'Whistler nozzle' and horn as aero-acoustic sound sources in pipe systems

Abstract

The production of self sustained pulsations in a 'whistler nozzle' is analysed in terms of the periodic shedding of vortices. It is shown that very high acoustic velocities can be obtained by combining the nozzle with an upstream side branch. Acoustic velocities of half the main flow velocity have been observed in a nozzle with rounded edges. In a similar way, in combination with a closed side branch a horn appears to be a powerful sound source.