The goal of this research is to derive a vibration model for a vertical axis wind turbineblade. This model accommodates the aects of varying relative ow angle caused by rotatingthe blade in the ow eld, uses a simple aerodynamic model that assumes constant windspeed and constant rotation rate, and neglects the disturbance of wind due to upstream bladeor post. The blade is modeled as elastic Euler-Bernoulli beam under transverse bendingand twist deections. Kinetic and potential energy equations for a rotating blade underdeections are obtained, expressed in terms of assumed modal coordinates and then pluggedinto Lagrangian equations where the non-conservative forces are the lift and drag forces andmoments. An aeroelastic model for lift and drag forces, approximated with third degreepolynomials, on the blade are obtained assuming an airfoil under variable angle of attackand airow magnitudes. A simplied quasi-static airfoil theory is used, in which the lift anddrag coecients are not dependent on the history of the changing angle of attack. Linearterms on the resulting equations of motion will be used to conduct a numerical analysis andsimulation, where numeric specications are modied from the Sandia-17m Darrieus windturbine by Sandia Laboratories.
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