Key Results from a Higher Harmonic Control Aeroacoustic Rotor Test (HART) in the German-Dutch Wind Tunnel

Abstract

In a major cooperative research program within existing US-German and US-French Memoranda of Understanding (MoU's), a comprehensive study was conducted with a 40-percent geometrically and dynamically scaled BO-105 main rotor operated in the open-jet anechoic test section of the German-Dutch Wind Tunnel (DNW). The objectives of the program were to improve the physical understanding and the mathematical modelling of the effects of the higher harmonic blade pitch control technique on blade-vortex interaction (BVI) impulsive noise and vibration reduction. A unique set of acoustic, aerodynamic,dynamic response, performance, and rotor wake data were acquired witha pressure and strain gauge instrumented blade and by application of non-intrusive measurement techniques. This paper is focused on the experimental part of this research program, termed Higher-harmonic- control Aeroacoustic Rotor Test (HART) which was jointly performed by researchers from the US Army Aeroflightdynamics Directorate (AFDD) and NASA Langley, the DNW, and the French and German Aeropace Research Establishments ONERA and DLR. The applied test procedures and obtained key results are presented.