With the advancement of science and technology, wind power generation has been widely adopted globally. However, ice accretion severely limits the operational efficiency and structural safety of wind turbines in cold regions, while existing research primarily focuses on the impact of supercooled droplets on blade icing, the influence of ice crystals in cold environments on the blade icing process has been largely overlooked. This study systematically simulated the accretion of ice crystals and supercooled droplets under clear ice conditions. It evaluated the effects of various ice crystal parameters on the icing process using Fensap-Ice, which is an advanced icing simulation tool. The results indicate that ice accretion, driven by the combined action of ice crystals and supercooled droplets, weakened ice corners, making the ice shape smoother and fuller. When the angle of attack of the ice-covered airfoil exceeded 15°, a separating vortex formed on the suction side of the blade, leading to a reduction in the lift coefficient. The findings of this study highlight the critical role of ice crystals in the icing process and provide a scientific foundation for understanding the icing mechanism under complex meteorological conditions.

This study presents numerical simulations of ice crystal accretion on aircraft surfaces under mixed-phase icing conditions, where ice crystals coexist with supercooled water droplets. The Finite Element Navier–Stokes Analysis Program (FENSAP-ICE) suite, incorporating the Discrete Roughness Optimization Program in 3D (DROP3D) and Ice Accretion Simulation in 3D (ICE3D) solvers, was applied to the Common Research Model with Natural Laminar Flow (CRM-NLF) to examine the effects of crystal size, aspect ratio, and concentration on ice growth. The results show that the presence of ice crystals produces smoother, more uniform, and substantially thicker ice compared with droplet-only cases, where distinct horns and roughness dominate. At peak growth locations, the predicted ice thickness increases by up to 75% under mixed-phase conditions. Quantitative analyses reveal that increasing crystal diameter from 50 μm to 200 μm raises ice growth by 25%–75%, increasing aspect ratios from 0.05 to 1 increases growth by 20%–75%, and raising concentrations from 0.25 to 2 kg/m³ enhances growth by nearly 450%. These findings demonstrate the critical role of ice crystals in promoting layered ice accumulation, clarify the mechanisms driving mixed-phase icing, and provide theoretical guidance for advancing anti-icing and de-icing technologies in aviation.

In cold environments, droplet freezing and ice accretion can significantly deteriorate the aerodynamic performance of wind turbine blades, while also inducing additional loads and operational safety risks. To support the efficient and stable design of anti-icing surfaces, this study proposes a simulation-data-driven optimisation method for micro/nanostructural parameters.First, a numerical model of droplet impact on hydrophobic microstructured surfaces was established based on CFD. A single-factor analysis and an improved particle swarm optimisation algorithm were combined to optimise the microstructure's geometrical dimensions. Subsequently, the optimised micro/nanostructures were fabricated on aluminium alloy surfaces via laser sintering. Droplet impact tests, abrasion tests, freezing adhesion tests, and low-temperature icing tests were conducted to evaluate the dynamic wettability, mechanical durability, and anti-icing performance of the fabricated surfaces. The results demonstrate that the optimised hydrophobic micro/nanostructured surface effectively suppresses droplet spreading and maintains stable interfacial regulation capability under different Weber numbers and droplet sizes. Durability tests further showed that the maximum spreading factor increased only slightly after repeated sandpaper abrasion. This result indicates good mechanical stability and the ability to maintain a Cassie state. At -10 °C, the frozen-droplet detachment force on the hydrophobic micro/nanostructured surface decreased to 0.2 N, indicating that the proposed micro/nanostructure could effectively weaken ice adhesion and exhibit favourable icephobic performance. The subsequent icing tests further confirmed that the hydrophobic micro/nanostructured surface effectively inhibited ice-layer formation and the propagation of ice accretion. The proposed hydrophobic micro/nanostructure design strategy provides a feasible approach for developing anti-icing engineering surfaces in cold environments.