Print Email Facebook Twitter Coupled flap and edge wise blade motion due to a quadratic wind force definition Title Coupled flap and edge wise blade motion due to a quadratic wind force definition Author Van der Male, P. Van Dalen, K.N. Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 2014-03-31 Abstract The wind force on turbine blades, consisting of a drag and lift component, depends nonlinearly on the relative wind velocity. This relative velocity comprises mean wind speed, wind speed fluctuations and the structural response velocity. The nonlinear wind excitation couples the flap wise and edge wise response of a turbine blade. To analyze this motion coupling, an isolated blade is modelled as a continuous cantilever beam and corresponding nonlinear expressions for the drag and lift force are defined. After reduction of the model on the basis of its principal modes, the nonlinear response up to the second order is derived with the help of a Volterra series expansion and the harmonic probing technique. This technique allows for response analysis in the frequency domain, via which the combined flap and edge wise responses can easily be visualized. As a specific case, the characteristics of the NREL5 turbine blades are adopted. For both non-operating and operating conditions, blade responses in a turbulent wave field, based on a Kaimal spectrum, are determined. The second-order responses are shown to cause additional motion coupling, and moreover, are proven not to be negligible straightforwardly. To reference this document use: http://resolver.tudelft.nl/uuid:a3dcfee1-95e2-411b-aba1-b004b5770588 DOI https://doi.org/10.1088/1742-6596/524/1/012066 Publisher IOP Publishing ISSN 1742-6596 Source Journal of Physics: conference series 1, 524, 2014 Part of collection Institutional Repository Document type journal article Rights (c)2014 The AuthorsPublished under licence by IOP Publishing Ltd Files PDF Male.pdf 918.5 KB Close viewer /islandora/object/uuid:a3dcfee1-95e2-411b-aba1-b004b5770588/datastream/OBJ/view