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Let's assume air flows through a pipe and exits into free atmosphere. The atmospheric pressure is below the critical pressure of the flow, hence the gas is accelerated and a sonic jet forms at the opening.

Superimposed on the air flow within the pipe is a sound wave. The wave experiences a reflection at the open end of the pipe, and the part of the wave transmitted into atmosphere is interacting with the jet.

The question is - to what degree does the sonic jet attenuate the transmitted sound wave?

This problem is rather common in exhaust tail pipe acoustics and covered in the literature (for example Munjal, M.L. (1987); "Acoustics of Ducts and Mufflers", John Wiley & Sons). However, these considerations are limited to moderate mean flow velocities in both the pipe and the jet (M << 1.0). We find that an increasing jet velocity leads to an increasing sound absorption at low frequencies, due to dissipation effects within the shear flow of the jet.

However, I'm looking at a sonic jet. Can anybody point me to literature or resources which discuss in detail the interaction of a sonic jet with a transmitted sound wave?

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