Prediction of nonlinear acoustic propagation effects for high-intensity aerospace noise sources in the natural far-field environment

A semi-empirical nonlinear aeroacoustic propagation theory was developed for the prediction of high-intensity flight/launch noise produced by full-scale aerospace operations. The resulting nonlinear aeroacoustic propagation model was verified by analysis of environmental noise propagation measurements on the Concorde, United States Air Force F-4C and F-16A aircraft and the Peacekeeper rocket. Propagation modeling of both aeroacoustic directivity and nonlinear attenuation effects were separately verified to be accurate. Model parameters were derived to document the extent of each physical acoustic effect. The parameters of nonlinear acoustic propagation were empirically demonstrated to be linearly related through analysis of multiple sources. These results verified the formulation of a Simplified Nonlinear Aeroacoustic Propagation (SNAP) model. Such verification supports the potential for application of SNAP to broadband aeroacoustic noise source propagation calculations.