Konstantinos G. Kyprianidis Department of Power and Propulsion, Cranfield University, Bedfordshire MK43 0AL, UK e-mail: k.kyprianidis@cranfield.ac.uk Tomas Grönstedt Department of Applied Mechanics, Division of Fluid Dynamics, Chalmers University of Technology, Gothenburg 41296, Sweden e-mail: tomas.gronstedt@chalmers.se S. O. T. Ogaji e-mail: s.ogaji@cranfield.ac.uk P. Pilidis e-mail: p.pilidis@cranfield.ac.uk R. Singh e-mail: r.singh@cranfield.ac.uk Department of Power and Propulsion, Cranfield University, Bedfordshire MK43 0AL, UK Assessment of Future Aero-engine Designs With Intercooled and Intercooled Recuperated Cores Reduction in CO 2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction in engine nacelle drag and weight. Conven- tional turbofan designs, however, that reduce CO 2 emissions—such as increased overall pressure ratio designs—can increase the production of NO x emissions. In the present work, funded by the European Framework 6 collaborative project NEW Aero engine Core concepts (NEWAC), an aero-engine multidisciplinary design tool, Techno-economic, En- vironmental, and Risk Assessment for 2020 (TERA2020), has been utilized to study the potential benefits from introducing heat-exchanged cores in future turbofan engine de- signs. The tool comprises of various modules covering a wide range of disciplines: engine performance, engine aerodynamic and mechanical design, aircraft design and performance, emissions prediction and environmental impact, engine and airframe noise, as well as production, maintenance and direct operating costs. Fundamental perfor- mance differences between heat-exchanged cores and a conventional core are discussed and quantified. Cycle limitations imposed by mechanical considerations, operational limitations and emissions legislation are also discussed. The research work presented in this paper concludes with a full assessment at aircraft system level that reveals the significant potential performance benefits for the intercooled and intercooled recuperated cycles. An intercooled core can be designed for a significantly higher overall pressure ratio and with reduced cooling air requirements, providing a higher thermal efficiency than could otherwise be practically achieved with a conventional core. Variable geometry can be implemented to optimize the use of the intercooler for a given flight mission. An intercooled recuperated core can provide high thermal efficiency at low overall pressure ratio values and also benefit significantly from the introduction of a variable geometry low pressure turbine. The necessity of introducing novel lean-burn combustion technol- ogy to reduce NO x emissions at cruise as well as for the landing and take-off cycle, is demonstrated for both heat-exchanged cores and conventional designs. Significant ben- efits in terms of NO x reduction are predicted from the introduction of a variable geometry low pressure turbine in an intercooled core with lean-burn combustion technology. DOI: 10.1115/1.4001982 1 Introduction Public awareness and political concern over the environmental impact of civil aviation growth predicted at 5.9% per year in 2007 1 has improved substantially during the past 30 years. As the environmental awareness increases, so does the effort associ- ated with addressing NO x and CO 2 emissions by all the parties involved. In the Vision 2020 report 2 made by the Advisory Council for Aeronautical Research in Europe on European aero- nautics, goals are set to reduce noise and emissions produced by the ever increasing global air traffic. Emissions legislation, set by the International Civil Aviation Organisation ICAO and its Com- mittee on Aviation Environmental Protection CAEP, is becom- ing ever more stringent, creating a strong driver for investigating novel aero-engine designs that produce less CO 2 and NO x emis- sions. On the other hand, airline companies need to continuously re- duce their operating costs in order to increase, or at least maintain, their profitability. This introduces an additional design challenge as new aero-engine designs need to be conceived for reduced environmental impact as well as direct operating costs. Decision making on optimal engine cycle selection needs to consider mis- sion fuel burn, direct operating costs, engine and airframe noise, and emissions and global warming impact. A tool following a Techno-economic, Environmental and Risk Assessment TERA approach is required to conceive and assess engine designs with minimum environmental impact and lowest cost of ownership in a variety of emissions legislation scenarios, emissions taxation poli- cies, fiscal and air traffic management environments. Within the European collaborative project enVIronmenTALly friendly aero-engines VITAL3, key low pressure spool tech- nologies for three different turbofan architectures are being inves- tigated, targeting step reductions in engine CO 2 and noise emis- sions. As part of the VITAL effort, a number of universities cooperate on establishing a platform for multidisciplinary system analysis, the TERA2020 environment. The tool is targeted toward identifying an appropriate design space where more complex and time-consuming tools could be utilized; it is capable of evaluating the technology progress achieved within the project on engine/ aircraft system level as well as performing scenario studies of next generation turbofan engines. The activities within the VITAL project specifically target year 2020 entry into service EIS, thus the acronym TERA2020. Contributed by the International Gas Turbine Institute IGTI of ASME for pub- lication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received April 7, 2010; final manuscript received April 11, 2010; published online September 14, 2010. Editor: Dilip R. Ballal. Journal of Engineering for Gas Turbines and Power JANUARY 2011, Vol. 133 / 011701-1 Copyright © 2011 by ASME Downloaded 27 Jan 2012 to 129.16.64.125. Redistribution subject to ASME license or copyright; see http://www.asme.org/terms/Terms_Use.cfm