Propeller Open Water Characteristics in Waves

Paper in proceeding, 2022

The propulsion factors for ships when operating in waves deviate from those in calm water (Gerritsma et al. (1961), Moor and Murdey (1970) and Nakamura and Naito (1975)). Propeller-hull interaction effects are also different in waves compared to calm water. In order to map the differences in an ongoing research, the performance of a tanker ship in calm water and in regular head waves is being studied through the following steps:
 1. bare hull performance in terms of resistance, motions and nominal wake in a range of operational conditions,
 2. isolated effects of waves on performance degradation of the open water propeller,
 3. propeller-hull interaction effects in self-propulsion.

The main objective of this paper is to study the propeller open water (POW) performance in waves and compare it with calm water condition, representing step 2. To this end, a series of POW model tests are carried out in a towing tank for a range of regular head wave conditions. The propeller submergence is chosen to avoid propeller ventilation, while still being affected by the encountered waves. The tests are carried out for a series of advance ratios and wave steepnesses. The desired advance ratios are obtained by keeping the carriage speed constant and adjusting the propeller rotational speed. Numerical computations are also carried out for the same conditions using a Reynolds-Averaged Navier-Stokes (RANS) solver and validated against the model tests. The propeller characteristics including its thrust, torque and efficiency are studied. This paper presents the progress of the research and may be subjected to significant revisions.