Propeller Testing in the Cryogenic Wind Tunnel Cologne DNW-KKK

To increase performance and meet environmental constraints for the propeller aircraft, the Cryogenic Wind Tunnel Cologne (DNW-KKK) has developed and implemented the appropriate technology. The most significant aspects relate to the cryogenic electric motor drive, force measurement and flow field investigation with stereo PIV. The model propeller is mounted at the 3-D support of DNW-KKK. It is driven by a cryogenic electric motor. The thrust and the torque are measured by a fixed cryogenic six-component balance. The influence of cooling with liquid nitrogen on the force measurement is negligible. The electric motor is a permanent magnet synchronous motor cooled by liquid nitrogen. Its total loss is small and the power density can be high. The dimension is 070x200 mm. The maximum power is 12.5 kW and the maximum rotation speed is 8300 RPM. Test results showed that the propeller performance can be measured accurately at DNW-KKK. A stereo-PIV setup was used to investigate the flow field around the propeller. Two cameras aligned at an angle of 60° to each other are used to record the images. The laser light sheet is directed to the propeller through a set of optics which is mounted closely to the tunnel side wall.