Unified Applicable Propulsion System Performance Metrics

Abstract

Progress in the development of electrical storage and conversion technology progressively attains focus in aerospace motive power research. Novel propulsion system concepts based on hybrid or even entirely electrical energy sources are seriously considered for aircraft design. To this point, unified figures of merit are required in order to allow for consistent comparative investigations of existing combustion engines and future electricallybased propulsion systems. Firstly, this paper identifies the shortcomings of conventional performance metrics used for nonthermal electrical conversion processes and then approaches exergybased loss methods as means of metrics extensions. Subsequently, energy sourceindependent figures of merit based on exergy analysis are derived and embedded into the wellknown performance definitions. Finally, the unified metrics are demonstrated through application to a conventional turbofan, a parallelhybrid turbofan, a novel integratedhybrid turbofan concept, and an entirely electrical fan concept.