Comparative study of grid validation methods for wind load computations of transmission lines

Strong unsteady aerodynamic forces are generated by severe flow separations around transmission lines, and galloping can be induced by this inherent motive force. Due to the severe flow separations around transmission line with blunt cross sections, transitions of boundary layers, and dissipations of vortex wakes, it is troublesome to calculate the wind load accurately. To account for the accurate computation of wind load for both single conductor and bundle conductor, comparative study of four different grid validation methods, including unsteady lift/drag forces, power spectral density (PSD) analysis of both lift/drag forces, wall shear stress on cylinder surface, unsteady turbulent kinetic energy in the flow field far down stream of the conductor cylinder, are conducted by solving Navier-Stokes equations. The results indicate that, it is feasible to employ the unsteady lift/drag force, PSD results of lift/drag forces to validate grid convergence of single conductor and wall shear stress is proposed to provide a more thorough insight into flow separation characteristics on cylinder surface; while besides the above three methods, the convergence of far field turbulent kinetic energy PSD results is as well proposed and then validated to be suitable for bundle conductors.