targets regarding CO2 emission reduction is almost met. It has to be noted that reductions of CO2, fuel burn and of emissions of sulfur oxides of petrol-based Kerosene are proportional.

The NOx reductions are larger than targeted and are exceeding the targets set. For the PERM and MSFI the CO, UHC and smoke emission tests and measure­ments have to be completed to get preli­minary numbers.

As the technology validations have progressed, the targets for compressor and turbine efficiencies, component weights, combustor emission indices, cooling needs and ducting pressure losses have been re-evaluated. Thus the experience from design exercises, flow and mechanical simulations and finally rig data has been used to feed back to the application engine design.  For the work on struc­tures and turbines the achieved results are shown in Table 4. For the compressor and combustor technologies the reference levels are set by corresponding targets.

Table 4: Turbines and Structures Achievements

 

Component

Target

Result

 LTF Intercase

+10% stiffness-to-weight

+11.4%

 MOR Intercase

-10% weight

-18%

 Intercase Material

+50 K capability

achieved

 Compressor OGV

-10% weight

+0.5% HPC efficiency

-40%

+0.35%

 HPC Rear Cone

+50 K capability

+30 K

 Combustor case Material

+50 K capability

-5% weight

on track

 Mid Turbine

 Frame Liner

-15% weight

-35% cooling air

-24%

-48%

 Turbine Shroud

-10% weight

on track

 HPT

+0.5% efficiency

-3% cooling

on track

 Inter Turbine Duct

-10% pressure loss

on track

 IPT

+1% efficiency

achieved

 

These data have been used to compile intermediate technology assessments, for which the ‘Technical Indicator’ (TI) method has been selected. The method was developed and successfully applied in previous research projects and has been adapted to LEMCOTEC. The TI analysis is based on whole system and mission trade functions for the module and subsystem characteristics.

The results from the assessment have been compared with a long and a short range mission of the ICAO Carbon Emissions Calculator (CEC) in Tab. 5. The corres­ponding datum air­crafts are repre­senting year 2000 technology. These are compared with assessment results for the same Y2000 air­craft, where their year 2000 technology engines were replaced by advanced LEMCOTEC technology aero-engines.

The short range mission is represented by a typical European route, i.e. from Berlin TXL to Brussels BRU with a distance of 642 km. The long range mission considers a typical transatlantic flight from Frankfurt FRA to New York JFK over a distance of 6,186 km. The CEC methodology considers both, the passenger load and passenger to freight factors when allocating CO2 emissions and fuel burn.

Fuel Consumption

Regional

CEC

Regional

LEMCOTEC

Transatlantic

CEC

Transatlantic

LEMCOTEC

Y2000 Datum

MOR

Assessment

Y2000

Datum

LTF

Assessment

 Fuel Burn FB

 [ kg ]

3,200

»2,240

54,240

»41,550

 CO2 / PAX

 [ kg ]

74.7

»52.3

424.3

»325

 FB / PAX / 100 km

 [ litres ]

4.5

»3.1

2.5

»2.0

 

Table 5: Comparison of Estimated Specific Fuel Consumption for

a European Regional and a Transatlantic Long Range Flight Mission

The conclusion is that LEMCOTEC technologies (engine alone) are driving the consumption towards 2 litres / PAX / 100 km (see Tab. 5). It can be estimated that together with the contributions from the other sectors (e.g. airframes, operations and air traffic manage­ment) 1 litre per 100 passenger kilo­me­tres is achievable in the long term.

Besides the environmental costs reduction by saving of emissions (CO2, SOX, NOX, CO, HC and soot) there is a direct economic impact on the operating costs. These costs savings are linked to the price of Kerosene and allow for a reduction of air fares and stimulate growth of air transport and air travel.

This will help the European industry to keep a competitive edge, maintain existing and develop new highly skilled jobs in research, development and manufacturing.

Beyond LEMCOTEC it is important that the instrument of LEVEL 2 integrated projects will be main­tained to ensure that technologies can be developed and validated at sub-system level. LEVEL 2 projects bridge the gap between Clean Sky and basic research innovation initiatives.

With LEVEL 2 projects technology integration and validation at the sub-system level will be addressed in European collaborative research project.

Besides ultra-high pressure core-engine (including IP/HP compressors, combustion system, HP/IP turbines, shafts and structures) development to enhance the thermal cycle efficiency, ultra-high bypass engine low-pressure spool systems (including fan system, LP turbine, exhaust system nacelle, bypass duct and fairings, thrust reverser units and nozzle) are required to maximise the propulsive efficien­cy. Advanced technologies for noise reduction at the source are required to increase the acceptance of aviation in the vicinity of airports. Advances in materials, manufacturing methods, controls and electrical system integration are enablers.

To support the technology development advanced design tools are required and have to be brought into application. The level of confidence in and accuracy of work benches which are applying multi-objective multi-disciplinary design tools have to be improved and validated. The advanced design tools have to be introduced into research and development to allow further reduction of the environmental footprint with the target to support the objectives set by Flight Path 2050, e.g. 90% NOX and 75% CO2 emission reduction by 2050 relative to year 2000 technology.

The results will be used in future aero engines, either directly through technology insertion into current Engine Development Programmes (EDP) or after engine integration and demonstration (e.g. Clean Sky) into future EDPs.

Aero-engine development is a highly complex task in which the LEMCOTEC partners shared risks in successful joint engine developments (e.g. IAE V2500, CFM56, TP400).

The exploitation of the LEMCOTEC technologies could take place by similar arrangements, by other risk and revenue sharing agreements or independently by the engine manufacturers together with a corresponding supply chain.

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