Large-eddy simulations of chevron jet flows with noise predictions

Hybrid large-eddy type simulations for chevron nozzle jet flows are performed at Mach 0.9 and Re = 1.03 x 10(6). Without using any subgrid scale model (SGS), the numerical approach applied in the present study is essentially implicit large-eddy simulation (ILES). However, a Reynolds-averaged Navier-Stokes (RANS) solution is patched into the near wall region. This makes the overall solution strategy hybrid RANS-ILES. The disparate turbulence length scales, implied by these different modeling approaches, are matched using a Hamilton-Jacobi equation. The complex geometry features of the chevron nozzles are fully meshed. With numerical fidelity in mind, high quality, hexahedral multi-block meshes of 12.5 x 10(6) cells are used. Despite the modest meshes, the novel RANS-ILES approach shows encouraging performance. Computed mean and second-order fluctuating quantities of the turbulent near field compare favorably with measurements. The radiated far-field sound is predicted using the Ffowcs Williams and Hawkings (FW-H) surface integral method. Encouraging agreement of the predicted far-field sound directivity and spectra with measurements is obtained. (C) 2009 Elsevier Inc. All rights reserved.