A numerical study on the influence of crossflow transition on a marine propeller in open water

This work studies the influence of crossflow transition modelling on the performance and flow field of a controllable pitch propeller. The simulations are performed for two different crossflow terms, and baseline simulations without crossflow transition are performed as well. The results show that in the absence of a crossflow term, the flow over the propeller blades is almost fully laminar. When a crossflow term is included, a significant part of the flow becomes turbulent, thus causing a decrease in the thrust and torque coefficients. The change in the propeller performance is also due to the absence of laminar flow separation near the trailing edge, which is prevented when transition occurs upstream of that location due to crossflow. The comparison between the two crossflow terms shows that one always leads to a larger extent of turbulent flow and earlier transition than the other, although this not always translates in lower thrust and torque, depending on the considered advance coefficient. This illustrates the delicate balance in the effects taking place on the pressure and suction side of the propeller blades, and the importance of correctly including crossflow effects in simulations of model-scale propellers.