Comparison of self-propulsion performance between vessels with single-screw propulsion and hybrid contra-rotating podded propulsion

The present work compares the self-propulsion performance between vessels with single-screw propulsion and hybrid contra-rotating podded propulsion. The viscous flow fields of 4000 TEU container vessels with single-screw, single-rudder propulsion and hybrid contra-rotating propeller (CRP) podded propulsion systems were solved numerically by the Reynolds-averaged Navier-Stokes equations (RANS), the shear stress transport (SST) k. turbulence model, and the sliding mesh method. Numerical uncertainty analysis of the resistance and selfpropulsion factor were employed according to ITTC Quality Manual 7.5-03-01-01. Self-propulsion factor, viscous flow field, and pressure distribution at the stern of the vessels were analyzed in detail. Numerical results suggested that the vessel with the hybrid CRP podded propulsion showed a 17.59% larger effective wake fraction, a 40.2% smaller thrust deduction fraction, a 15.1% higher hull efficiency, and a 4.12% higher overall propulsive efficiency compared with the single-screw vessel. In addition, the vessel with the hybrid CRP podded propulsion showed a basically symmetric, smaller velocity gradient and more uniform flow field at the stern, resulting in a much smaller propeller-induced fluctuating pressure on the hull, compared with the single-screw vessel. In conclusion, the hybrid CRP podded propulsion system exhibited high efficiency and low vibration levels.