1 Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Department of Wind Energy, Technical University of Denmark3 unknown
This report summarizes the findings of the EFP project WAsP Engineering Version 1.0 DK - Vindforhold for vindmølledesign. WAsP Engineering is a series of experimental and theoretical activities concerning properties of the winds in moderately complexterrain with relevance for loads on wind turbines and other large structures. These properties include extreme winds, wind shear and turbulence. Most of the models have been integrated in a windows program prototype, also called WAsP Engineering. Thebasic mean flow model LINCOM has been changed in several respects to accommodate the demands from load calculations. The most important change is the inclusion of a complex model for the roughness length on water bodies. This is particularly important forthe estimation of extreme winds in the vicinity of sea shores. A second addition is the calculation of spatial derivatives of the mean flow to be used for the modeling of turbulence. The turbulence structure on hills is modeled by perturbing the flat,homogeneous terrain turbulence using Rapid Distortion Theory. A simple model for the adjustment of turbulence to roughness changes is also applied. Second order turbulence statistics such as turbulence intensities, spectra and cross-spectra can beestimated at user-chosen positions in the terrain. A program for simulation of turbulence with the calculated statistics has been developed. However, it has not yet been integrated into the windows interface. Climatological series of wind speed have beenanalyzed to establish the extreme wind climate over Denmark. The extreme wind climate contains directional information and is used for estimating the extreme winds at an arbitrary position in complex terrain. A net of high precision pressure sensorscovering Denmark has been established in order to obtain a climatology of the geostrophic wind. A tentative conclusion from only one year of data is that, statistically, the geostrophic wind decreases when going from west toward east.
Vindenergi og atmosfæriske processer; Risø-R-1179; Risø-R-1179(EN)