Downstream view of the KRG test section with a model in situ. The wake rake used to determine the total pressure reduction in the model's wake is visible in the background.
The KRG's 130-metre storage tube is visible in the background of this image. The tank for liquid nitrogen and the evaporator system stand in the foreground.
There are various main system components, such as nozzles, test sections, quick valves and control valves, in the hall. The flow medium can be cooled to a temperature of minus 150 degrees Celsius in this research facility.
The Cryogenic Ludwieg Tube Wind Tunnel Göttingen (KRG) and the European Transonic Wind Tunnel (ETW) in Cologne are the only wind tunnels in Europe capable of generating the transonic flow conditions of modern transport aircraft at Reynolds numbers representative of real flight.
Experiments with flight Reynolds numbers
This large-scale research facility of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) combines near-sonic speeds with very high Reynolds numbers to enable the accurate simulation of friction effects in the air flow. By using temperatures as low as minus 150 degrees Celsius and pressures of up to 12.5 bar, Reynolds numbers representative of real flight can be reproduced in the KRG's test section. The turbulence in the incoming flow of the KRG is particularly low due to this wind tunnel's special design.
The cryogenic Ludwieg tube wind tunnel is a pillar of current and future aeronautical research at DLR concerning transport aircraft aerodynamics at high Reynolds numbers and for the development of measurement techniques for cryogenic wind tunnels, such as the ETW. The DLR Institute of Aerodynamics and Flow Technology uses it for experimental research as part of its routine work and for projects funded be third parties, from public funding (LuFo, EU) and direct commissions from industry. The research carried out at the KRG, such as that of the EU's Flightpath 2050 project, contributes to the reduction of air traffic emissions.
The KRG is primarily used to conduct research on drag reduction and flow control on wing profiles for future transport aircraft, which is mainly achieved using laminarisation. For these activities, the precise simulation of flight conditions is becoming increasingly important, and the KRG is the perfect instrument. Due to its large Mach number and Reynolds number operating range, the wind tunnel is also ideal for validating aerodynamic design and prediction methods, which are increasingly used in modern transport aircraft development.
Contact
Volker Speelmann
Head of Research Infrastructures
German Aerospace Center (DLR)
Executive Board department for Innovation, Transfer and Research Infrastructure
Linder Höhe, 51147 Cologne
Dr. rer. nat. Stefan Koch
German Aerospace Center (DLR)
Institute of Aerodynamics and Flow Technology
