Uncertainty quantification of low - speed fan noise

Uncertainty quantification (UQ) has been achieved for the first time on the self-noise prediction of a low-subsonic axial fan. Realistic 5% and 4% errors are introduced on the volume flow-rate and the rotational speed, respectively, and a set of 81 ReynoldsAveraged Navier-Stokes (RANS) simulations of the fan mounted on an axisymmetric test plenum has been simulated at Clenshaw-Curtis points. By using the Stochastic Collocation method, extractions from this set of RANS simulations, and reconstructions of the wall-pressure fluctuations with two different models, uncertainties on global performances, wall-pressure distribution, and far-field noise spectra were obtained. The stochastic mean spectra are dominated by the tip strip and compare well with experimental data. Larger uncertainties are seen in the hub and tip regions, where large flow detachment and recirculation appear. Flow rate variations yield larger uncertainties on sound than do rotational speed variations.