TURBOFAN BROADBAND NOISE PREDICTIONS BASED ON A ZDES CALCULATION OF A FAN-OGV STAGE
Résumé
This paper presents undergoing acoustic analyses of an hybrid RANS/LES calculation performed at ONERA in the framework of an European project TurboNoiseBB. The numerical approach proposed here relies on a Zonal Detached Eddy Simulation strategy that is applied to a fan module equipped with 20 rotor blades and 44 outlet guide vanes and tested in AneCom facility (Wildau, Germany). The ZDES method with detailed numerical setup and aerodynamic flow features are discussed in a companion paper and the present one mainly focuses on acoustic analyses. Post-processed data are used to feed acoustic codes based on Amiet theory and Ffowcs-Williams and Hawkings analogy for which required inputs to assess rotor-stator interaction noise are the turbulence wake information and the unsteady pressure over the vane wall, respectively. The turbulent wake characteristics in terms of energy and spectral content are compared to hot-wire measurements. In particular radial profiles of turbulent velocity components and power spectrum density at selected duct height positions are analyzed, as well as integral and spanwise correlation length scales. Hence, sound power spectra in the bypass predicted by both acoustic codes are presented and compared to the experiment.
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