Computational Analysis of Wind Energy Input into Overhead Power Lines: Turbulence

Alternate shedding of vortices from the top and bottom of a conductor in a flow of wind causes Aeolian vibrations in overhead lines. Energy transfer to the conductors are calculated using the energy balance method. Simulation of wind power input into a harmonically oscillating cylinder by a turbulent flow is solved by numerical integration of the Naiver-Stokes equations using a numerical simulation tool. The results show that the assumption of lock-in phenomenon has oscillatory behaviour at lower amplitude to diameter (A/d) ratios for forced cylinder motion. Numerical results are in good agreement in the laminar case and k-ω SST turbulent case with measurements. The relationship between cylinder motion and vortex shedding is unsteady resulting in lower power transfer to the cylinder. The vortex shedding frequency oscillates with 10% turbulent intensity and length scales of 25 mm, 50 mm and 75 mm.

Latitudinal Dependence of Wind-Induced Near-Inertial Energy

Midlatitude storms, accounting for the majority of wind energy input to near-inertial motions in the ocean, are known to shift their track significantly from one year to another. The consequence of such storm track shifts on wind-induced near-inertial energy (NIE) is yet unknown. Here, the latitudinal dependence of wind-induced NIE is first analyzed in the framework of the slab model and then tested using two numerical ocean models. It is found that the NIE input by pure inertial wind stress forcing, which dominates the wind energy input to near-inertial motions, is independent of latitude. As a consequence, the NIE generated by white-noise wind stress forcing is also latitudinally independent. In contrast, the NIE generated by red-noise wind stress forcing shows strong dependence on latitude owing to longer inertial periods at lower latitudes capable of sampling greater inertial wind stress forcing. Given that the observed surface wind stress spectra are red, results from this study suggest that an equatorward shift of the storm track is likely to result in an increase in wind-induced NIE in the ocean, while the opposite is true for a poleward shift.