[en] The production of self-sustained tones (up to 125 dB) by a low Mach number free plane jet
impinging on a slotted plate, known as slot-tone, is experimentally studied. For all geometries
of the slot’s edge tested, the tones are generated from 6 m/s and when a resonant mode of
the duct from which the jet flows out is excited. The Strouhal number associated with the
tones fundamental frequency describes stages. These one are linked to the number of
vortices present, with vortex pairing possibilities. On the other hand, the frequency domain of
the fundamental is defined by the two instability modes of the jet. If the edge of the slot is
beveled and if this one is placed backwards to the flow, the tones occurs at a lower speed
(3.5 m/s) as soon as the jet becomes turbulent, and the excitation of an acoustic resonator is
then not necessary.
