Aeroacoustics

Challenges and Motivations

Aims of researches conducted in aeroacoustics are to reduce noise generated by turbulent flows. The main pollutions are related to transportation systems in urban environment: noise in the vicinity of roads, railways or airports. To this societal issue, there are also strategic and economic interests to ensure the development of the transportation industry. As illustration of problems regularly encountered in engineering, we can mention noise induced by wall pressure fluctuations, flow noise in sonar domes for underwater applications, aircraft interior noise or the protection of payload of space launchers. Scientific challenges of aeroacoustics are also very numerous, but before developing this point, it is necessary to define the discipline and scientific contours of the present special interest group.

SIG 39 – Frontiers of Aeroacoustics

Aeroacoustics is the discipline devoted to the study of aerodynamic noise, to its propagation in generally non-homogeneous media, its radiation in far field and also ways to reduce noise by active control of sound field or more directly by control of sources of sound. Only the generation and propagation in gases is retained here. Similar phenomena occur in case of heavy fluids, as for acoustic propagation underwater for example, and a distinction is often made between aeroacoustics and hydroacoustics. Problems involving thermo-acoustic instabilities (see SIG 28), wall pressure fluctuations exciting structures (see SIG 41), or modelling of boundary conditions to address problems of propagation or control are also close to current activities in the group. The noise monitoring may also be used as a diagnostic tool for duct propagation, rotating machines or medicine. These frontiers correspond fairly well to what can be observed in international conferences and research programs initiated by Europe.

Research topics:

• physics of aerodynamic noise
• computational aeroacoustics
• active noise control
• jet noise
• airframe/high-lift noise
• turbomachinary noise
• long-range propagation in non-homogeneous media
• sonic boom

Purpose and focus of SIG

A considerable number of research topics related to turbulence and compressible flows are under the scope of the SIG 39, as identification of turbulent mechanisms that generate the acoustic sources or propagation phenomena in complex flows. These problems are nonlinear and multi-scales. Wave nature of sound and its very low energy level compared to the turbulent flow among other features, require specific developments in numerical simulations as well as in experiments. Another particularity of the problems addressed in aeroacoustics is the coupling that often occurs with another discipline as already mentioned above.

Purpose of SIG 39 is mainly to organise events of interest for the group as summer schools, courses and workshops.