Impact of multipole matching resolution on supersonic aircraft sonic boom assessment

¹ Applied Aerodynamics Department, Civil Aircraft Unit Office National d'Etudes et de Recherches Aérospatiales (ONERA) 8 Rue des Vertugadins, Meudon 92190, France
² Department of Numerical Simulation and Aeroacoustics, ONERA BP 72-29, Av. de la Division Leclerc, Châtillon Cedex 92322, France

Abstract

Sonic boom assessment methods through numerical analysis have been ever-evolving since the development of the fundamental theory. With the growing need for efficient low-boom design tools and the increasing computational resources, original approaches using advanced numerical simulation techniques have been developed. Among the various existing methods, the three-layer resolution introduced in the 1990s is very convenient for low-boom aircraft design. It is based on near-field computational fluid dynamics (CFD) calculation which is matched with the far-field propagation code using a description of the source with multipoles before undergoing classical acoustic propagation through atmosphere. The present paper reviews the theory of the near- to far-field matching as well as the different resolution approaches and their limits. The impact of the resolution method on the ground propagated signal is also presented.