Gust-front loading effects on wind turbine tower systems

With an increasing focus on the issues of extreme wind events, particularly thunderstorms and downbursts, it is important not to lose sight of their impact with regards to other industrial structures, which are themselves sensitive even to typical flow fields. For the treatment of conventional boundary layer winds, a gust loading factor approach has been widely adapted in most international codes and standards for the design of buildings. Wind turbine towers, though fundamentally different from buildings when viewed as a multi-body system featuring a tower/nacelle and blades, may be treated much in the same way with modified gust loading factors. This paper introduces a possible approach to mesh conventional treatments of gust loading factors with those of newly introduced gust-front factors on wind turbine towers. Much like gust-front factors for buildings, this approach encapsulates many of the varied kinematic and dynamic changes associated with nonstationary characteristics of gust-fronts originating from thunderstorms/downbursts and the changing aerodynamics on wind turbine towers. From an example of a wind turbine tower system, gust-front loading effects as compared to those of boundary layer winds are investigated.

► Gust-front loading effects on a wind turbine tower system are investigated.
► A gust-front factor framework for a wind turbine tower system is proposed.
► Gust-front loading effects are more significant than those in boundary layer winds.
► Kinematic effects of wind load by a nose-shaped wind profile are more prevalent.
► The second mode effects in a coupled wind turbine model are rather small.