Graphical exergy analysis for a scramjet thermodynamic performance evaluation

Graphical exergy analysis was applied to a scramjet at cruise conditions. A zero-dimensional scramjet model was developed to describe the thermodynamic process of a hypersonic propulsion system. Energy utilisation diagrams (EUDs) were drawn to present the relationship between energy and energy level at cruise conditions. Performance optimisation based on the exergy efficiency was completed ranging from Ma 5.35 to Ma 6.23. The results indicate that the exhausting process produces the most exergy destruction, then the combustion process, and the exergy loss in the expansion process is the smallest. There is a maximal exergy efficiency with the variation of fuel equivalence ratio for a certain entrance condition, and the maximum increases with the cruise Mach number and the altitude. The advantages of graphical exergy analysis, such as visual representation of the relationships among different components and the convenience of analysis, were also shown by the example in this paper.