Comparison of Zephir and Windcube measurements in the same complex flowfield

Stickland, Matthew and Scanlon, Thomas and Fabre, Sylvie (2011) Comparison of Zephir and Windcube measurements in the same complex flowfield. In: EWEA Offshore 2011: Moving Ahead of the Energy Curve, 2011-11-29 - 2011-12-01.

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    Abstract

    Offshore wind is the major growth area in the wind industry sector today. However, there remains a key, fundamental missing element - a thorough understanding of the offshore wind climatology and likely wind resource. In 2008 the EU FP7 funded project NORSEWInD was created with a remit to deliver offshore wind speed data at a nominal project hub height acquired in offshore locations in the North, Baltic and Irish seas. Part of the NORSEWInD project is the use of LiDAR remote sensing (RS) systems mounted on offshore platforms to measure wind velocity profiles. The data acquired from the offshore RS measurements are fed into a large wind speed dataset suitable for use by the wind industry. One significant problem identified was the effect of platform interference effects on the RS data. Another significant effect on the quality of the data produced was the method by which the wind speed and direction was acquired as the method by which LiDARs measure the wind vector is significantly different from a point measurement. Whilst this will have no effect in a homogeneous flow field if there is significant flow distortion, which might be found in close proximity to a large structure or in complex terrain, then the effect of this spatially averaged measurement might cause a significant deviation from a point measurement. This paper reports on the modelling of two different types of LiDAR, the Natural Power ZephIR and the Leosphere Windcube, in a computational fluid dynamics simulation of the flow around a large offshore structure. The paper discusses the difference in the measured wind vector when compared to a point measurement at the measurement height.