New Principles for Dynamic Aircraft Exergy Mapping

As fuel efficiency becomes a greater concern in commercial aircraft design and operation it is important to gain a deeper understanding of energy use throughout an aircraft's systems. To meet this need, a new methodology is being developed that proposes the use of exergy as a metric for mapping the energy flows throughout an aircraft at any required level of detail over a given flight. Exergy allows direct comparison of differing energy types and clearer interpretation of losses and availability. Time-variant application of exergy to vehicles, however, presents complexities, such as large data volumes, temporary exergy storage, exergy exchange between system and mass, and an inconsistent reference state. A software tool prototype is introduced to allow the management of an aircraft exergy map. To describe its use an unmanned aerial vehicle is evaluated. A turbojet study isolates the reference state problem and illustrates the need to use a moving, aircraft-fixed reference state. However, it is shown that this does not eliminate the problem entirely because of the existence of exergy storages.