NUMERICAL INVESTIGATION OF BIOFOULING ROUGHNESS IMPACT ON THE PERFORMANCE OF PROPELLER

Biofouling-induced surface roughness is a critical issue affecting the hydrodynamic performance of marine propellers, leading to increased energy consumption and emissions. This study investigates the effects of varying roughness heights on the thrust, torque, and open water efficiency of a B-series B4-70 marine propeller using Computational Fluid Dynamics (CFD). A wall-function-based roughness model was implemented within the RANS-SST turbulence framework to simulate realistic fouling scenarios while maintaining computational efficiency. The results demonstrate that surface roughness significantly decreases thrust and efficiency while increasing torque. At a roughness height of 500 µm, thrust losses reached up to 18% and efficiency dropped by nearly 2.5% at high advance coefficients, while torque increased by over 10%. These performance degradations are attributed to elevated wall shear stress and altered pressure distribution across the blade surfaces. The findings highlight the importance of maintaining clean propeller surfaces to reduce hydrodynamic losses, fuel consumption, and operational emissions in maritime applications.