A Work Transfer Perspective of Propulsion System Performance

This paper suggests an approach to analysis of propulsion system performance that focuses entirely on thermodynamic work potential (and loss thereof) as a universal basis for gauging engine performance. This work potential may take a variety of forms, including conventionally known exergy analysis. Emphasis is placed on understanding how work potential initially stored in the chemical bonds of the fuel is manifested as useable work potential in an engine, transferred through a collection of components organized as a propulsion system, and ultimately yields useful thrust work. A model for overall propulsion system efficiency is suggested to facilitate the analysis. Component work transfer functions are introduced as a tool for analyzing work transfer and are used in conjunction with standard methods of block diagram algebra. This analysis reveals the fundamental parameter groupings governing propulsion system thermodynamic performance and makes clear how work is transferred thorough various portions of the engine.