Maintenance of fans
in wind tunnels on site
Approximately every 10 years, the rotors of wind tunnels must undergo a “major maintenance”. This includes, for example, a bearing replacement. The conventional method of removing the fan rotor in wind tunnels is to open the roof of the building and lift out the entire rotor by crane through the resulting opening. After work has been carried out on the fan (usually in an external workshop), it is then brought back in through the same opening – the same procedure as for initial assembly.
S. Bleyer GmbH (Germany) and its partner Wenger Lüftungstechnik GmbH (Austria) have developed and also already implemented a method to overhaul the motors of fans in wind tunnels without opening the duct in the classical way, lifting the fan out through the open roof of the unit, taking the fan to a workshop, overhauling the motor and reinstalling it.
Instead, the nose and tail of the fan are now removed in situ, i.e. in the duct itself, so that access to the motor housing and shaft is open and the bearings can be replaced. The method allows nose of the fan to be moved longitudinally with a lateral stability and accuracy of 0.2 mm.
The load of the removed parts does not have to be carried by the tunnel itself, but the heavy load is passed through the tunnel and finally carried by the foundation of the equipment. The process is much more cost-effective and time-saving than the conventional method and has already proved its worth on a 4.7 m diameter wind tunnel fan at BMW in Munich. The technology and service are now offered worldwide.