In a cooperative research program between eight European partners, a 40 % 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. The primary objectives of this experimental study were 1) to improve the physical understanding of the impulsive rotor noise sources by correlating blade pressure and acoustic characteristics and 2) to provide an extensive airload and acoustic database for code validation purposes. Consequently, a comprehensive set of simultaneous acoustic and aerodynamic blade surfaces pressure data as well as blade dynamic and performance data were measured for the standard rotor with rectangular blade tips. In addition, initial quantitive information of the blade-vortex miss distance during blade-vortex interaction (BVI) was obtained. This paper describes the model and summarizes the aeroacoustic key results. The blade pressure characteristics are examined to identify regions of impulsive loading due to BVI at descent condition and of supersonic flow at high tip speed. Comparisons with the corresponding characteristics of the radiated sound pressure fields provide improved insight into the physics of the impulsive noise mechanisms. For descent flight, the strong change of BVI noise directivity and level with descent condition is illustrated, and the importance of the blade-vortex miss distance shown.
Experimental results of the European HELINOISE aeroacoustic rotor test
Experimentelle Resultate des europäischen HELINOISE-Aeroakustik-Rotortestprogrammes
Journal of the American Helicopter Society ; 40 , 2 ; 3-14
1995
12 Seiten, 17 Bilder, 24 Quellen
Aufsatz (Zeitschrift)
Englisch
Hubschrauber , Rotor (Drehflügel) , Aerodynamik , Wirbelströmung , Schallmessung , dynamische Belastung , experimentelle Untersuchung , Versuchsmodell , Instrumentierung , Windkanal , Schallquelle , Druckbeanspruchung , Rechnerprogramm , supersonische Geschwindigkeit , Schalldruck , Validierung , Aeroakustik
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