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Low Emissions Core-Engine Technologies

Periodic Report Summary 2 - LEMCOTEC (Low Emissions Core-Engine Technologies)

Project Context and Objectives:
LEMCOTEC is an initiative that integrates the interests of all European aero engine manufacturers of the Engine-IMG and Europe’s leading research institutions and universities in the field of aeronautics providing innovative and sustainable technologies for the protection of the environment.
After laying the foundations for turbo-fan engines with very-high BPRs of up to 15 in VITAL and open-rotor configurations with ultra-high BPRs of 45 to 50 in DREAM, the development of core-engine technology with OPRs beyond 50 (up to 70 and higher), remains the only way, to increase the engine efficiency further, to expand the work commenced in NEWAC.
Global air traffic is forecast to grow at an average annual rate of around 5% in the next 20 years. This high level of growth makes the need to address the environmental penalties of air traffic all the more urgent. Consequently, Europe's aviation industry faces a massive challenge to satisfy the demand whilst ensuring economic, safe and more environmentally friendly air travel.
Current research is providing the technologies to improve the performance of existing engine components. However, even if these technologies enable improvements in emissions, their existing limitations (technology maturity and integration) might not allow the industry to reach the goals set by ACARE in the field of aeronautics research by 2020.

The main objective of LEMCOTEC will be to successfully validate, at component level (i.e up to TRL5), innovative ultra-high pressure-ratio core-engine technologies, to increase the thermal efficiency of the engine cycles relative to year 2000 in-service engines with
• OPR of up to 70 (at max. condition) as an enabler and key lever of the core-engine technologies to exceed the ACARE 2020 targets on CO2, NOx and other pollutant emissions:
• 20 to 30 % CO2 reduction at the engine level, exceeding both, the ACARE 15 to 20% CO2 reduction target for the engine and subsequently the overall 50% committed CO2 and the fuel burn reduction target (including the contributions from operations and airframe improvements),
• 65 to 70 % NOx reduction at the engine level (CAEP/2) to attain and exceed the ACARE objective of 80% overall NOx reduction (including the contributions from both, operational efficiency and airframe improvement),
• Reduction of other emissions (-50% CO, -50% UHC and -75% smoke/particulate matter at the engine level (CAEP/2), requiring that the minimum cruise combustion efficiency has to be higher than 99.8 %, exceeding the ACARE 2020 target for the reduction of other pollutants.
• Reduction of the propulsion system weight (engine including nacelle without pylon).

Project Results:
The following main achievements were made in the four LEMCOTEC RTD sub-projects:

Whole Engine specification and assessment on three study power plant concepts (SP1)
The subproject Whole Engine specification and assessment integrates the results for the LEMCOTEC technology developments in SP2, SP3 and SP4 into three study power plant concepts. This has been done by defining the engine requirements for a Regional turbofan equipped aircraft, a Medium Range Open Rotor equipped aircraft and a Long Range turbofan equipped aircraft.
Based on this the subproject has developed the engine platforms in terms of engine cycle main parameters, arrangements and dimensions to form overall specifications for three ultra high pressure ratio core engines. In the 2nd period, two intermediate assessments have been performed at MS2 and MS9 aiming at monitoring the project progress and preparing for the SP1 final project assessment. The selected assessment method is built upon Technical Indicators.
Additionally, concepts and evaluation methods for four innovative future cores aimed further into the future, i.e. 2030-2050 have been developed.

Ultra-high pressure ratio compressors (SP2)
Not provided by SP Leader despite frequent reminders

Lean combustion for ultra-high OPR engines (SP3)
The injection systems concepts issued from past projects have been analysed in order to identify the changes that must be brought to the design in order to meet the objectives in terms of Nox emissions and operability. 3D RANS and LES computations of several new designs have been performed to assess their capabilities and performance before manufacturing and tests in mono sector or multi-sector combustors. Because lean combustion is prone to combustion instabilities an innovative device for flame monitoring has been designed. A plasma ignition system is also considered and the corresponding test rig has been defined.
In parallel to the work devoted to the injection system, the design of the three combustion chambers has begun, and depending on the considered chamber is finished. Analyses of the cooling scheme and the external aerodynamics were performed, detailled design of the three combustors has been undertaken and for some partners have almost finished this activity. LES and pure acoustics computations have been performed in order to determine the minimum number of injection system for which the flame till propagate circumferentially after ignition and to identify the influence of fuel split against combustion instabilities. The overhaul sensitivity of the combustor to combustion instabilities one integrated into the engine, thus taking into account realistic boundary conditions at the high-pressure compressor exit and at the inlet of the high pressure turbine has been investigated. LES activities showed outstanding results with very good correlations with experimental datas. This will allows relying on more predictive calculation methodologies.
Moreover the design of the test rig aiming at the investigation by mean of optical and intrusive methods of the interface between the combustor outlet and the high-pressure turbine inlet was completed. Such tests were performed and give outstanding results as new measurement techniques – filtered Rayleigh scattering for example – were tested successfully. Some of the injections systems were tested as well and are being selected to be integrated in the annular chambers that will be tested at the final stages of the project.
Concerning full annular tests, the test plans are available and adaptations of tests rigs are in progress.
Finally, several architectures for the fuel control system that will be required in order to operate lean combustors into a real engine have been assessed and the specification for the ones that will be developed up to TRL5 within LEMCOTEC was consolidated. The design of such fuel control system was completed successfully for the first system and is almost finished for the second one. Both fuel control systems are in manufacturing stages and first tests should occur in the next few months.

Advanced structures and thermal management (SP4)
The sub-project Advanced structures and thermal management is developing 11 technology areas towards a medium TRL (4-5) demonstration level.
In the M19-M36 period, concept designs for products implementing the new technologies have been developed. In parallel with this, rig test articles and rig adaptations, as well as geometries for manufacturing trials have been designed.
The reference article for the intermediate compressor structure design for high specific stiffness has been tested in the mechanical (deformation) rig. The design for the improved compressor case has analytically been shown to give stiffness to weight exceeding the LEMCOTEC targets.
Heat treatment trials of extended temperature material for hot section structures have been performed.
Hot flow tests of Low leakage liner design and materials have been completed including transient temperature measurements. Assembly and structural integrity of the liner has been evaluated.
Modular tooling has been developed for laser assisted metal spinning in the Innovative forming process for hot section structure.
Also completed are the manufacture and tests of the intermediate pressure turbine, which are aiming for an increased efficiency design.
For other experimental tasks test and/or manufacturing trial hardware has been produced, rigs have been adapted and commissioned. Most of the purely analytical work is finished, with the exception of validations based on the experiments which are still in progress.
For inter-cooled and for recuperated engines concepts have designed and analytically shown to achieve and surpass the goals for fuel consumption reduction.

Potential Impact:
LEMCOTEC addresses the particular challenge in delivering the benefits of reducing CO2, NOx and other emmissions simultaneously, hence contributing to the attainment of the relevant ACARE targets described in their Strategic Research Agenda (SRA) and their Vision 2020.
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