Influence of propeller tip roughness on tip vortex strength and propeller performance

This paper investigates the effects of propeller tip roughness on the tip vortex formation. The results show that sand grain roughness can lead to a significant drop in angular vortex momentum and therefore reduces the underpressure in the vortex core. Owing to additional viscous stresses between propeller blade and detached tip vortex, the momentum is transformed into turbulent kinetic energy. As the turbulent scales are dissipated partly, the energy content of the system is reduced. This effect shows to be sensitive to application area and roughness height.