Roland Kube

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 Understandings (MoUs) a comprehensive experimental 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, dynamic, dynamic response, performance, and rotor wake data were acquired with a pressure and strain gauge instrumentedblade 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.

A Higher Harmonic Control Test in the DNW to Reduce Impulsive BVI Noise

A model rotor acoustic test was performed to examine the benefit of higher-harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulsive noise. A 40-percent dynamically scaled, four-bladed model of a BO-105 main rotor was tested in the German-Dutch Wind Tunnel (DNW). Acoustic measurements were made in a large plane underneath the rotor employing a traversing in-flow microphone array in the anechoic environment of the open test section. Noise characteristics and noise directivity patterns as well as vibratory loads were measured and used to demonstrate the changes when different HHC schedules (different modes, amplitudes, phases) were applied. Dramatic changes of the acoustic signatures and the noise radiation directivity with HHC phase variations were found.