Numerical investigation of anti-icing in a wind turbine blade section using a swirling hot-air flow

This study presents a numerical investigation of a hot-air anti-icing concept for a wind turbine blade operating under cold-climate conditions. The system is based on the supply of swirling heated air into an annular channel located near the leading edge of a NACA 64-618 blade section representative of the NREL 5 MW rotor. A three-dimensional steady conjugate heat transfer model was developed in ANSYS Fluent using the k-ω SST turbulence model with curvature correction and temperature-dependent air properties. The parametric study included 250 simulations covering inlet air temperatures of 353–453 K, ambient temperatures of 263–271 K, mass flow rates of 0.05–0.10 kg/s, and swirl angles from 0° to 75°. The thermal feasibility criterion was defined as the leading-edge control-point temperature T 5 exceeding 273.15 K. This criterion was used as a necessary thermal condition for anti-icing operation, rather than as a complete prediction of ice accretion, droplet impingement, or runback-water freezing. The results show that swirl substantially improves internal convective heat transfer and expands the operating domain satisfying the adopted thermal feasibility criterion. However, the increase in outer surface temperature remains significantly smaller than the increase in channel-side wall temperature, indicating that heat conduction through the blade wall and external convective losses become limiting factors. Moderate swirl angles provide the best thermo-hydraulic efficiency, whereas strong swirl is more effective when the priority is to satisfy the thermal feasibility criterion near critical ambient temperatures. The obtained thermal feasibility maps can be used for selecting rational operating parameters of hot-air blade heating systems, while further ice-accretion modelling is required to assess droplet impingement, runback water, and local ice formation under real atmospheric icing conditions.