Hybrid acoustic predictions

Hybrid acoustic prediction combines the use of unsteady computational fluid dynamics for calculating the properties of acoustic sources with some form of Lighthillʹs acoustic analogy to calculate the resulting far-field noise radiation. This approach avoids some of the difficult issues involved in computing both the acoustic sources and the acoustic propagation in a single computation. However, hybrid acoustic prediction still faces numerous uncertainties associated with the computation of the properties of the acoustic sources, and the coupling of the noise-source computation with the acoustic propagation computation. Several of these uncertainties are discussed, including examples where some of the issues have been successfully resolved.