Baseline A340 Nose Landing Gear Noise Tests

Kurzfassung

Baseline noise testing within the subject RAIN-Project (RAIN: Reduction of Airframe and Installation Noise) of a A340 full-scale nose landing gear in the DNW aimed at determining the dominant noise sources and at providing a reference data set for comparing existing noise predictions and to improve the modelling methodology and a noise reduction study. Noise from the nose landing gear was found to contain high level tones which were determined to originate from flow over cavities in the numerous pins connecting different gear components. The evaluation of broadband noise data yield a noise levels increase with flow speed according to a 6th-power law and frequencies to scale on a Strouhal-number basis. The noise directivity is almost omnidirectional. Testing of different nose landing gear configurations aimed at the identification of noise sources distribution and ranking. The results from this programme revealed, that noise from numerous gear components contribute to the total noise signature. As a consequence operational-i.e. locally applied - noise reduction devices can only provide a noise reduction potential of about 3 dB.