Measurements and CFD-based Acoustic Computations of Experimentally Simulated Blade-Vortex Interaction (BVI) Noise

摘要

A single bladed AH-1 helicopter rotor blade has been tested to high tip Mach numbers (M_T = 0.8) in a hovering acoustically treated test chamber in the presence of vertical gust fields that simulate a single event helicopter Blade-Vortex Interaction (BVI). These controlled vertical gust disturbances simulate the acoustic phasing of parallel, oblique, as well as a specially designed curved BVI that causes aerodynamic singularities to occur during the interaction process. Far-field acoustic signatures have been measured using a microphone grid in the near in-plane as well as out-of-plane observer regions. Comparisons with theoretical acoustic calculations using CFD inputs have yielded good results for the out-of-plane measurement locations, generally validating the use of CFD coupled with linear acoustic theory. At near in-plane observer regions comparison with CFD-linear theory calculations showed major discrepancies - indicating that a more in-depth analysis of both the theoretical and experimental approaches is required.