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- Kyprianidis, Konstantinos, et al.
(author)
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Assessment of Future Aero-engine Designs With Intercooled and Intercooled Recuperated Cores
- 2011
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In: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 0742-4795 .- 1528-8919. ; 133:1
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Journal article (peer-reviewed)abstract
- Reduction in CO2 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 CO2 emissions—such as increased overall pressure ratio designs—can increase the production of NOx 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 NOx 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 NOx reduction are predicted from the introduction of a variable geometry low pressure turbine in an intercooled core with lean-burn combustion technology.
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| 2. |
- Zachos, Pavlos K., et al.
(author)
-
A sub-idle compressor characteristic generation method with enhanced physical background
- 2011
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In: Journal of engineering for gas turbines and power. - : ASME International. - 0742-4795 .- 1528-8919. ; 133:8
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Journal article (peer-reviewed)abstract
- Sub-idle is a very challenging operating region as the performance of a gas turbineengine changes significantly compared with design conditions. In addition, the regulationsfor new and existing engines are becoming stricter and the prediction of enginerelight capability is essential. In order to predict the performance of an engine, detailedcomponent maps are required. The data obtained from rig tests are insufficient at lowspeeds, creating the need for generation of maps within the sub-idle regime. The first steptoward this direction is the use of an extrapolation process. This is a purely mathematicalprocess and the results are not usually of sufficient accuracy. In addition, this methoddoes not provide any insight on the physical phenomena governing the operation of thecompressor at low speeds. The accuracy of the resulting compressor map can be increasedwith a better low speed region definition; this can be achieved via the thoroughstudy of a locked rotor compressor, enabling the derivation of the zero rotational speedline and allowing an interpolation process for the generation of the low speed part of thecharacteristic. In this work, an enhanced sub-idle compressor map generation techniqueis proposed. The suggested methodology enables the generation of characteristics at faroff-design conditions with enhanced physical background. Alternative parameters formap representation are also introduced. Provided that the all the blade rows of thecompressor are of known geometry, a numerical analysis is used for the calculation of thecharacteristic of the half stage and a stage stacking method is employed to create theentire compressor characteristic. This way, the sub-idle region of the map can be calculatedthrough interpolation, which provides a more accurate and predictive technique.Application of the method for compressor map generation showed that the proposedinterpolation approach is robust and capable of enhancing any performance simulationtool used for the prediction of transient altitude relight or ground-starting maneuvers.
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