Background



The Bolund project is a combined measurement and modeling project related to wind conditions in complex terrain. An isolated steep hill, Bolund, at Roskilde Fjord was equipped with ten measurement masts with conventional meteorological instruments and remote sensing Lidars at several positions for obtaining detailed information of mean wind, wind shear, turbulence intensities etc. The data was gathered in a database for validating advanced  flow models.

Background
Numerous numerical codes for the calculation of flow and turbulence over complex terrain exist; from the fast-running linearized Jackson-Hunt type models to many sophisticated non-linear models: RANS, DES, LES, etc. Common for all these are that they use the famous Askervein experiment for verification. The Askervein hill is nearly Gaussian with not too steep slopes, which is not too challenging for todays numerical codes.

The ambitious goal of the Bolund experiment is to measure the flow in great detail over a very steep terrain and provide for the community a comprehensive database of mean flow and turbulence statistics to be compared with any atmospheric flow model available.

Purpose
The purpose of the Bolund project is to develop reliable methods for determining local wind conditions in complex terrains based on remote sensing techniques (Lidar) as well as conventional meteorological instruments in combination with advanced flow computations.

Time series of wind speeds and turbulence will be collected and analyzed at ten measurement masts equipped with sonics and cup anemometers at several heights together with data from Lidars at several positions. The measurement campaign will take place from December 2007 to end of February 2008. These measurement data will form a basis for a detailed verification of advanced flow models based on the Navier-Stokes methodology.

The project includes four major tasks:

  • Identification of characteristic flow conditions over complex terrain for reliable estimation of power production and wind turbine loads. 
  • Development of remote sensing techniques for measuring flow conditions in complex terrain including wind shear, turbulence intensities etc., at potential wind turbine positions. 
  • Application and further validation of advanced Computational Fluid Dynamics (CFD) models for flow over complex terrain. 
  • A publicly available comprehensive database consisting of experimental data will be built and used for evaluation of currently available flow models and methodologies for turbine siting in complex terrain regarding both wind resources and loads.

 

 

Page updated  by   29.08.2011


Andreas Bechmann
Senior Scientist
Wind Energy (VEA)
Dir tel+45 46775967