Abstract:
To understand the sudden change in the lift coefficient of a thick crescent-shape iced conductor at a 15° angle of attack, numerical simulations were carried out using both the Reynolds Average Navier-Stokes (RANS) equations with the
k-
ω SST turbulence model and the large eddy simulation (LES), in a range of angles of attack from 10° to 20°, and the aerodynamic characteristics and flow fields were obtained. By comparing the aerodynamic coefficients, flow structures and surface wind pressure distributions computed from the two numerical methods, it is found that the LES performs better in modelling the small-scale vortex structures near the surface of the crescent-shape iced conductor. In addition, the LES results have higher accuracy and are highly consistent with the wind tunnel test data. However, the
k-
ω SST turbulence model fails to capture small-scale vortices on the surface as well as the sudden change in the lift coefficient. According to the pressure distribution on different surface areas of the iced conductor, it is found that the vortex structure on the upper wall affects the overall flow field, whereas the combined action of the lower wall surface curvature, the incoming flow angle and the wall tangent direction lead to the sudden change in the lift coefficient. The aerodynamic forces predicted from the LES results can provide a reference for anti-galloping measures of iced conductors.