Nonlinear aeroelasticity of H-type vertical axis wind turbine blade: Fid-Bau Portal

Nonlinear aeroelasticity of H-type vertical axis wind turbine blade

Badiei, Davood / Sadr, Mohammad H. / Shams, Shahrokh

Abstract This article presents the nonlinear aeroelastic analysis of the H-type Darrieus wind turbine blade. The blade structural flexibility subjected to unsteady aerodynamic loading in Darrieus motion is the main characteristic of the blade. Large displacements and rotations of the blade at high angle of attacks are considered to study fully nonlinear aeroelastic analysis of the blade under dynamic stall conditions. The third-order Taylor expansion of nonlinear Euler-Bernoulli beam equations was coupled with a new semi-empirical dynamic stall model for aerodynamic loading to form governing nonlinear aeroelastic equations of the blade. The introduced dynamic stall model minimizes the dependent parameters on experimental data of the blade section and presents nonlinear algebraic equations to simulate aerodynamic lift and pitching moment coefficients hysteresis in dynamic conditions. The set of the nonlinear aeroelastic equations of the blade is solved using the Galerkin method, and the modeling is validated by the published results in the literature. Moreover, the nonlinear aeroelastic behavior of the blade, such as nonlinear instability speeds and limit cycle oscillations (LCOs), are investigated. The results show that the difference between the relative wind speed and the LCOs speed of the blade tip is minimized around 60 ͦ and 300 ͦ azimuth angles.

Highlights • Dynamic stall makes the blade prone to chaotic behavior in the second and third quarters of the turbine revolution. • Minimum difference between relative wind speed and nonlinear instability speed occurs at 60 and 300-degree azimuth angles. • Blade tip bending and twist deflections are maximized at about 300-degree azimuth angle.