Experimental and numerical investigation of aeroacoustic sources in a strut-braced wing configuration

Airframe noise is expected to become increasingly relevant for future low-noise aircraft concepts, motivating the need for aeroacoustics investigations of unconventional configurations such as strut-braced wings (SBWs). This work presents a combined experimental and numerical investigation of the aerodynamic and aeroacoustic fields of a realistic SBW configuration. High-fidelity lattice-Boltzmann very-large-eddy simulations are employed, complemented by wind-tunnel experiments performed in the acoustically treated Low-Turbulence Tunnel (LTT) at TU Delft. The numerical framework accurately reproduces the mean aerodynamic field, wake topology, junction-flow structures, wall-pressure fluctuations, and far-field acoustic trends. The acoustics analysis for an observer beneath the wing reveals the coexistence of multiple aeroacoustic source mechanisms associated with the wing trailing edge, strut trailing edge, and junction-flow structures. For this observer direction, source-decomposition analysis shows that trailing-edge mechanisms dominate at low frequencies, with the strut- and wing-trailing-edge contributions exceeding the junction contribution by approximately 10 and 7 dB, respectively, while the dominant source progressively shifts towards the junction/corner region for Stc ≳ 93. The results provide new physical insight into the relative importance of the different aeroacoustic sources present in SBW configurations and their evolution across frequency, supporting the development of future reduced-order and high-fidelity prediction methodologies for low-noise unconventional aircraft concepts.