With IMO’s EEDI requirements tightening, propellers for shallow-draft ships or ballast navigation often approach or pierce the free surface, inducing ventilation that degrades hydrodynamic performance. However, existing studies lack targeted analysis of the KP505 propeller—specifically designed for KCS container ships—across full operational advance coefficients \(J\) and optimized numerical setups. To address this gap, the incompressible RANS method coupled with the VOF model (HRIC scheme) was used in STAR-CCM + to simulate the KP505’s unsteady performance under ventilation. Grid validation followed ITTC guidelines, and numerical results were cross-validated against KRISO experimental data, ensuring the reliability of the simulation framework. Simulations across operational \(J\) ranges show that as \(J\) increases, propeller thrust and torque losses decrease significantly, while the corresponding loss coefficients gradually approach 1. At low \(J\) , high blade load causes severe free-surface piercing, chaotic wake structures, and uneven pressure distribution, with loss coefficients exhibiting periodic fluctuations correlated with the number of propeller blades. At high \(J\) , ventilation effects are mitigated, the free surface stabilizes into regular Kelvin waves, and the wake displays ordered conical dissipation, effectively reducing adverse impacts on propeller performance. This study clarifies the interaction mechanism between the KP505 propeller and the free surface under ventilation conditions, supplemented by insights into the optimization of numerical simulation parameters. The findings provide generalized benchmarks and actionable guidance for the design, operational optimization, and performance prediction of propellers in ballast or shallow-draft navigation scenarios, aligning with IMO’s energy efficiency requirements and contributing to the durability and efficiency of marine propulsion systems.
