Rotating machinery in cold and humid regions is prone to icing. For exploring the characteristics of icing on objects rotating around a vertical axis, such as vertical axis wind turbines (VAWT), a cylinder rotating around the vertical axis was selected as the research object in this study. Three cylinders with different diameters were selected, and icing tests carried out under different tip speed ratios (TSR) in a self-built icing wind tunnel. The icing characteristics were quantitatively analyzed using characteristic parameters, including the icing area, the dimensionless icing area, the stagnation point thickness and the dimensionless stagnation point thickness. The dimensionless stagnation point thickness decreased with increases in the diameter of the cylinder. The icing limit decreased with an increase in the rotational speed of the cylinder, and reached 50% under the high TSR condition. Various icing characteristics were also analyzed for two rotation modes: rotation around the vertical axis and around the horizontal axis. The research findings in the present study lay the theoretical and experimental foundations for exploring VAWT icing in depth.

When the offshore device, such as an offshore wind turbine, works in winter, ice accretion often occurs on the blade surface, which affects the working performance. To explore the icing characteristics on a microscale, the freezing characteristics of a water droplet with salinity were tested in the present study. A self-developed icing device was used to record the icing process of a water droplet, and a water droplet with a volume of 5 μL was tested under different salinities and temperatures. The effects of salinity and temperature on the profile of the iced water droplet, such as the height and contact diameter, were analyzed. As the temperature was constant, along with the increase in salinity, the height of the iced water droplet first increased and then decreased, and the contact diameter decreased. The maximum height of the iced water droplet was 1.21 mm, and the minimum contact diameter was 3.67 mm. With the increase in salinity, the icing time of the water droplet increased, yet a minor effect occurred under low temperatures such as −18 °C. Based on the experimental results, the profile of the iced water droplet was fitted using the polynomial method, with a coefficient of determination (R²) higher than 0.99. Then the mathematical model of the volume of the iced water droplet was established. The volume of the iced water droplet decreased along with temperature and increased along with salinity. The largest volume was 4.1 mm³. The research findings provide a foundation for exploring the offshore device icing characteristics in depth.

Ice accretion on the cold airfoil blade surface, such as wind turbines working in winter, affects its performance and degrades its aerodynamic characteristics and efficiency. Therefore, it is necessary to study the icing characteristics on the cold blade surface. At present, many pieces of research on wind turbine blade icing have been explored on the macroscale but seldom on the microscale. In this chapter, the icing process of a single water droplet on the cold aluminum plate surface was examined by a visualized method. The effects of volume and temperature on the icing characteristics were tested and acquired. After that, the profile parameters of iced water droplets were drawn and analyzed by MATLAB software, including the contact diameter, the maximum diameter and height of iced water droplets, the contact angle, and so on. The research findings provide experimental and theoretical foundations to deeply study the icing characteristics of wind turbine blades on a microscale.