The cavitation of a push-type ducted azimuth propulsor with the design target of balancing the large thrust under bollard condition and the required speed is numerically simulated under the maximum speed condition and the bollard conditions by using the Reynolds-Averaged Navier-Stokes (RANS) method with the SST k-ω model and Schnerr-Sauer cavitation model. The calculated cavitation pattern is generally in accordance with the experimental results. It captures the sheet cavitation on the back blade, the blade face cavitation, the tip-vortex cavitation and the tip-leakage cavitation. The propeller-hull vortex (PHV) cavitation is observed due to the close distance between the strut and the duct and ducted propeller. The correlation between the distance of the strut and the ducted propeller and the strength of the PHV is then analyzed to propose the distance that can suppress the generation of the PHV. The distance which is greater than 0.35D can basically eliminate the PHV. It provides an important support for the optimization design of the ducted azimuth propulsor based on the cavitation performance.

Submerged water-jet propulsion is a new development of traditional water-jet propulsion technology. The current study systematically analyzes the propulsion efficiency, the interaction between the hull and the water-jet and the specific speed of the propulsion pump based on the concept of this type of water-jet propulsion. It firstly establishes the mathematical modelling of the specific speed and the advance coefficient of the waterjet-propelled ship that are described by principal parameters of the hull and the propulsion system. The range of the speed and the specific speed of the propulsion pump for the submerged propulsion system has been demonstrated to reveal the mechanism of high efficiency. The variation of the main parameters of the propulsion system with the speed ratio and speed of revolution has been validated through case studies. It can provide a theoretical basis for the development and application of the submerged water-jet propulsion system.

Propeller is the core component of a ship. The performance of the propeller of an icebreaker is directly related to the speed/power performance, ice-breaking performance, vibration and noise performance and safe navigation performance of the whole ship. The design of the ice class propeller is therefore the key stage during the design of the icebreaker. It is necessary to ensure that the performance of the propeller can meet the design requirements. Different from the conventional propeller that operates in the open waters, the ice class propeller operates in the ice waters. The impact of the ice on the propeller should be considered during the design of the ice class propeller. However, there is little experience of the ice class propeller design in China. The ice class propeller design process (IPDP) has been established based on the analysis of the characteristics of the ice class propeller in the current study. The design results and model test results of the ice class propeller of a PC2 heavy icebreaker are presented. The results show that the design process of the ice class propeller is different from that of the conventional propeller with special focuses on the iterative design of the propeller parameters and hull parameters, due to the heavy load and multi-working conditions of the ice class propeller. It is necessary to verify not only the speed/power performance and vibration performance in the open waters, but also the speed/power performance and propeller strength performance in the ice regions. A detachable fixed pitch propeller is designed for the high ice class propeller to facilitate the repair and replacement of one single blade.