This work involves an experimental and computational examination of vacuum ejectors, specifically by varying jet velocities within a diffuser section through alterations in nozzle geometry. The study encompasses pressure escalation from ambient to 5 bar, unveiling pressure oscillations within the secondary chamber as the main flow pressure increases. Initially, minor pressure fluctuations occur, but upon reaching a critical primary jet pressure, the secondary pressure rapidly diminishes to an exceptionally low level. Subsequently, an increase in primary jet pressure corresponds to a rise in vacuum pressure. A computational domain replicating the experimental geometric configuration is established and validated using pressure sensors placed at various positions, aligning with experimental data. To explore the impact of varying jet velocity on secondary chamber vacuum pressure, the nozzle’s area ratio is adjusted. Four distinct cases are analysed through CFD analysis, involving Mach numbers 1.25, 1.5, 1.7 and 2. Comparative analysis indicates that as jet velocity increases, the maximum negative pressure achievable within the secondary chamber improves. Moreover, increased jet velocity prolongs the time required for the jet to attach to the diffuser walls, delaying the formation of dynamic recirculation bubbles and consequently impeding further evacuation.