Assessment of acoustic quality of differently designed control devices

Abstract

Novel wing designs will incorporate advanced wing-tip devices for a quick wake-vortex break down and an increased wing performance through different devices, e.g. differential flap setting, airbrakes (vented spoilers), large winglets, mini trailing-edge devices and sub-boundary layer vortex generators. Advanced wing configurations will enhance the aircraft's capability to perform noise abatement flight procedures, but may also generate excess aerodynamic noise. To provide first information on spectral noise characteristics of different devices, noise measurements were performed to check-out the devices' aeroacoustic characteristics. This study was performed in DLR's Aeroacoustic Wind Tunnel (AWB) on a 1/10.6 scaled A340 model wing in high lift configuration. All different devices were tested individually by means of an acoustic mirror. The following major results were obtained: (1) As a means to enhance the decay of wake vortices but avoid excess aerodynamic noise generation, DFS (except for the 0°/32° configuration) is superior over different spoiler settings or any of the tested individual wake vortex devices. (2) Noise from mini TEDs gain importance for deflection angles above 60°. (3) Even small spoiler deflections cause significant excess noise generation. (4) SBVGs were found to be essentially uncritical with respect to excess aerodynamic noise generation.