Numerical research of the effects of fouling on the performance of marine propellers

Abstract

As it is known, propeller has been most widely-used ship thruster, propeller blade surfaces are of polished metal and have no antifouling provision, which makes them vulnerable to fouling. Under the effects of fouling, the propulsion efficiency of propellers decreases and fuel consumption of ships increases, thus greenhouse gas emissions increase, although the effects are rarely studied. The present work aims at quantifying the effects and providing a deep insight into the physical mechanism by means of Computational Fluid Dynamics (CFD) and the surface panel method. The simulation employs the SST k-ω turbulence model and is carried on NSRDC-NACA-66-mod blade section which is widely applied to marine propeller. Barnacles are selected as the study subject from the fouling community and are directly modeled at geometry level. With Propeller 4383 being studied, the induced velocity field under several advance coefficients through the surface panel method, hence the incoming velocity and effective attack angle of the blade sections at each radius are obtained. Then the lift and drag force of each blade section under fouling conditions are got through the CFD numerical method, and then the propeller open water performance parameters under fouling conditions are obtained through blade elements theory, such as the thrust coefficient TK, torque coefficient QK and open water efficiency η0. The results shows that the fouling has a serious adverse effect on the propeller performance parameters, and the serious calcareous fouling leads T_K goes down by 36.1%, Q_K increases by 25.7% and η₀ reduces by 49.2%.