Numerical assessment of surface roughness on a full scale propeller

Paper in proceeding, 2024

This work addresses the performance of a full scale propeller in an open water setup for varying roughness heights, obtained with a RANS solver and the k-omega SST turbulence model. The application of roughness is done with wall functions and by resolving the boundary-layer. Two cases are considered for the same propeller geometry, one with and another without the anti-singing edge on the propeller blades. Baseline simulations without roughness are performed as well, and grid refinement studies are carried out to estimate the numerical uncertainty. The results showed that the influence of roughness is weak if wall functions are not used, whereas a significant decrease in thrust and torque is obtained if roughness is applied in conjunction with wall functions. The inclusion of the anti-singing edge leads to an increase in thrust and torque, but decrease in efficiency for low advance coefficients. The region of separated flow near the trailing edge of the propeller caused by the anti-singing edge is influenced by the roughness height, and is absent in the geometry without the anti-singing edge.