Simulating the dynamics of wind turbine blades: part II, model validation and uncertainty quantification

Verification and Validation (V&V) activities play an indispensible role in the modeling and simulation of wind turbine blades. The purpose of this paper is to spotlight the process, through simple validation activities, as it is applied to a wind turbine blade. The ANSYS Finite Element (FE) software is used to develop a three-dimensional solid model of the CX-100 wind turbine blade designed at the Sandia National Laboratories, and predict its low-order vibration dynamics. While the geometry of the CX-100 blade is represented accurately, the model assumes smeared cross-sections with isotropic material properties. The goal is to demonstrate how V&V activities contribute to the development of a simplified, yet, validated, structural model of the blade. Code and solution verification steps are discussed in Part I of this effort. Here, designs-of-computer-experiments are used to explore the effect of uncertainty in model parameters on the prediction of modal response. Gaussian process models are developed to reduce the uncertainty in FE model parameters to a probability distribution that, when sampled, produces prediction uncertainty bounds consistent with the experimental variability. After studying the free-free vibration response, a similar procedure is applied to the fixed-free measurements to develop an idealized representation of the boundary condition. A test-analysis correlation of the mode shapes is performed to demonstrate the ability of the FE model to properly predict the bending of the blade. This work is Part II of a two-part publication that highlights the V&V steps required to develop a robust wind turbine blade model.