Three Component Laser-Doppler-Velocimeter Development for Large Wind Tunnel

Abstract

Within the scope of a co-operative programme between DLR and US Air Force and the DLr programme co-rot a three component laser- Doppler-velocimeter together with a position monitoring system has to be developed in order to determine the unsteady flow field around a rotating helicopter rotor blade. Most of these measurements have to be performed in the DNW (Deutsch-Niederlaendischer Windkanal.The Netherlands), a large wind tunnel with an open test section of 6m-8m. Experiences from previous tests in the DNW on the same helicopter rotor blade with different LDV set-ups were gained and finally led to a 3 component LDV with a working distance of 5m and a 350 mmaperture receiving optics. By the new set-up it was possible to obtain high quality data although the total laser power does not exceed 3 Watts.