2D Laser Velocimetry Near Helicopter Blades in DNW (NLR)

Tests achieved at DNW (windtunnel of NLR) on an helicopter in forward flight conditions had two main purposes: on the one hand to record the components of the velocity vector in a 2D vertical frame around the blade, and on the other hand to simultaneously measure the position of the 2 m long blade which is rotating at a speed of 1050 rpm. Two series of measurements have been performed: the first one in a closed test section (8 m x 10 m) with a working distance of 2.7 m, the second one in an open test section for which this working distance was increased up to 5 m. The optical and mechanical set-up, the synchronization of the measurements and the blade attitude measurement technique are described; the: most typical results are presented.