Convergent-divergent nozzles are critical components in rocket and jet propulsion systems, designed to decelerate and de-pressure exhaust gases, thereby accelerating them to supersonic speeds and generating thrust. This study investigates the impact of convergent–divergent nozzle geometry on thrust performance through two-dimensional, compressible airflow simulations using Ansys Fluent. Two distinct nozzle geometries—one with a curved wall and another with an inclined wall—are analyzed. Flow characteristics are simulated under a constant inlet air temperature of 1200 K across five inlet pressure conditions: 5, 10, 15, 20, and 40 bar. The nozzle walls are assumed to be insulated, and the inlet, throat, and outlet cross-sectional areas are maintained consistently across both geometries. Simulation results indicate that the Mach number at the nozzle exit is consistently higher for the inclined-wall geometry compared to the curved-wall geometry, whereas the opposite trend is observed at the throat. With an increase in inlet pressure from 5 to 15 bar, the exit Mach number for both geometries shows a notable increase. However, beyond 15 bar, the exit Mach number plateaus, suggesting a saturation point. Thrust generation in both designs demonstrated a significant increase with rising inlet pressure. While the inclined-wall nozzle produced greater thrust at inlet pressures below 20 bar, the curved-wall nozzle exhibited superior thrust performance at the highest tested pressure of 40 bar.