Numerical simulation of aerodynamic performance of static airfoil of vertical axis wind turbines under icing conditions

Ice accretion on wind turbine blades poses a significant operational challenge in cold climates and high-altitude environments, leading to significant adverse effects on their performance. This paper employs numerical simulation method to analyze the effects of ice accretion on the NACA0018 airfoil, a common airfoil in vertical axis wind turbines. The results indicate that water droplet impact and ice accretion primarily concentrate near the airfoil's leading edge. Moreover, as the angle of attack (AoA) increases from 3° to 15°, the ice accretion on the upper surface remains confined within 6.4 % of the chord length, whereas the lower surface exhibits a more extensive ice coverage, reaching up to 18.3 % of the chord length. Following a 30-min icing period at a LWC of 2.32 g/m3, the iced airfoil experiences a substantial degradation in lift-to-drag coefficient ratio, exceeding 30 %. In addition, both clean and iced airfoils achieve their optimal lift-to-drag coefficient ratio at an AoA of 9°. As ice accumulates at the leading edge, the surface contour of the airfoil develops pronounced concave geometries, which in turn generate enlarged low-velocity regions near these concavities. The pressure coefficient curves along these irregular surfaces exhibit oscillations, indicative of increased aerodynamic instability.