Propeller–hull interactions and added power in head seas

Abstract

Accurate estimation of a surface vessel’s added power in waves is essential to ensure efficient and safe operations. Propeller–hull interactions play significant roles in added power and are dominated by viscous effects. Therefore, numerical simulations of added power require the use of a Navier–Stokes based solver to account for viscous effects. To reduce the computational cost, the propeller is often modeled using an actuator disk, and hybrid techniques can be employed using potential flow methods. However, such approximations may not capture the nonlinear and viscous propeller–hull interactions in waves. On the other hand, reduced-scale experiments of added power are complicated by scaling effects because the Reynolds number is typically several orders of magnitude lower than that for full scale, and the higher relative contribution of viscous effects at model scale leads to over estimation of the added power. The objective of this work is to study the role of propeller–hull interactions in waves, related scaling effects, and numerical challenges. The results show that added power is not simply a linear function of the added resistance or the incoming wave amplitude squared because of complex propeller–hull interactions in waves. Moreover, the over prediction of added power increases with smaller model size.