Finite element analysis and modal testing of a rotating wind turbine

Abstract

A finite element procedure, which includes geometric stiffening, and centrifugal and Coriolis terms resulting from the use of a rotating coordinate system, * This work was performed at Sandia National Laboratories and was supported by the U. S. Department of Energy under contract number DE-AC04-76DPO0789.

Full-scale modal wind turbine tests: comparing shaker excitation with wind excitation

“…The optimal design of a turbine is dependent on reducing vibrations, which can be done by accurately identifying turbine's natural frequencies and mode shapes [2]. By determining the modes of the wind turbine, it can be ensured that the turbine's operational conditions preclude resonant frequencies, thereby minimizing dynamic loads and lengthening the life of the turbine [2] [3]. In order to develop accurate structural models, extensive experimental testing must be done to refine and validate computer simulations.…”

“…Rotational testing has been conducted since the 1980s. Carne et al [3][6] [12][13] focused on vertical-axis wind turbines (VAWTs), which do not deal with the changes in gravitational forces acting on the rotating structure or the bending moments acting out of the plane of rotationchallenges that rotating horizontal axis turbines face. Horizontal-axis wind turbines (HAWTs) have been tested with a variety of excitation methods [9].…”

“…Standstill modes are useful for validating and refining models, however there is no inclusion of the rotational effects that dominate modes [9]. Modal characteristics vary between a parked and rotating turbine, so including rotational effects is important for computing modal parameters [3] [6]. Rotational testing has been conducted since the 1980s.…”

The inception of OMA in the development of modal testing technology for wind turbines

“…(See, for example, [2 and 3].) A new capability was developed in 1982, [3], which proposed to include all appropriate terms, but required experimental validation so that it could be applied to new and existing turbine designs. This new capability included the standard effects of tension stiffening, as well as the centrifugal and the Coriolis terms.…”

Salinas : theory manual.

“…In the first approach, a rotating coordinate system is constructed that rotates with the structure. [51][52][53] Then, relative deformations about that rotating coordinate system are sought. In the second approach, an Eulerian (ALE) formulation is used, in which the structure rotates through an Eulerian mesh, and then Lagrangian deformations are considered about the Eulerian configuration.…”