Based on the aim of the IRPWind, which is to foster better integration of European research activities in the field of wind energy research with the aim of accelerating the transition towards a lowcarbon economy and maintain and increase European competitiveness, the L4WT project brings together boundary-layer wind tunnel and scaled wind turbine testing expertise from NTNU and SINTEF in Norway and cold climate and icing wind tunnel expertise from VTT in Finland with wind lidar expertise from DTU in Denmark with the aim to gain and share knowledge about the possibilities and limitations with lidar instrumentation in wind tunnels and to foster collaboration for alignment of research activities relevant to wind conditions in cold climate.

The continuous-wave short-range WindScanner developed at DTU has the characteristic that the length of the sampling volume increases quadratically with the measurement distance. At ten meters measurement distance, the sampling volume is only about a decimeter long and therefore relevant for studies of wake dynamics of scaled wind turbines in boundary-layer wind tunnels as demonstrated earlier this year [1].

Even smaller measurement volumes can be achieved by compact lidar telescopes (Lidic) that previously were developed at DTU Wind Energy for use as blade-mounted lidars. They can be focused at ranges down to less than a meter and in such a configuration the sampling volume can be small enough to provide the possibility of observing signals from single droplets, which is explored in the present experiment in a wind tunnel chamber with controllable in-cloud icing conditions operated by the IRPWind partner VTT in Helsinki, Finland.

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The lidar telescope mounted on a collaborative robotic arm in the icing wind tunnel at VTT in Finland together with Andrea Vignaroli and Mikael Sjöholm from the section of Meteorology and Remote Sensing at DTU Wind Energy.

[1]  M. F. van Dooren, M. Kühn, V. PetroviĆ, C. L. Bottasso, F. Campagnolo, M. Sjöholm, N. Angelou, T. Mikkelsen, A. Croce,  and  A. Zasso, “Demonstration of synchronized scanning Lidar measurements of 2D velocity fields in a boundary-layer wind tunnel”, Journal of Physics: Conference Series, volume 753, number 7, 072032, 2016, http://dx.doi.org/10.1088/1742-6596/753/7/072032.