Exergy analysis is used to evaluate the efficiency of a turbojet engine over an entire flight (including climb, cruise and descent), and to assess the sensitivity of these results to the selection of the reference environment. This study is an extension of previous work where the accuracy of an exergy analysis of a turbojet engine is evaluated for different reference environments on an instantaneous basis. The present work evaluates cumulative engine efficiencies. The results show that the use of a constant reference environment set at cruise altitude conditions yields cumulative exergy efficiencies that are within 0.01 % of those found using a variable reference environment (equal to the operating environment conditions at all times) over a 3500 km flight. This result is in contrast to the use of a constant sea-level reference environment where such are 3.7 %. This significant cumulative efficiency difference with the choice of reference environment is not observed when using an instantaneous exergy analysis. Care must be exercised when using a constant reference environment, as for both constant sea level and cruise-altitude reference environments cumulative rational efficiencies increase over the majority of the flight, whereas for a continuously varying reference environment these efficiencies decrease.
Exergy analysis of a turbojet engine over a complete flight cycle
Exergieanalyse eines Turbinenluftstrahltriebwerks über einen kompletten Flugzyklus
2001
8 Seiten, 2 Bilder, 1 Tabelle, 21 Quellen
Conference paper
English
Anflug , Augenblickswert , Bezugswert , Exergie , Flughöhe , Luftfahrt , Start , Turboluftstrahltriebwerk , Umwelteinfluss , Zyklus
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