Detailed induction zone wind field measurements over sloping terrain

Description

We present high-resolution 2D wind field measurements scanned upwind in the induction zone of an 850 kW and 52 m rotor diameter (D) DTU test wind turbine (Vestas V52).
Two high-resolution synchronised lidars [1] (6” short-range WindScanners) scanned the inflow in a 2D vertical plane between the turbine rotor and an upwind met-mast located at +2.2D. A DTU SpinnerLidar installed on top of the turbine nacelle scanned the wind field crosswind in the rotor plane at +1D.
We compare the lidar-scanned wind field measurements with vertical profile measurements at five heights in the met-mast equipped with cup anemometers and sonic anemometers, cf. Fig. 1.
We have investigated two cases obtained during periods when the mean wind direction aligned favourably within a few degrees with the met-tower turbine connection line. The first, characterised by strong winds, encountered during June 4., 2018, of average wind speed 17 m/s and another, encountered on December 10. 2018, with average wind speed about 10 m/s (Fig. 1) will be presented.
During Westerly winds (291 degrees) the turbine, installed 9 m above sea level, experiences heterogeneous inflow through the met-mast located at +2.2D and installed 7 m above sea level. Further upwind, a relative steep escarpment of approximately 6 m height lead down towards the coastline 225 m upwind that also influenced the flow field. Fig. 1 shows the terrain (bottom), the two WindScanners (black squares), the met-masts five measurement heights (black dots), and the SpinnerLidars scanning range +1D in front of the turbine. In addition, the reduction in wind speed in front of the V52 nacelle is apparent.
The vertically scanned 2D wind field between the met-mast and the turbine show significant influence incurred by both turbine induction zone and terrain effects: caused by the escarpment, an increased wind speed extends from the ground and up to approximately 40 m height. In front of the turbine, the vertical wind components diverges due to induction around the rotor. Stagnation in front of the turbine is observed already in the met-towers vertical profile. At +1D, the SpinnerLidar simultaneous acquired line-of-sight measurements on a 30 degrees cones spherical surface. Data was used to calculate mean wind fields of all three wind components using the fast CFD code LINCOM[2]. In addition, the SpinnerLidar reconstructed 3D wind fields also show influence of induction-reduced inflow and flow divergence around the rotor.

Period	17 Jun 2019 → 21 Jun 2019
Event title	Wind Energy Science Conference 2019: Wind Energy Science Conference 2019
Event type	Conference
Location	Cork, IrelandShow on map
Degree of Recognition	International