Aeroacoustic Assessment of Low-Observable UCAV Configurations

Abstract

First, results of experimental and numerical investigations on generic engine noise shielding by the SACCON UCAV configuration are presented. The results suggest that propulsion system intake noise is much less attenuated compared to exhaust noise. This is a consequence of the position of the intake on the symmetry plane of the UCAV as well as to the relatively large radius of curvature of the aircraft wings leading edge. This result emphasizes the potential necessity to achieve an acoustically optimized integration of both intake and exhaust altogether to maximize acoustic attenuation. The use of a generic, monopole-like, sound source in the experimental and numerical assessment of SACCON (Stability And Control CONfiguration) leaves many open questions with respect to the acoustic signature of a real UCAV configuration. For real highly-integrated propulsion systems, noise radiation from the intake and exhaust is critical to the acoustic detection of an aircraft, especially to low-observable configurations. Aiming at an assessment of the noise signature of a realistic UCAV configuration at an early design stage, experimental and numerical methodologies are presented which are able to account for mean flow and airframe interaction effects on noise generation and propagation. DLR-F24 MULDICON UCAV (MULti-Disciplinary CONfiguration) test bed is introduced, along with numerical simulations results providing first insights into the aeroacoustics of a realistic agile UCAV configuration.