Towards Prediction of Jet Noise Installation Effect using Stochastic Source Modeling

Previously, the prediction of jet mixing noise from hot and cold isolated nozzle configurations has been studied with the means of RPM (Random Particle M esh) method using the Tam & Auriault or rather Tam, Pastouchenko and Viswanathan source model. The acoustical sources are generated as a reproduction of experimentally observed two-point cross-correlation functions using as input the turbulence statistics from RANS data. The sound propagation and extrapolation are performed with the linearized Euler equations in the near-field and with the Ffowcs-Williams & Hawkings method in the far-field. Efficient CAA computations are achieved exploiting the advantage of Fourier series decomposition for isolated axisymmetric and quasi-axisymmetric nozzle geometries. For investigation of installation effects the azimuthal-modal approach is however not applicable due to highly three-dimensional flow interactions, e.g. if a jet engine is mounted below an airfoil. Therefore, in contrast to the isolated nozzle configurations, in this case the resolution of computational domain in all three spatial dimensions is needed. Next to the RPM method, which is solely capable to generate two-dimensional acoustical sources, the FRPM method is available that is able to generate both, 2-D and 3-D sources. First test computations with FRPM method were conducted for a single stream jet, whereas the azimuthal-modal results of RPM were used as reference solution. The installed jet configurations are subsequently studied building on the FRPM computations of the single stream jet.