Hybrid LES/RANS calculation of high speed jet noise

This paper presents near-field and far-field LES results from a hybrid RANS/LES simulation of two high-speed jets at M_∞=0.9 (T _j/T_∞=0.86: Tanna's Set Point 7 (SP7) and T _j/T_∞=2.7: Tanna's Set Point 46 (SP46)).¹⁷ The near-field pressure is analyzed in terms of hydrodynamic wave-packets (Reba et al.¹⁰) to quantify the large scale turbulence noise source. Results indicate that the simulation reasonably captures the spatio-temporal evolution of the large-scale turbulence. However, the LES-predicted turbulence structures appear to be significantly more energetic, with a consistent over-prediction of 10 dB in the near-field pressure. The acoustic far field is computed using a Ffowcs-Williams/Hawkings surface. Acoustic results show good qualitative agreement with the experimental data The predicted far field OASPL directivity pattern compares well with the experiments, despite an over-prediction of 3 dB and 10 dB for SP7 and SP46, respectively.