Hollow-cone nozzles are widely employed in thermal engineering and industrial spray systems, including gas cooling, dust suppression, humidification, and spray-based heat and mass transfer processes. Their performance strongly depends on the internal flow structure, particularly the formation of a stable air core and the resulting liquid film responsible for atomization. This study presents an investigation of the hydrodynamic characteristics of hollow-cone nozzles with different geometric configurations using Computational Fluid Dynamics (CFD), supported by experimental validation of additively manufactured prototypes. Three nozzle variants differing in the inlet channel and outlet orifice diameters were designed and fabricated using stereolithography (SLA). Numerical simulations were performed in ANSYS Fluent employing the Volume of Fluid (VOF) multiphase model to analyse the internal flow, air-core formation, pressure distribution, velocity fields, and spray development. The numerical results were validated through laboratory measurements of flow-rate characteristics and visual observations of spray formation over a pressure range of 0.25–5 bar. The results demonstrate that the relationship between the inlet channel dimensions and the outlet orifice diameter has a significant influence on the hydrodynamic behaviour of hollow-cone nozzles. An appropriate geometric configuration promotes the formation of a stable air core, enhances swirl intensity, and improves spray stability, resulting in higher hydraulic performance. The CFD model accurately reproduced the experimentally observed spray structure and flow characteristics, confirming its capability to predict nozzle performance. Good agreement between numerical and experimental results validates the adopted modelling approach and demonstrates the suitability of additively manufactured prototypes for rapid verification of CFD-based nozzle designs. The proposed methodology provides an efficient framework for the design and optimisation of hollow-cone nozzles intended for thermal engineering and industrial spray applications, reducing development time and prototyping costs while improving the understanding of complex two-phase flow phenomena.