This study explores the influence of angle of attack (AOA) on the icing distribution characteristics of asymmetric blade airfoil (DU97) surfaces for wind turbines under icing conditions by numerical simulation. The findings demonstrate a consistence between the simulated ice shapes and experimental data. The ice thickness distribution on the lower surface of the leading edge exhibits a trend of first rising and then declining along the chord direction while showing a gradually decreasing trend on the upper surface. The ice distribution range on the upper surface of the trailing edge is broader than that on the lower surface. The peak ice thickness at the trailing edge rises significantly as AOA increases from 5° to 10°, and at the leading edge raises dramatically at droplet sizes of 30–40 μm and wind speeds of 5–10 m/s. The peak ice thickness is more significantly influenced by AOA than by ambient temperature due to the combined effect of airflow characteristics induced by AOA and latent heat (phase change) and sensible heat (thermal convection and thermal radiation) caused by ambient temperature. The findings offer valuable insights into the flow and heat transfer physics, and can operate as references for wind turbine anti/de-icing technology.

To investigate the temperature effect on characteristics of icing distribution near the tip part of rotating blade of large-scale horizontal-axis wind turbine, numerical simulations were carried out on a horizontal-axis wind turbine rotor with rated power of 1.5 MW based on a quasi-three-dimensional computational method developed in this study. The icing simulation was focused on the part between blade tip and 30% length of blade from tip along span wise to blade root where the most serious icing area is according to the past researches. Eight sections along blade were selected, and the ice accretion on each airfoil was calculated. Eight temperature values from −6°C to −20°C were decided to investigate the effects of temperature on icing under the certain liquid water content and medium volume droplet. Three icing times were selected to research the ice accretion on blade surface with the increase in the time. According to the results, the icing distribution has the overall characteristics that the icing shape changes from horn icing shape to streamline icing shape with decrease in the temperature. The closer the blade airfoil section to blade tip, the more obvious the ice accretion is. This study can be a reference for the research on anti-icing and de-icing technologies for large-scale horizontal-axis wind turbine.

Wind turbines in cold and humid regions face significant icing challenges. Heating is considered an efficient strategy to prevent ice accretion over the turbine’s blade surface. An ice protection system is required to minimize freezing of the runback water at the back of the blade and the melting state of the ice on the blade; the law of re-freezing of the runback water is necessary for the design of wind turbine de-icing systems. In this paper, a wind tunnel test was conducted to investigate the de-icing process of a static heated blade under various rime icing conditions. Ice shapes of different thicknesses were obtained by spraying water at 5 m/s, 10 m/s, and 15 m/s. The spray system was turned off and different heating fluxes were applied to heat the blade. The de-icing state and total energy consumption were explored. When de-icing occurred in a short freezing time, the ice layer became thin, and runback water flowed out (pattern I). With an increase in freezing time at a low wind speed, the melting ice induced by the dominant action of inertial force moved backward due to the reduction in adhesion between the ice and blade surface (pattern II). As wind speed increased, it exhibited various de-icing states, including refreezing at the trailing edge (pattern III) and ice shedding (pattern IV). The total energy consumption of ice melting decreased as the heat flux increased and the ice melting time shortened. At 5 m/s, when the heat flux was q = 14 kW/m², the energy consumption at E_A at t_δ = 1 min, 5 min, and 7 min were 0.33 kJ, 0.55 kJ, and 0.61 kJ, respectively. At 10 m/s, when the heat flux was q = 14 kW/m², the energy consumption at E_A at t_δ = 1 min, 3 min, and 5 min were 0.77 kJ, 0.81 kJ, and 0.80 kJ, respectively. Excessive heat flow density increased the risk of the return water freezing; thus, the reference de-icing heat fluxes of 5 m/s and 10 m/s were 10 kW/m² and 12 kW/m², respectively. This paper provides an effective reference for wind turbine de-icing.