KEY RESULTS FROM A HIGHER HARMONIC CONTROL AEROACOUSTIC ROTOR TEST (HART)

In a major cooperative research program within existing US-German and US-French Memoranda of Understanding (MoU's) a comprehensive experimen tal study was conducted with a 40-percent geometrically and dynamicall y scaled BO-105 main rotor operated in the open-jet anechoic test sect ion of the German-Dutch Wind Tunnel (DNW). The objectives of the progr am were to improve the physical understanding and the mathematical mod elling of the effects of the higher harmonic blade pitch control techn ique on blade-vortex interaction (BVI) impulsive noise and vibration r eduction. A unique set of acoustic, aerodynamic, dynamic response, per formance, and rotor wake data were acquired with a pressure and strain gauge instrumented blade and by application of non-intrusive measurem ent techniques. This paper is focused on the experimental part of this research program, termed Higher-harmonic-control Aeroacoustic Rotor T est CHART) which was jointly performed by researchers from the US-Army Aeroflightdynamics Directorate (AFDD) and NASA Langley, the DNW, and the French and German Aerospace Research Establishments ONERA and DLR. The test procedures applied and key results obtained are presented.