Computation of Rotor Noise Generation in Turbulent Flow Using Large-eddy Simulation
نویسنده
چکیده
by Junye Wang A computational study is carried out to investigate the noise generated by a ten-bladed rotor ingesting low-Mach-number turbulent flow. Two types of turbulent inflows are considered: homogeneous and isotropic turbulence mimicking gridgenerated turbulence in a previous experiment and a turbulent cylinder wake. A hybrid computational approach combining LES with Lighthill’s aeroacoustic theory is employed to predict the aeroacoustic response of the rotor. LES based on incompressible flow equations provides the unsteady loading on the rotor blades, and the Ffowcs Williams-Hawkings extension to the Lighthill theory is used to calculate the radiated acoustic field. The rotor acoustic response to grid-generated turbulence is calculated at two advance ratios and validated against the experimental data of Wojno et al. (AIAA J., 40(1), 2002) The noise spectra are broadband with small peaks at the blade passing frequency and its harmonics. The turbulence ingestion noise is much stronger than the rotor self noise. It is found that decreasing the rotor advance ratio at fixed freestream velocity increases the sound pressure level. Turbulence distortions by the rotor are insignificant, and blade-to-blade correlations of the acoustic dipole sources are weak. The noise of rotor ingesting a turbulent cylinder wake is studied at several advance
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