Numerical investigation of the surface roughness effect on the aerodynamic and aeroacoustic performance of a propeller

This study investigates the effects of surface roughness on the aerodynamic and acoustic performance of propellers, employing CFD techniques with RANS equations. Considering boundary layer development with roughness conditions, the analysis derived the aerodynamic and noise performance of a rotating propeller. For aeroacoustics, both Proudman’s formula and Ffowcs Williams-Hawkings (FW-H) acoustic analogy were used. As the numerical results provide insights into the trade-offs between aerodynamic efficiency and noise reduction, this study applied different roughness configurations to the blade and the effects were compared. Through a parametric study with various configurations, three optimal surface conditions were identified, achieving tonal noise improvements up to 2 dB at blade passing frequency, despite reductions in aerodynamic efficiency by 2% with condition Opt.3. Taking further into account operating duty, i.e. thrust of the propeller, angular velocity of the proposed model was adjusted, and the results were compared in detail. By applying rough conditions onto blade surfaces with selected roughness configuration, improvements in thrust performance could be achieved with Opt.1 and thus the reduced angular velocity for intended operating duty could make noise reduction by 1.5 dB at blade passing frequency.