Airframe Noise–Landing Gear Noise

Abstract

AbstractNoise originating from flow around aircraft landing gears is one of the major components of aircraft noise in the approach phase. Owing to the complex structure of landing gears, they represent a cluster of aerodynamic noise sources that are difficult to deal with for the purpose of noise reduction. Moreover, a variety of safety and operational constraints must be considered. Landing gear noise intensity increases proportionally to the 6th power of flow velocity while the sound frequencies increase linearly with the velocity. Through wind tunnel tests on full‐scale gears, typical noise characteristics (spectrum and directivity) and the noisiest gear components can be identified. On the basis of this knowledge, both noise prediction models and add‐on noise reduction fairings can be developed. Such fairings, to protect complex gear structures from high‐speed inflow, provide the only limited noise reduction potential. Much higher noise benefits can be achieved for new landing gears of future aircraft, when aeroacoustic constraints are introduced as an additional design criterion, thus enabling a low‐noise design of both the overall gear architecture and of individual gear components. On top of that, both passive and active flow control means can be applied locally to gear components for further noise reduction.