The German National Program on Airframe Noise Reduction - Pertinent Wind Tunnel Experiments on Source Identification and Airframe Noise Reduction of Wing High Lift Configurations

Kurzfassung

The development of low-noise high-bypass-ratio engines to power modern large commercial aircraft caused airframe noise levels for the aircraft in its approach configuration to be compatible to those of the engines. As a consequence,noise from aircraft components deployed during the final approach leg, such as landing gears and high-lift devices (HLD) on wings will become ever more important. In view of European aviation industry to design and build a very large commercial aeroplane, a predominantly experimental study on wing configurations with deployed high-lift devices was initiated to identify and rank order sources and describe relevant airframe noise mechanisms, develop and assess airframe noise control measures and develop or improve airframe noise prediction methods. One essential outcome of this German national research programme will be a number of proposals for low airframe-noise configurations specified for different airframe components (such as slats, flaps, wing-tips, etc.). At the same time a better understanding of noise mechanisms is expected, leading to improved prediction capabilities. In this paper results of the scale-model experiments in the Aeroacoustic Wind Tunnel Braunschweig are presented as well as initial results from noise testing on a 1:7.5 scaled full aircraft in the DNW.