| A new noise prediction code has been developed for the purpose of more accurate prediction of complex three-dimensional jets that are typical of realistic aircraft engine installations. The new code, Jet3D-UNS (Jet3D -- Unsteady Navier Stokes) computes Lighthill's acoustic analogy time accurate with the Partially Averaged Navier-Stokes and Large Eddy Simulation turbulence models. In contrast to the existing version of Jet3D that predicts noise from Reynolds Averaged Navier-Stokes CFD solutions, some of the advantages of the method used in Jet3D-UNS are that it does not use two-point correlations or calibration constants. Computations have been performed on a round dual flow nozzle with a bypass ratio of five with and without a pylon attached. The pylon adds three dimensional flow features to the jet that change the azimuthal and axial distribution of noise sources in the jet. For these two configurations, predictions were compared to experimental data. Results show that the unsteady solutions do not match the experimental data as well as the RANS solutions and the noise predictions are inferior to the original JET3D predictions. Further work will include integrating this code with other CFD software and other turbulence models. |
