Numerical Investigation of a General Cargo Vessel Wake in Waves

Övrigt konferensbidrag, 2019

Since calm water is rather an exception at an actual sea, optimizing propulsive efficiency of ships operating in more realistic environmental conditions than calm water has been gaining more attention recently. The effects of waves on propeller performance have been investigated by different researchers such as Taskar et al. (2016) who studied different influencing factors in terms of cavitation, pressure pulses and efficiency on propeller performance of KVLCC2. Since excessive wake variation in waves may have a significant impact on the propeller performance, it is important to study dynamics of the wake field for ships operating in waves. 

Although the propeller designers consider experienced-based margins for propellers operating in waves and off-design conditions, the knowledge of the wake field at different wave conditions for each specific hull could be beneficial in designing more efficient propeller. In this study, a general cargo vessel incorporating a Large Diameter Propeller (LDP) with a very small tip clearance is considered. In an earlier investigation, the authors of the current paper have carried out a study, Irannezhad et. al. (2019), on the propeller emergence risk assessment of the LDP vessel employing a potential flow panel code, SHIPFLOW Motions, as well as a viscous flow solver, STAR-CCM+. The aim of this paper is to first validate the LDP vessel computed heave and pitch motions as well as its resistance due to regular head waves in model scale against the experimental data, then to analyze the time-varying wake field and compare it in different wave conditions in the viscous flow solver. The propeller is not modeled in the simulations.