Aeroelastic analysis of composite wings and wind turbine blades including geometrical nonlinearity and compressibilty

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2018
Farsadi, Touraj
Aeroelastic behaviour of composite wings and wind turbine blades in the incompressible and compressible flow regimes is investigated utilizing a geometrically nonlinear Thin Wall Beam (TWB) theory incorporating non uniform geometric features such as sweep, taper, pretwist, warping inhibition and transverse shear strain. The structural equations of motion are obtained in the most general form based on the kinematic relations governing thin walled beams, including the nonlinear strain displacement relations, and utilizing the principles of analytical dynamics. Unsteady aerodynamic loads in the incompressible and compressible flow regime are expressed using indicial functions in the time-domain. The aeroelastic system of equations is augmented by the differential equations governing the aerodynamics lag states to come up with the final coupled fluid-structure equations of motion. Time response of the nonlinear aeroelastic system is obtained via the Runge-Kutta direct integration algorithm. The effect of the compressibility on the flutter characteristics of aeroelastically tailored bend-twist coupled (BTC) composite blades designed for the MW sized wind turbine is investigated. Flutter analyses are performed for the baseline blade and the BTC blades designed for the MW sized wind turbine. Beam model of the blade is developed by making analogy with the structural model of the prewisted rotating TWB and utilizing the Variational Asymptotic Beam Section (VABS) method for the calculation of sectional properties of the blades designed. To investigate the effect of compressibility on the flutter characteristics of the wind turbine blades, aeroelastic analyses are performed in frequency and time domain utilizing both incompressible and compressible unsteady aerodynamics via indicial function approach.

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Citation Formats
T. Farsadi, “Aeroelastic analysis of composite wings and wind turbine blades including geometrical nonlinearity and compressibilty,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.