Acoustic Prediction of LAGOON Landing Gear: Cavity Noise and Coherent Structures

Abstract

Detached-eddy simulations of the LAGOON landing gear configuration are performed using different unstructured meshes. One mesh is generated based on available experimental and numerical data, and based on this first mesh, a second one is carefully designed to improve the solutions in regions of strong unsteadiness. Results are presented in terms of steady and unsteady hydrodynamic data as well as noise predictions, which are performed using the Ffowcs-Williams and Hawkings formulation. Numerical results show good agreement with experimental data available in the literature. A wavelet transform analysis demonstrates that the sound generation in the cavity is an intermittent process that leads to strongly varying amplitudes of the surface pressure and the far-field noise radiation. A proper orthogonal decomposition is employed to identify coherent energetic structures responsible for the cavity tones. Finally, it is shown how the local flow topology affects the impingement of these coherent structures on the cavity.