On characteristics of stable boundary layer flow fields and their influence on wind turbine loads

dc.contributor.advisorManuel, Lanceen
dc.contributor.committeeMemberBasu, Sukantaen
dc.creatorPark, Jinkyooen
dc.date.accessioned2011-09-30T17:06:17Zen
dc.date.available2011-09-30T17:06:17Zen
dc.date.issued2011-08en
dc.date.submittedAugust 2011en
dc.date.updated2011-09-30T17:06:47Zen
dc.descriptiontexten
dc.description.abstractFourier-based stochastic simulation of wind fields commonly used in wind turbine loads computations is unable to account for contrasting states of atmospheric stability. Flow fields in the stable boundary layer (SBL), for instance, have characteristics such as enhanced wind shear and veering wind direction profiles; the influence of such characteristics on utility-scale wind turbine loads has not been studied. To investigate these influences, we use large-eddy simulation (LES) to generate inflow wind fields and to estimate load statistics for a 5-MW wind turbine model. In the first part of this thesis, we describe a procedure employing LES to generate SBL wind fields for wind turbine load computations. In addition, we study how large-scale atmospheric conditions affect the characteristics of wind fields and turbine loads. Next, in the second part, we study the contrasting characteristics of LES-SBL and stochastic NBL flow fields and their influences on wind turbine load statistics by isolating effects of the mean wind (shear) profile and of variation in wind direction and turbulence levels over the rotor sept area. Among large-scale atmospheric conditions, the geostrophic wind speed and surface cooling rate have the greatest influence on flow field characteristics and, thus, on wind turbine loads. Higher geostrophic winds lead to increased mean and standard deviation values of the longitudinal wind speed at hub height. Increased surface cooling rates lead to steeper shear profiles and appear to also increase fatigue damage associated with out-of-plane blade root moments. In summary, our studies suggest that LES may be effectively used to model wind fields in the SBL, to study characteristics of turbine-scale wind fields, and to assess turbine loads for conditions that are not typically examined in design standards.en
dc.description.departmentCivil, Architectural, and Environmental Engineeringen
dc.format.mimetypeapplication/pdfen
dc.identifier.slug2152/ETD-UT-2011-08-4368en
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2011-08-4368en
dc.language.isoengen
dc.subjectLarge-eddy simulationen
dc.subjectStable boundary layeren
dc.subjectNBLen
dc.subjectTurbulenceen
dc.subjectLoad computationsen
dc.subjectInflow wind fieldsen
dc.titleOn characteristics of stable boundary layer flow fields and their influence on wind turbine loadsen
dc.type.genrethesisen
thesis.degree.departmentCivil, Architectural, and Environmental Engineeringen
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorUniversity of Texas at Austinen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Science in Engineeringen

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