Exergy-Based Formulation for Aircraft Aeropropulsive Performance Assessment: Theoretical Development

Aircraft have evolved into extremely complex systems that require adapted methodologies and tools for an efficient design process. A theoretical formulation based on exergy management is proposed for assessing the aeropropulsive performance of future aircraft configurations. It consists of the combination of a momentum balance and a fluid flow analysis involving the first and second laws of thermodynamics. The exergy supplied by the propulsion system and its partial destruction within the control volume is associated with the aircraft mechanical equilibrium. Characterization of the recoverable mechanical and thermal outflows is made along with the identification of the irreversible phenomena that destroy their work potential. Restriction of the formulation to unpowered configurations yields connections to some well-known far-field drag expressions and shows that their underlying theory can be related to exergy considerations. Because the exergy balance does not rely on the distinction of thrust and drag, it is especially suitable for the performance evaluation of highly integrated aeropropulsive concepts like boundary-layer ingestion.