10 Years Research and Application in the Climate Wind Tunnel

Wind tunnel testing as an experimental method including a device that creates an artificial airflow to which models and objects are exposed under controlled and repeatable conditions, has been around since the late 19th century. One of the main purposes of these tests still is the study of aerodynamic loading on objects and their response behavior spanning over numerous applications in Civil, Mechanical and Aeronautical Engineering. Even though each wind tunnel has its specific characteristic and capabilities do many share a similar range of applications. However, some are purposely designed to focus on specific phenomena or to create particular boundary conditions, which are not included in standard setups. One example is the 2018 inaugurated Poul La Cour wind tunnel at DTU Risø Campus, one of the world largest university-owned wind tunnels, which as a national specialized test facility is dedicated to study the noise emission from wind turbine blades. For this purpose, the airline including the fan unit was particularly designed to absorb and to minimize the generation of sound at high airspeed. It also allows for more standard testing such as aerodynamic drag and lift on wing section, but its acoustic performance and test array deviates significantly from most other wind tunnel facilities within the wind energy sector and constitutes is unique value for research and development. Another example is the Climatic Wind Tunnel (CWT) at FORCE Technology, which was particularly designed to replicate conditions of atmospheric incloud icing, freezing rain and snow accumulation on bridge cable sections. Designed and constructed from 2008 to 2009, the CWT was put into service at the beginning of 2010. After a run-in phase, the tunnel was extensively used to study ice accretion on bridge cables and the scope quickly expanded and includes today as well atmospheric icing of wind turbine wings. Throughout the past 10 years, the understanding of the thermodynamic processes and their sensitivity to atmospheric boundary conditions played a central role and the experimental setup and wind tunnel instrumentation was constantly improved, extended and refined. Covering a 10 year span of research and development, the paper can only give a selected overview of the conducted work striving to do the collective effort some justice. The selected topics reflect the variety of research activities in the CWT but they are not presented at scale to the actual amount of work done on the individual topics.