Fluid-Structure Interaction of Propellers

The performance of a propeller is influenced by the wake of the ship, which results in an unsteady inflow to the propeller. Thus, the pressure on the propeller and its distribution as well as the resulting torque and thrust fluctuate during, a revolution. The se variations may evoke vibration of the propulsion system and it further transfer of the induced vibration into the hull structure can take place. For special purpose applications, e.g. cruise liners, fishing research vessels and submarines, vibration and the resulting noise level is a strong design criterion. In order to minimise pressure fluctuations, a propeller with a high blade number and skew angle is recommended. Beside the reduction of the noise level it is also an advantage to minimise the displacement effect by application of thin blade shapes. During the Calculation of the pressure fluctuation, the deformation of the propeller due to thrust loading is mostly neglected, but as the blades are thin, already at partial load, the dynamic structural reaction influences the flow around the propeller. As the pressure distribution changes, CFD calculations considering the deformation of the propeller become even more important.