Chapter 6 - Sound generation, propagation, and radiation in/from an aeroengine nacelle

Abstract

This chapter introduces fundamental knowledge regarding the methods of determining the sound attenuation, source-acoustic treatment interaction, and sound radiation from the inlet and exhaust of an aeroengine. Especially, emphasis will be put on how to use a kind of new strategy, the transfer element method (TEM), to realize the prescribed noise reduction objective at the preliminary phase of the acoustic design of aeroengine nacelle. Section 6.1 gives an overview of noise prediction in an aeroengine nacelle. Section 6.2 introduces the basic theory of sound propagation in the duct. Section 6.3 sets up the transfer element for the sound propagation in a finite lined duct. Section 6.4 focuses on the transfer element for the sound generation by rotor-stator interaction in a finite duct. Section 6.5 discusses the effect of various interactions between the sound source and acoustic liners.