The HELINOISE Aeroacoustic Rotor Test in the DNW

In a major cooperative research program between 8 European partners, a geometrically and dynamically scaled and highly instrumented model of the ECD (formerly MBB) BO-105 helicopter main rotor was tested in the open-jet anechoic test section of the German-Dutch Wind Tunnel, DNW, in the Netherlands. A comprehensive set of simultaneous aerodynamic and acoustic pressure data as well as dynamic and performance data were measured for the standard rotor (NACA 23012 mod) with rectangular blade tips. The primary objective of this experimental study was to generate an extensive airload and acoustic data base for code validation, to examine the relation between the blade pressure characteristics and the acoustic radiation, and as a further objective to obtain initial detailed information on blade-tip vortex trajectories and blade positions during blade-vortex interactions. This report describes the instrumented model rotor, the Modular Wind-tunnel Model (MWM) test stand, the aerodynamic and acoustic data acquisition systems, and the scope of the test matrix and of test conduction. Moreover, the measurement techniques used to visualize the interacting vortex flow and to determine blade deflection and incidence at the blade tip are briefly outlined. Selected test results are presented in this report which is accompanied by a number of appendices and enclosures wherein the experimental results are documented in full. The data is expected to improve the understanding of rotor aeroacoustics and to further the validation of various aerodynamic and acoustic codes developed or improved by the partners of this joint European venture.