Aeroacoustics of jet and cavity flows

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Many flows in engineering applications, whether it is a nuclear reactor, a jet engine or a simple piping system, are turbulent in nature and therefore produce pressure pulsations. A good design, that is safe, efficient and quiet, opts to maintain these pulsations at an acceptable low level. However, in some cases involving acoustic resonators, such as a simple pipe connected to a valve, the flow turbulence can excite powerful acoustic resonances. An example would be the pleasant tones of the flute, which are produced when the turbulence of the air stream being blown excites the sound waves inside the flute "pipe". When these phenomena occur in industrial applications, the results are less benign than those of the flute. The pressure pulsations can be sufficiently strong to generate dangerous excessive vibrations, deafening noise levels or cause structural failures and thereby endanger the safety and the environment at the work place and neighboring communities.