Noise Prediction of the LAGOON Landing Gear Using Detached Eddy Simulation and Acoustic Analogy

摘要

This paper presents detached eddy simulations, DES, of the LAGOON landing gear configuration performed using different unstructured meshes. We employ the BCFD code for the DES calculations and results are compared to experimental measurements available in the literature. An implicit dual-time stepping method is employed together with an optimized second-order backward-differencing scheme. For the spatial discretization, a second order accurate HLLE scheme is employed together with a bounded central differencing approach to reduce numerical dissipation of the flux reconstruction. Results are presented in terms of steady and unsteady hydrodynamic data as well as noise predictions, which are performed using the Ffowcs Williams & Hawkings formulation. Overall, numerical results show a good agreement with experimental data. The paper also includes an assessment of the proper orthogonal decomposition, POD, of the unsteady flow field in order to identify coherent energetic structures responsible for the cavity tonal noise mechanism at specific frequencies. Here, the POD technique employs a filter function to the correlation matrix which allows the analysis of POD spatial eigenmodes at specific frequencies. At 1.5 kHz, coherent structures which are responsible for tonal noise generation are observed along the cavity. Results from a wavelet decomposition demonstrate that the sound generation in the cavity is an intermittent process.