Experiments on the Transmission of Sound Through Jets

E on the superposition of a turbulent jet flow (0<A/<0.7) and pure tone sound coming from inside the nozzle are reported. A comparison between the transmitted sound power from the nozzle and the radiated sound power in the far field reveals a substantial attenuation at low frequencies. Therefore, a jet can be considered as a low-frequency muffler. It has been verified that this effect is independent of the broadband jet noise amplification previously reported by Bechert and Pfizenmaier.