Reducing Installation Costs by Leaving Blades Unattended?iWind Renewables has provided technical consulting services addressing the assessment of aeroelastic instabilities on incomplete wind turbines (with one or two blades assembled) during installation or maintenance. A wide list of wind turbine configurations of rated power spanning from 2 to 6+MW was analysed, with short or tall, steel or concrete towers. Both mechanisms that potentially trigger aeroelastic instabilities were examined, i.e. stall- and vortex-induced vibrations, at all relevant rotor and tower modes. It was concluded that single- and two-bladed setups may be left unattended for a reasonable time (in the order of weeks) if properly designed and analysed, allowing for a reduction in installation costs. The methodology applied, demonstrative results and key parameters that affect stability are presented and discussed in this article.
By Dimitris Manolas and Panagiotis Chaviaropoulos, iWind Renewables, Greece
