Large scale atmospheric structures in space-time over flat terrain

Background

Characterization and modeling of large-scale atmospheric structures in space and time is an interesting basic research topic. Starting from the inertial range limit in the wind speed power spectra, and moving towards the energy containing region and beyond (where these atmospheric structures are found), the current spectral tensor models have difficulties describing fluctuations in terms of amplitude and scale, since its formulation is developed for rapid distortion and micro-meteorological stationary conditions. At the same time, and from a perspective of wind energy applications, these structures are of particular interest when it comes to describing the dynamics of downstream advection of wind turbine wakes and possible spatial variability in mean wind speed and direction referring to classical averaging time spans in the range between 10 to 30 minutes.

Research elements of this project

  • Characterization of large-scale atmospheric structures in space-time. Based on available 2D full-scale data from a dual WindScanner lidar, this stage aims to investigate scale-dependent variation in two horizontal planes, based on measurements made at 50m and 200m above ground level, via wind field reconstruction and spectral analysis.
  • Extension of the Mann-model of the spectral tensor model to large horizontal-scale, space-time structures of sheared turbulence.
  • Validation of the developed model by benchmarking against the full-scale 2D LiDAR recordings as well as against Large Eddy Simulations (LES) interfaced to a meso-scale model. 
  • Benchmarking of wake meandering simulations results from the extended model against previous approaches. From this study, corrections to the meandering model may emerge.

Outcome

  • A better modeling of the elusive "spectral gap" region of the wind speed spectra. Large-scale wind speed fluctuations above energy containing range will be better represented.
  • The development of a more precise tool to predict the effect that large atmospheric structures have on wind farm operation in terms of power production, turbine loads, and the wake effects that can affect the performance of downstream neighboring wind farms.

Contact

Leonardo Andrès Alcayaga Romàn
PhD student
DTU Wind Energy
+4593 51 35 47