This thesis presents an approach to evaluate the performance of low-bypass turbofan engines without afterburner for a low-boom supersonic aircraft operating at Mach 1.5. The proposed method focuses on optimizing the propulsive performance by minimizing fuel consumption while meeting mission profile requirements. The study contributes to the MORE&LESS project, providing methods for rapidly designing novel supersonic propulsion concepts with improved environmental performance. The research conducts a thermodynamic analysis for on-design engine conditions based on the Modified Specific Heat (MSH) gas model. Specific non-installed thrust and fuel consumption are estimated for cruise phase. Then, the engine cycle analysis is also performed to study off-design performance, including simplified models to account for engine drag and calculate installed thrust and fuel consumption.