Assessment of Future Aero-engine Designs With Intercooled and Intercooled Recuperated Cores

Abstract

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. Conventional 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, Environmental, and Risk Assessment for 2020 (TERA2020), has been utilized to study the potential benefits from introducing heat-exchanged cores in future turbofan engine designs. 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 performance 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 technology 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 benefits 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.

Progress in Gas Turbine Performance

“…The cycle optimization results for the two powerplants are given in Table 2. Significant block fuel benefits are projected for the intercooled core engine, but they are smaller than those predicted in previous efforts [7]. This is mainly attributed to a minimum blade height requirement setting a practical lower limit on the intercooled core size for a given OPR.…”

Future Aero Engine Designs: An Evolving Vision

“…More details on these studies can be found in Kyprianidis et al (2011) and Larsson et al (2011). For the intercooled core assessment, a year 2020 Entry Into Service (EIS) turbofan engine with a conventional core was set up as the baseline.…”

On Intercooled Turbofan Engines

“…The prediction of engine performance, aircraft design and performance, direct operating costs and emissions for the concepts analysed in this study was made using the code described in [6]. Another code described in [7], was also used for carrying out the mechanical and aerodynamic design in order to derive engine component weights and dimensions. The two tools have been integrated together within an optimizer environment as illustrated in Fig.…”

“…The thermal efficiency benefits from intercooling have been well documented in the literature -see for example [2,3,7,9,[11][12][13]15]. Very little information is available however, with respect to design space exploration and optimisation for minimum block fuel at aircraft system level.…”

“…Very little information is available however, with respect to design space exploration and optimisation for minimum block fuel at aircraft system level. Previously, a comparative study was presented focusing on a conventional core and an intercooled core turbofan engine for long range applications [5,7]. Both configurations had the same fan diameter and were designed to meet the same thrust requirements.…”