Poul la Cour Wind Tunnel at DTU Risø Campus. It is expected to be finished in the beginning of 2018
The Poul la Cour wind tunnel is among the biggest university-owned wind tunnels in the world, and the combination of test possibilities makes the wind tunnel one of a kind, not just nationally but globally. This is due to the size of the wind tunnel and high flow speed as well as the possibility to combine measurements of aerodynamics and noise.
It is, for instance, possible to expose a part of a turbine blade to wind speeds up to 105 meters a second, or 378 kilometres pr. hour, corresponding to three times hurricane strength. The wind is created by a gigantic fan with a diameter of 4,7 meters. Furthermore, the test section is enclosed in a soundproof room to avoid reflections and absorb noise.
Due to the size of the test section, it is possible to not only test parts of turbine blades but also other products, e.g. downscaled models of houses, vehicles and entire wind turbines.
The wind tunnel model, which can be e.g. a wing section, is mounted in the test section, and while it is exposed to the artificial wind from the fan the pressure is measured both on the wing section and on the walls of the test section to determine the forces that the model is exposed to by the air. The noise is measured by microphones placed outside the flow in a room that is surrounding the test section.
The wind tunnel is designed so that the flow in the test section is uniform in the entire cross-section with low turbulence intensity. To save energy and to control the temperature, the flow is re-circulated so that it will pass through four corners mounted with guide vanes which helps the flow to bend. Also, the cross-sectional area is increased all the way from the test section to the settling chamber, partly to save energy and partly to reduce the turbulence. In the settling chamber, there are screens which rectify the flow and create low turbulence. A contraction makes sure to accelerate the flow to maximum flow speed in the test section. To create an accurate picture of the noise from the model in the test section, the noise from the fan and other components is minimized.