DNW innovations in wind tunnel testing: new moving belt system for Large Low speed Facility

The German-Dutch Wind Tunnels DNW is one of Europe’s most advanced and specialized organizations for wind tunnel testing. DNW’s 11 wind tunnels include subsonic, transonic and supersonic facilities, and provide experimental aerodynamic simulation capabilities to a global user community at large. DNW provides techniques for aerodynamic, aeroacoustic or aeroelastic simulations and tests of scaled models in a controlled environment. Its experimental simulation techniques capture the essence of the issues to be investigated. The Large Low speed Facility (LLF) in Marknesse (the Netherlands) is an industrial wind tunnel for the low-speed domain. It is a closed circuit, atmospheric, continuous low-speed wind tunnel with one closed wall and one configurable (slotted) wall test section and an open jet. Low speed means testing of aircraft in take-off and landing flight configurations and therefore DNW focusses its investments for the LLF on safety (ground proximity, powered and unpowered) and environmental issues (acoustics) related testing capabilities. Recent DNW-LLF upgrade programs focussed on ground proximity simulation (procurement of a new moving belt system) and reducing of wind tunnel circuit background noise level to improve its capabilities and market attractiveness. The main drive for the latter initiatives is a clear trend in aircraft characteristics, i.e. continuous reduction of aircraft noise levels. Funding support was provided by the Ministry of Economic Affairs (the Netherlands), the German Aerospace Center DLR and the European Commission through EU 7th Framework European Strategic Wind tunnels Improved Research Potential ESWIRP. The paper will further detail the various development steps taken for the new moving belt system and elaborate on the calibration activities conducted.