This study conducts a simulation analysis on rocket nozzles, exploring variations in potential core length across over-expanded, under-expanded, and optimally expanded nozzles at Mach numbers ranging from 1–4, employing computational fluid dynamics (CFD) techniques. In the context of space vehicles, significant external pressure fluctuations are experienced during atmospheric propulsion system operation. These fluctuations primarily stem from turbulent mixing within the rocket exhaust flow, contributing to the acoustic field. A comparative analysis is conducted, juxtaposing simulation results with experimental data and referencing variations in potential core length documented in NASA SP8072. The findings reveal a strong correlation (87%) between properly expanded jets and experimental outcomes, indicating an increase in potential core length with rising Mach numbers. Remarkably, this study result also presents that under-expanded and over-expanded jets exhibit shorter potential core lengths compared to optimally expanded counterparts.