Ships are prone to icing when navigating in polar low-temperature environments. Excessive ice accumulation can affect ship stability, operational safety, and operability of deck equipment, posing a serious threat to crew safety and hindering the rational development and utilization of polar regions. Ship icing is mainly caused by the splashing of waves, and its physical process can be regarded as the freezing process of a large number of saltwater droplets on a cold surface. Experimental research on the freezing process of a single saltwater droplet is essential for deeper understanding of the mechanism of ship superstructure icing at the mesoscale. For this, experiments are conducted on the freezing and melting of freshwater droplets on cold surfaces, the progress of the phase interface during the freezing process of freshwater droplets, the shape changes of water droplets after freezing, the freezing and melting time are recorded, and the influencing factors of the freezing process of freshwater droplets are analyzed. A saltwater droplet freezing experiment with a 3.5% mass fraction is also conducted, the shape changes, freezing and melting times after freezing are recorded, and the impact of droplet volume and cold surface temperature on the freezing process of the saltwater droplets are analyzed and discussed. The influence of salinity is analyzed and compared by comparing the freezing and melting experimental results of saltwater with those of freshwater droplets. The research outcome can provide data support for the validation of ship icing prediction models and scientific guidance for the development of anti-icing and deicing technologies on structural surfaces.

Airfoil sail propulsion technology is of increasing interest aiming at emission peak and carbon neutrality.The wind from the ocean can be used to push the ship forward with the help of a sail structure to achieve the goal of energy conservation and emission reduction, but it will also generate rolling moment on the hull. The combined random wind and wave loads put forward new challenges to the prediction of the dynamic stability of the sailing ships in the wave. For this reason, the dynamic stability under the combined wind and wave loads is studied by using the spectral analysis method and the time domain analysis method with consideration of multiple wind spectrum, wave spectrum, wind direction and wave direction. The spectral analysis method does not consider the system nonlinearity, while the time domain analysis method considers the nonlinearity of the rollrestoring stiffness. It is found that the wind spectrum has little effect on the dynamic stability of the target ship, while the wave spectrum has a greater effect on that than the wind spectrum. The nonlinearity of roll cannot be ignored for the case in the current study. The results can provide theoretical references for the study of the dynamic stability of the airfoil sail-assisted ship under the combined random wind and wave loads.

The ice load caused by the contact between the propeller and the sea-ice with different physical parameters will have different influences on the propeller and propulsion shafting. The study of the influence of the ice load on the shafting and the response of the shafting can provide suggestions for the design and arrangement of the propulsion shafting.The ice load on the propeller caused by the contact between the propeller and different physical parameters is calculated by using ANSYS/LS-DYNA based on the fluid structure interaction method, and then the variation of the ice load is analyzed. The obtained ice load is input into ABQUAS to calculate and analyze the stress and strain of the propulsion shafting under the corresponding ice load in order to get the response of the propulsion shafting. It shows that the dynamic response of the propulsion shafting is greatly affected by the ice load, which increases with the decrease of the radial distance of the sea-ice and the increase of the size and velocity of the sea-ice. Higher strength requirements are therefore demanded for the propulsion devices of ice ships.