Task 2 Baseline A340 Main Landing Gear Noise Tests

Abstract

Baseline noise testing within the subject RAIN-Project (RAIN: Reduction of Airframe and Installation Noise) of a A340 full-scale main 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 main 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 main landing gear configurations aimed at the identification of noise sources distribution and ranking. The results from this baseline test programme revealed, that noise from numerous gear components contribute to the total noise signature. As a consequene operational - i.e. locally applied - noise reduction devices can only provide a noise reduction potential of about 3 dB.