Aircraft noise reduction technologies: A bibliographic review

A bibliographical review of the main technologies employed for the mitigation of aircraft noise is presented. According to a component-based approach, analytical and semi-empirical models of the aeroacoustic mechanisms involved in the noise generation from airframe and engine components are presented as a key element of the noise reduction technology. These models, developed in the past to investigate the influence of some design parameters on the overall acoustic levels, are nowadays powerful design tools when employed in a multi-disciplinary optimization framework. In this spirit, the recent achievements in the numerical prediction of complex aeroacoustic phenomena through CFD/CAA techniques, not addressed in this work, provide a complementary approach to experiments to improve the accuracy of the available analytical and semi-empirical models. The bibliographical style of the paper is guaranteed by a qualitative description of the underlying physical mechanisms and their mathematical idealization. The reader is therefore remanded to the cited works for a deeper analysis.